diff --git a/phpunit b/phpunit
index f2718fadcf..437f7b9b44 100755
--- a/phpunit
+++ b/phpunit
@@ -1,7 +1,7 @@
 #!/usr/bin/env php
 <?php
 
-// Cache-Id: https://github.com/symfony/phpunit-bridge/commit/da3d101c8db7e7612069406c4ca6b1986b6f4942
+// Cache-Id: https://github.com/symfony/phpunit-bridge/commit/6ce862d9166ac77f611cc97789e91cb4f51f0021
 
 if (!file_exists(__DIR__.'/vendor/symfony/phpunit-bridge/bin/simple-phpunit')) {
     echo "Unable to find the `simple-phpunit` script in `vendor/symfony/phpunit-bridge/bin/`.\nPlease run `composer update` before running this command.\n";
diff --git a/src/Symfony/Bridge/Monolog/Tests/Handler/ConsoleHandlerTest.php b/src/Symfony/Bridge/Monolog/Tests/Handler/ConsoleHandlerTest.php
index afd07683e4..5a59d29346 100644
--- a/src/Symfony/Bridge/Monolog/Tests/Handler/ConsoleHandlerTest.php
+++ b/src/Symfony/Bridge/Monolog/Tests/Handler/ConsoleHandlerTest.php
@@ -197,12 +197,12 @@ class ConsoleHandlerTest extends TestCase
 
         $event = new ConsoleCommandEvent(new Command('foo'), $this->getMockBuilder('Symfony\Component\Console\Input\InputInterface')->getMock(), $output);
         $dispatcher->dispatch($event, ConsoleEvents::COMMAND);
-        $this->assertContains('Before command message.', $out = $output->fetch());
-        $this->assertContains('After command message.', $out);
+        $this->assertStringContainsString('Before command message.', $out = $output->fetch());
+        $this->assertStringContainsString('After command message.', $out);
 
         $event = new ConsoleTerminateEvent(new Command('foo'), $this->getMockBuilder('Symfony\Component\Console\Input\InputInterface')->getMock(), $output, 0);
         $dispatcher->dispatch($event, ConsoleEvents::TERMINATE);
-        $this->assertContains('Before terminate message.', $out = $output->fetch());
-        $this->assertContains('After terminate message.', $out);
+        $this->assertStringContainsString('Before terminate message.', $out = $output->fetch());
+        $this->assertStringContainsString('After terminate message.', $out);
     }
 }
diff --git a/src/Symfony/Bridge/PhpUnit/Tests/CoverageListenerTest.php b/src/Symfony/Bridge/PhpUnit/Tests/CoverageListenerTest.php
index b7ba8b0d3d..7aae33bbad 100644
--- a/src/Symfony/Bridge/PhpUnit/Tests/CoverageListenerTest.php
+++ b/src/Symfony/Bridge/PhpUnit/Tests/CoverageListenerTest.php
@@ -29,14 +29,14 @@ class CoverageListenerTest extends TestCase
 
         exec("$php $phpunit -c $dir/phpunit-without-listener.xml.dist $dir/tests/ --coverage-text 2> /dev/null", $output);
         $output = implode("\n", $output);
-        $this->assertContains('FooCov', $output);
+        $this->assertStringContainsString('FooCov', $output);
 
         exec("$php $phpunit -c $dir/phpunit-with-listener.xml.dist $dir/tests/ --coverage-text 2> /dev/null", $output);
         $output = implode("\n", $output);
-        $this->assertNotContains('FooCov', $output);
-        $this->assertContains("SutNotFoundTest::test\nCould not find the tested class.", $output);
-        $this->assertNotContains("CoversTest::test\nCould not find the tested class.", $output);
-        $this->assertNotContains("CoversDefaultClassTest::test\nCould not find the tested class.", $output);
-        $this->assertNotContains("CoversNothingTest::test\nCould not find the tested class.", $output);
+        $this->assertStringNotContainsString('FooCov', $output);
+        $this->assertStringContainsString("SutNotFoundTest::test\nCould not find the tested class.", $output);
+        $this->assertStringNotContainsString("CoversTest::test\nCould not find the tested class.", $output);
+        $this->assertStringNotContainsString("CoversDefaultClassTest::test\nCould not find the tested class.", $output);
+        $this->assertStringNotContainsString("CoversNothingTest::test\nCould not find the tested class.", $output);
     }
 }
diff --git a/src/Symfony/Bridge/Twig/Tests/Command/DebugCommandTest.php b/src/Symfony/Bridge/Twig/Tests/Command/DebugCommandTest.php
index 964b29acd9..0a500e1279 100644
--- a/src/Symfony/Bridge/Twig/Tests/Command/DebugCommandTest.php
+++ b/src/Symfony/Bridge/Twig/Tests/Command/DebugCommandTest.php
@@ -27,7 +27,7 @@ class DebugCommandTest extends TestCase
         $ret = $tester->execute([], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('Functions', trim($tester->getDisplay()));
+        $this->assertStringContainsString('Functions', trim($tester->getDisplay()));
     }
 
     public function testFilterAndJsonFormatOptions()
@@ -284,7 +284,7 @@ TXT
         $ret = $tester->execute(['name' => 'base.html.twig'], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('[OK]', $tester->getDisplay());
+        $this->assertStringContainsString('[OK]', $tester->getDisplay());
     }
 
     public function testWithGlobals()
@@ -293,7 +293,7 @@ TXT
         $tester = $this->createCommandTester([], [], null, null, false, ['message' => $message]);
         $tester->execute([], ['decorated' => true]);
         $display = $tester->getDisplay();
-        $this->assertContains(json_encode($message), $display);
+        $this->assertStringContainsString(json_encode($message), $display);
     }
 
     public function testWithGlobalsJson()
diff --git a/src/Symfony/Bridge/Twig/Tests/Command/LintCommandTest.php b/src/Symfony/Bridge/Twig/Tests/Command/LintCommandTest.php
index e1fb436127..df99cd7518 100644
--- a/src/Symfony/Bridge/Twig/Tests/Command/LintCommandTest.php
+++ b/src/Symfony/Bridge/Twig/Tests/Command/LintCommandTest.php
@@ -31,7 +31,7 @@ class LintCommandTest extends TestCase
         $ret = $tester->execute(['filename' => [$filename]], ['verbosity' => OutputInterface::VERBOSITY_VERBOSE, 'decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('OK in', trim($tester->getDisplay()));
+        $this->assertStringContainsString('OK in', trim($tester->getDisplay()));
     }
 
     public function testLintIncorrectFile()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/RouterMatchCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/RouterMatchCommandTest.php
index 497511f629..a4182d2618 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/RouterMatchCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/RouterMatchCommandTest.php
@@ -29,7 +29,7 @@ class RouterMatchCommandTest extends TestCase
         $ret = $tester->execute(['path_info' => '/foo', 'foo'], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('Route Name   | foo', $tester->getDisplay());
+        $this->assertStringContainsString('Route Name   | foo', $tester->getDisplay());
     }
 
     public function testWithNotMatchPath()
@@ -38,7 +38,7 @@ class RouterMatchCommandTest extends TestCase
         $ret = $tester->execute(['path_info' => '/test', 'foo'], ['decorated' => false]);
 
         $this->assertEquals(1, $ret, 'Returns 1 in case of failure');
-        $this->assertContains('None of the routes match the path "/test"', $tester->getDisplay());
+        $this->assertStringContainsString('None of the routes match the path "/test"', $tester->getDisplay());
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/YamlLintCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/YamlLintCommandTest.php
index cb6595bf1f..410ab4f90c 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/YamlLintCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/YamlLintCommandTest.php
@@ -41,7 +41,7 @@ class YamlLintCommandTest extends TestCase
         );
 
         $this->assertEquals(0, $tester->getStatusCode(), 'Returns 0 in case of success');
-        $this->assertContains('OK', trim($tester->getDisplay()));
+        $this->assertStringContainsString('OK', trim($tester->getDisplay()));
     }
 
     public function testLintIncorrectFile()
@@ -55,7 +55,7 @@ bar';
         $tester->execute(['filename' => $filename], ['decorated' => false]);
 
         $this->assertEquals(1, $tester->getStatusCode(), 'Returns 1 in case of error');
-        $this->assertContains('Unable to parse at line 3 (near "bar").', trim($tester->getDisplay()));
+        $this->assertStringContainsString('Unable to parse at line 3 (near "bar").', trim($tester->getDisplay()));
     }
 
     public function testLintFileNotReadable()
@@ -106,7 +106,7 @@ EOF;
         );
 
         $this->assertEquals(0, $tester->getStatusCode(), 'Returns 0 in case of success');
-        $this->assertContains('[OK] All 0 YAML files contain valid syntax', trim($tester->getDisplay()));
+        $this->assertStringContainsString('[OK] All 0 YAML files contain valid syntax', trim($tester->getDisplay()));
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Console/ApplicationTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Console/ApplicationTest.php
index c9f93b96ea..f8fe513d51 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Console/ApplicationTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Console/ApplicationTest.php
@@ -167,9 +167,9 @@ class ApplicationTest extends TestCase
         $output = $tester->getDisplay();
 
         $this->assertSame(0, $tester->getStatusCode());
-        $this->assertContains('Some commands could not be registered:', $output);
-        $this->assertContains('throwing', $output);
-        $this->assertContains('fine', $output);
+        $this->assertStringContainsString('Some commands could not be registered:', $output);
+        $this->assertStringContainsString('throwing', $output);
+        $this->assertStringContainsString('fine', $output);
     }
 
     public function testRegistrationErrorsAreDisplayedOnCommandNotFound()
@@ -195,8 +195,8 @@ class ApplicationTest extends TestCase
         $output = $tester->getDisplay();
 
         $this->assertSame(1, $tester->getStatusCode());
-        $this->assertContains('Some commands could not be registered:', $output);
-        $this->assertContains('Command "fine" is not defined.', $output);
+        $this->assertStringContainsString('Some commands could not be registered:', $output);
+        $this->assertStringContainsString('Command "fine" is not defined.', $output);
     }
 
     public function testRunOnlyWarnsOnUnregistrableCommandAtTheEnd()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerNameParserTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerNameParserTest.php
index 1805fa074b..bdee7c8ecf 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerNameParserTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerNameParserTest.php
@@ -129,9 +129,9 @@ class ControllerNameParserTest extends TestCase
 
             if (false === $suggestedBundleName) {
                 // make sure we don't have a suggestion
-                $this->assertNotContains('Did you mean', $e->getMessage());
+                $this->assertStringNotContainsString('Did you mean', $e->getMessage());
             } else {
-                $this->assertContains(sprintf('Did you mean "%s"', $suggestedBundleName), $e->getMessage());
+                $this->assertStringContainsString(sprintf('Did you mean "%s"', $suggestedBundleName), $e->getMessage());
             }
         }
     }
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerTraitTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerTraitTest.php
index c3a49dd61b..462a415fff 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerTraitTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/ControllerTraitTest.php
@@ -187,8 +187,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
-        $this->assertContains(basename(__FILE__), $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(basename(__FILE__), $response->headers->get('content-disposition'));
     }
 
     public function testFileAsInline()
@@ -203,8 +203,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_INLINE, $response->headers->get('content-disposition'));
-        $this->assertContains(basename(__FILE__), $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_INLINE, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(basename(__FILE__), $response->headers->get('content-disposition'));
     }
 
     public function testFileWithOwnFileName()
@@ -220,8 +220,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
-        $this->assertContains($fileName, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString($fileName, $response->headers->get('content-disposition'));
     }
 
     public function testFileWithOwnFileNameAsInline()
@@ -237,8 +237,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_INLINE, $response->headers->get('content-disposition'));
-        $this->assertContains($fileName, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_INLINE, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString($fileName, $response->headers->get('content-disposition'));
     }
 
     public function testFileFromPath()
@@ -253,8 +253,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
-        $this->assertContains(basename(__FILE__), $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(basename(__FILE__), $response->headers->get('content-disposition'));
     }
 
     public function testFileFromPathWithCustomizedFileName()
@@ -269,8 +269,8 @@ abstract class ControllerTraitTest extends TestCase
         if ($response->headers->get('content-type')) {
             $this->assertSame('text/x-php', $response->headers->get('content-type'));
         }
-        $this->assertContains(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
-        $this->assertContains('test.php', $response->headers->get('content-disposition'));
+        $this->assertStringContainsString(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $response->headers->get('content-disposition'));
+        $this->assertStringContainsString('test.php', $response->headers->get('content-disposition'));
     }
 
     public function testFileWhichDoesNotExist()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
index 8cfa3deff6..76d9d4ccfe 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
@@ -1079,9 +1079,9 @@ abstract class FrameworkExtensionTest extends TestCase
 
         $this->assertSame('addYamlMappings', $calls[4][0]);
         $this->assertCount(3, $calls[4][1][0]);
-        $this->assertContains('foo.yml', $calls[4][1][0][0]);
-        $this->assertContains('validation.yml', $calls[4][1][0][1]);
-        $this->assertContains('validation.yaml', $calls[4][1][0][2]);
+        $this->assertStringContainsString('foo.yml', $calls[4][1][0][0]);
+        $this->assertStringContainsString('validation.yml', $calls[4][1][0][1]);
+        $this->assertStringContainsString('validation.yaml', $calls[4][1][0][2]);
     }
 
     public function testValidationAutoMapping()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/CachePoolClearCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/CachePoolClearCommandTest.php
index 0cd9195d99..a47b78933b 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/CachePoolClearCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/CachePoolClearCommandTest.php
@@ -31,8 +31,8 @@ class CachePoolClearCommandTest extends AbstractWebTestCase
         $tester->execute(['pools' => ['cache.private_pool']], ['decorated' => false]);
 
         $this->assertSame(0, $tester->getStatusCode(), 'cache:pool:clear exits with 0 in case of success');
-        $this->assertContains('Clearing cache pool: cache.private_pool', $tester->getDisplay());
-        $this->assertContains('[OK] Cache was successfully cleared.', $tester->getDisplay());
+        $this->assertStringContainsString('Clearing cache pool: cache.private_pool', $tester->getDisplay());
+        $this->assertStringContainsString('[OK] Cache was successfully cleared.', $tester->getDisplay());
     }
 
     public function testClearPublicPool()
@@ -41,8 +41,8 @@ class CachePoolClearCommandTest extends AbstractWebTestCase
         $tester->execute(['pools' => ['cache.public_pool']], ['decorated' => false]);
 
         $this->assertSame(0, $tester->getStatusCode(), 'cache:pool:clear exits with 0 in case of success');
-        $this->assertContains('Clearing cache pool: cache.public_pool', $tester->getDisplay());
-        $this->assertContains('[OK] Cache was successfully cleared.', $tester->getDisplay());
+        $this->assertStringContainsString('Clearing cache pool: cache.public_pool', $tester->getDisplay());
+        $this->assertStringContainsString('[OK] Cache was successfully cleared.', $tester->getDisplay());
     }
 
     public function testClearPoolWithCustomClearer()
@@ -51,8 +51,8 @@ class CachePoolClearCommandTest extends AbstractWebTestCase
         $tester->execute(['pools' => ['cache.pool_with_clearer']], ['decorated' => false]);
 
         $this->assertSame(0, $tester->getStatusCode(), 'cache:pool:clear exits with 0 in case of success');
-        $this->assertContains('Clearing cache pool: cache.pool_with_clearer', $tester->getDisplay());
-        $this->assertContains('[OK] Cache was successfully cleared.', $tester->getDisplay());
+        $this->assertStringContainsString('Clearing cache pool: cache.pool_with_clearer', $tester->getDisplay());
+        $this->assertStringContainsString('[OK] Cache was successfully cleared.', $tester->getDisplay());
     }
 
     public function testCallClearer()
@@ -61,8 +61,8 @@ class CachePoolClearCommandTest extends AbstractWebTestCase
         $tester->execute(['pools' => ['cache.app_clearer']], ['decorated' => false]);
 
         $this->assertSame(0, $tester->getStatusCode(), 'cache:pool:clear exits with 0 in case of success');
-        $this->assertContains('Calling cache clearer: cache.app_clearer', $tester->getDisplay());
-        $this->assertContains('[OK] Cache was successfully cleared.', $tester->getDisplay());
+        $this->assertStringContainsString('Calling cache clearer: cache.app_clearer', $tester->getDisplay());
+        $this->assertStringContainsString('[OK] Cache was successfully cleared.', $tester->getDisplay());
     }
 
     public function testClearUnexistingPool()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
index 290d9a85c1..d47aa9ba2e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
@@ -36,7 +36,7 @@ class ConfigDebugCommandTest extends AbstractWebTestCase
         $ret = $tester->execute(['name' => 'TestBundle']);
 
         $this->assertSame(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('custom: foo', $tester->getDisplay());
+        $this->assertStringContainsString('custom: foo', $tester->getDisplay());
     }
 
     public function testDumpBundleOption()
@@ -45,7 +45,7 @@ class ConfigDebugCommandTest extends AbstractWebTestCase
         $ret = $tester->execute(['name' => 'TestBundle', 'path' => 'custom']);
 
         $this->assertSame(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('foo', $tester->getDisplay());
+        $this->assertStringContainsString('foo', $tester->getDisplay());
     }
 
     public function testParametersValuesAreResolved()
@@ -54,8 +54,8 @@ class ConfigDebugCommandTest extends AbstractWebTestCase
         $ret = $tester->execute(['name' => 'framework']);
 
         $this->assertSame(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains("locale: '%env(LOCALE)%'", $tester->getDisplay());
-        $this->assertContains('secret: test', $tester->getDisplay());
+        $this->assertStringContainsString("locale: '%env(LOCALE)%'", $tester->getDisplay());
+        $this->assertStringContainsString('secret: test', $tester->getDisplay());
     }
 
     public function testDumpUndefinedBundleOption()
@@ -63,7 +63,7 @@ class ConfigDebugCommandTest extends AbstractWebTestCase
         $tester = $this->createCommandTester();
         $tester->execute(['name' => 'TestBundle', 'path' => 'foo']);
 
-        $this->assertContains('Unable to find configuration for "test.foo"', $tester->getDisplay());
+        $this->assertStringContainsString('Unable to find configuration for "test.foo"', $tester->getDisplay());
     }
 
     public function testDumpWithPrefixedEnv()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDumpReferenceCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDumpReferenceCommandTest.php
index b8ac6645f6..aa5dba65c0 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDumpReferenceCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDumpReferenceCommandTest.php
@@ -36,8 +36,8 @@ class ConfigDumpReferenceCommandTest extends AbstractWebTestCase
         $ret = $tester->execute(['name' => 'TestBundle']);
 
         $this->assertSame(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('test:', $tester->getDisplay());
-        $this->assertContains('    custom:', $tester->getDisplay());
+        $this->assertStringContainsString('test:', $tester->getDisplay());
+        $this->assertStringContainsString('    custom:', $tester->getDisplay());
     }
 
     public function testDumpAtPath()
@@ -70,7 +70,7 @@ EOL
         ]);
 
         $this->assertSame(1, $ret);
-        $this->assertContains('[ERROR] The "path" option is only available for the "yaml" format.', $tester->getDisplay());
+        $this->assertStringContainsString('[ERROR] The "path" option is only available for the "yaml" format.', $tester->getDisplay());
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
index bb8fa9cfd3..b3327ed0ac 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
@@ -45,7 +45,7 @@ class ContainerDebugCommandTest extends AbstractWebTestCase
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'debug:container']);
 
-        $this->assertContains('public', $tester->getDisplay());
+        $this->assertStringContainsString('public', $tester->getDisplay());
     }
 
     public function testPrivateAlias()
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/DebugAutowiringCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/DebugAutowiringCommandTest.php
index af6228022e..b4ffba44e3 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/DebugAutowiringCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/DebugAutowiringCommandTest.php
@@ -29,8 +29,8 @@ class DebugAutowiringCommandTest extends AbstractWebTestCase
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'debug:autowiring']);
 
-        $this->assertContains('Symfony\Component\HttpKernel\HttpKernelInterface', $tester->getDisplay());
-        $this->assertContains('(http_kernel)', $tester->getDisplay());
+        $this->assertStringContainsString('Symfony\Component\HttpKernel\HttpKernelInterface', $tester->getDisplay());
+        $this->assertStringContainsString('(http_kernel)', $tester->getDisplay());
     }
 
     public function testSearchArgument()
@@ -43,8 +43,8 @@ class DebugAutowiringCommandTest extends AbstractWebTestCase
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'debug:autowiring', 'search' => 'kern']);
 
-        $this->assertContains('Symfony\Component\HttpKernel\HttpKernelInterface', $tester->getDisplay());
-        $this->assertNotContains('Symfony\Component\Routing\RouterInterface', $tester->getDisplay());
+        $this->assertStringContainsString('Symfony\Component\HttpKernel\HttpKernelInterface', $tester->getDisplay());
+        $this->assertStringNotContainsString('Symfony\Component\Routing\RouterInterface', $tester->getDisplay());
     }
 
     public function testSearchIgnoreBackslashWhenFindingService()
@@ -69,7 +69,7 @@ class DebugAutowiringCommandTest extends AbstractWebTestCase
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'debug:autowiring', 'search' => 'foo_fake'], ['capture_stderr_separately' => true]);
 
-        $this->assertContains('No autowirable classes or interfaces found matching "foo_fake"', $tester->getErrorOutput());
+        $this->assertStringContainsString('No autowirable classes or interfaces found matching "foo_fake"', $tester->getErrorOutput());
         $this->assertEquals(1, $tester->getStatusCode());
     }
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
index 0fa8a09b4b..c99b5e073e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
@@ -27,23 +27,23 @@ class SessionTest extends AbstractWebTestCase
 
         // no session
         $crawler = $client->request('GET', '/session');
-        $this->assertContains('You are new here and gave no name.', $crawler->text());
+        $this->assertStringContainsString('You are new here and gave no name.', $crawler->text());
 
         // remember name
         $crawler = $client->request('GET', '/session/drak');
-        $this->assertContains('Hello drak, nice to meet you.', $crawler->text());
+        $this->assertStringContainsString('Hello drak, nice to meet you.', $crawler->text());
 
         // prove remembered name
         $crawler = $client->request('GET', '/session');
-        $this->assertContains('Welcome back drak, nice to meet you.', $crawler->text());
+        $this->assertStringContainsString('Welcome back drak, nice to meet you.', $crawler->text());
 
         // clear session
         $crawler = $client->request('GET', '/session_logout');
-        $this->assertContains('Session cleared.', $crawler->text());
+        $this->assertStringContainsString('Session cleared.', $crawler->text());
 
         // prove cleared session
         $crawler = $client->request('GET', '/session');
-        $this->assertContains('You are new here and gave no name.', $crawler->text());
+        $this->assertStringContainsString('You are new here and gave no name.', $crawler->text());
     }
 
     /**
@@ -62,11 +62,11 @@ class SessionTest extends AbstractWebTestCase
         $crawler = $client->request('GET', '/session_setflash/Hello%20world.');
 
         // check flash displays on redirect
-        $this->assertContains('Hello world.', $client->followRedirect()->text());
+        $this->assertStringContainsString('Hello world.', $client->followRedirect()->text());
 
         // check flash is gone
         $crawler = $client->request('GET', '/session_showflash');
-        $this->assertContains('No flash was set.', $crawler->text());
+        $this->assertStringContainsString('No flash was set.', $crawler->text());
     }
 
     /**
@@ -91,39 +91,39 @@ class SessionTest extends AbstractWebTestCase
 
         // new session, so no name set.
         $crawler1 = $client1->request('GET', '/session');
-        $this->assertContains('You are new here and gave no name.', $crawler1->text());
+        $this->assertStringContainsString('You are new here and gave no name.', $crawler1->text());
 
         // set name of client1
         $crawler1 = $client1->request('GET', '/session/client1');
-        $this->assertContains('Hello client1, nice to meet you.', $crawler1->text());
+        $this->assertStringContainsString('Hello client1, nice to meet you.', $crawler1->text());
 
         // no session for client2
         $crawler2 = $client2->request('GET', '/session');
-        $this->assertContains('You are new here and gave no name.', $crawler2->text());
+        $this->assertStringContainsString('You are new here and gave no name.', $crawler2->text());
 
         // remember name client2
         $crawler2 = $client2->request('GET', '/session/client2');
-        $this->assertContains('Hello client2, nice to meet you.', $crawler2->text());
+        $this->assertStringContainsString('Hello client2, nice to meet you.', $crawler2->text());
 
         // prove remembered name of client1
         $crawler1 = $client1->request('GET', '/session');
-        $this->assertContains('Welcome back client1, nice to meet you.', $crawler1->text());
+        $this->assertStringContainsString('Welcome back client1, nice to meet you.', $crawler1->text());
 
         // prove remembered name of client2
         $crawler2 = $client2->request('GET', '/session');
-        $this->assertContains('Welcome back client2, nice to meet you.', $crawler2->text());
+        $this->assertStringContainsString('Welcome back client2, nice to meet you.', $crawler2->text());
 
         // clear client1
         $crawler1 = $client1->request('GET', '/session_logout');
-        $this->assertContains('Session cleared.', $crawler1->text());
+        $this->assertStringContainsString('Session cleared.', $crawler1->text());
 
         // prove client1 data is cleared
         $crawler1 = $client1->request('GET', '/session');
-        $this->assertContains('You are new here and gave no name.', $crawler1->text());
+        $this->assertStringContainsString('You are new here and gave no name.', $crawler1->text());
 
         // prove remembered name of client2 remains untouched.
         $crawler2 = $client2->request('GET', '/session');
-        $this->assertContains('Welcome back client2, nice to meet you.', $crawler2->text());
+        $this->assertStringContainsString('Welcome back client2, nice to meet you.', $crawler2->text());
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Templating/Loader/TemplateLocatorTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Templating/Loader/TemplateLocatorTest.php
index a2b3327905..63581e131e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Templating/Loader/TemplateLocatorTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Templating/Loader/TemplateLocatorTest.php
@@ -72,7 +72,7 @@ class TemplateLocatorTest extends TestCase
             $locator->locate($template);
             $this->fail('->locate() should throw an exception when the file is not found.');
         } catch (\InvalidArgumentException $e) {
-            $this->assertContains(
+            $this->assertStringContainsString(
                 $errorMessage,
                 $e->getMessage(),
                 'TemplateLocator exception should propagate the FileLocator exception message'
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/CsrfFormLoginTest.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/CsrfFormLoginTest.php
index a701c8e4ea..dc2aeaec50 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/CsrfFormLoginTest.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/CsrfFormLoginTest.php
@@ -30,12 +30,12 @@ class CsrfFormLoginTest extends AbstractWebTestCase
         $crawler = $client->followRedirect();
 
         $text = $crawler->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/profile".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/profile".', $text);
 
         $logoutLinks = $crawler->selectLink('Log out')->links();
         $this->assertCount(2, $logoutLinks);
-        $this->assertContains('_csrf_token=', $logoutLinks[0]->getUri());
+        $this->assertStringContainsString('_csrf_token=', $logoutLinks[0]->getUri());
         $this->assertSame($logoutLinks[0]->getUri(), $logoutLinks[1]->getUri());
 
         $client->click($logoutLinks[0]);
@@ -57,7 +57,7 @@ class CsrfFormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/login');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Invalid CSRF token.', $text);
+        $this->assertStringContainsString('Invalid CSRF token.', $text);
     }
 
     /**
@@ -76,8 +76,8 @@ class CsrfFormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/foo');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/foo".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/foo".', $text);
     }
 
     /**
@@ -97,8 +97,8 @@ class CsrfFormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/protected-resource');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/protected-resource".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/protected-resource".', $text);
     }
 
     public function getConfigs()
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/FormLoginTest.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/FormLoginTest.php
index af932a3ce4..1959d05576 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/FormLoginTest.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/FormLoginTest.php
@@ -28,8 +28,8 @@ class FormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/profile');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/profile".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/profile".', $text);
     }
 
     /**
@@ -49,8 +49,8 @@ class FormLoginTest extends AbstractWebTestCase
         $crawler = $client->followRedirect();
         $text = $crawler->text();
 
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/profile".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/profile".', $text);
 
         $logoutLinks = $crawler->selectLink('Log out')->links();
         $this->assertCount(6, $logoutLinks);
@@ -81,8 +81,8 @@ class FormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/foo');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/foo".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/foo".', $text);
     }
 
     /**
@@ -102,8 +102,8 @@ class FormLoginTest extends AbstractWebTestCase
         $this->assertRedirect($client->getResponse(), '/protected_resource');
 
         $text = $client->followRedirect()->text();
-        $this->assertContains('Hello johannes!', $text);
-        $this->assertContains('You\'re browsing to path "/protected_resource".', $text);
+        $this->assertStringContainsString('Hello johannes!', $text);
+        $this->assertStringContainsString('You\'re browsing to path "/protected_resource".', $text);
     }
 
     public function getConfigs()
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/UserPasswordEncoderCommandTest.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/UserPasswordEncoderCommandTest.php
index 1860f95726..03da552254 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/UserPasswordEncoderCommandTest.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/UserPasswordEncoderCommandTest.php
@@ -51,7 +51,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             'command' => 'security:encode-password',
         ], ['interactive' => false]);
 
-        $this->assertContains('[ERROR] The password must not be empty.', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString('[ERROR] The password must not be empty.', $this->passwordEncoderCommandTester->getDisplay());
         $this->assertEquals($statusCode, 1);
     }
 
@@ -68,7 +68,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
         ], ['interactive' => false]);
 
         $output = $this->passwordEncoderCommandTester->getDisplay();
-        $this->assertContains('Password encoding succeeded', $output);
+        $this->assertStringContainsString('Password encoding succeeded', $output);
 
         $encoder = new BCryptPasswordEncoder(17);
         preg_match('# Encoded password\s{1,}([\w+\/$.]+={0,2})\s+#', $output, $matches);
@@ -92,7 +92,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
         ], ['interactive' => false]);
 
         $output = $this->passwordEncoderCommandTester->getDisplay();
-        $this->assertContains('Password encoding succeeded', $output);
+        $this->assertStringContainsString('Password encoding succeeded', $output);
 
         $encoder = new Argon2iPasswordEncoder();
         preg_match('#  Encoded password\s+(\$argon2id?\$[\w,=\$+\/]+={0,2})\s+#', $output, $matches);
@@ -146,7 +146,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
         ], ['interactive' => false]);
 
         $output = $this->passwordEncoderCommandTester->getDisplay();
-        $this->assertContains('Password encoding succeeded', $output);
+        $this->assertStringContainsString('Password encoding succeeded', $output);
 
         $encoder = new Pbkdf2PasswordEncoder('sha512', true, 1000);
         preg_match('# Encoded password\s{1,}([\w+\/]+={0,2})\s+#', $output, $matches);
@@ -165,9 +165,9 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             ], ['interactive' => false]
         );
 
-        $this->assertContains('Password encoding succeeded', $this->passwordEncoderCommandTester->getDisplay());
-        $this->assertContains(' Encoded password   p@ssw0rd', $this->passwordEncoderCommandTester->getDisplay());
-        $this->assertContains(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString('Password encoding succeeded', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString(' Encoded password   p@ssw0rd', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
     }
 
     public function testEncodePasswordEmptySaltOutput()
@@ -179,9 +179,9 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             '--empty-salt' => true,
         ]);
 
-        $this->assertContains('Password encoding succeeded', $this->passwordEncoderCommandTester->getDisplay());
-        $this->assertContains(' Encoded password   p@ssw0rd', $this->passwordEncoderCommandTester->getDisplay());
-        $this->assertNotContains(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString('Password encoding succeeded', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString(' Encoded password   p@ssw0rd', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringNotContainsString(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
     }
 
     public function testEncodePasswordNativeOutput()
@@ -192,7 +192,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             'user-class' => 'Custom\Class\Native\User',
         ], ['interactive' => false]);
 
-        $this->assertNotContains(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringNotContainsString(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
     }
 
     /**
@@ -211,7 +211,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             'user-class' => 'Custom\Class\Argon2i\User',
         ], ['interactive' => false]);
 
-        $this->assertNotContains(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringNotContainsString(' Generated salt ', $this->passwordEncoderCommandTester->getDisplay());
     }
 
     public function testEncodePasswordSodiumOutput()
@@ -250,7 +250,7 @@ class UserPasswordEncoderCommandTest extends AbstractWebTestCase
             'password' => 'password',
         ], ['decorated' => false]);
 
-        $this->assertContains(<<<EOTXT
+        $this->assertStringContainsString(<<<EOTXT
  For which user class would you like to encode a password? [Custom\Class\Native\User]:
   [0] Custom\Class\Native\User
   [1] Custom\Class\Pbkdf2\User
@@ -267,7 +267,7 @@ EOTXT
             'password' => 'password',
         ], ['interactive' => false]);
 
-        $this->assertContains('Encoder used       Symfony\Component\Security\Core\Encoder\PlaintextPasswordEncoder', $this->passwordEncoderCommandTester->getDisplay());
+        $this->assertStringContainsString('Encoder used       Symfony\Component\Security\Core\Encoder\PlaintextPasswordEncoder', $this->passwordEncoderCommandTester->getDisplay());
     }
 
     public function testThrowsExceptionOnNoConfiguredEncoders()
diff --git a/src/Symfony/Bundle/TwigBundle/Tests/Functional/NoTemplatingEntryTest.php b/src/Symfony/Bundle/TwigBundle/Tests/Functional/NoTemplatingEntryTest.php
index f1e7709072..e3451ccc31 100644
--- a/src/Symfony/Bundle/TwigBundle/Tests/Functional/NoTemplatingEntryTest.php
+++ b/src/Symfony/Bundle/TwigBundle/Tests/Functional/NoTemplatingEntryTest.php
@@ -27,7 +27,7 @@ class NoTemplatingEntryTest extends TestCase
 
         $container = $kernel->getContainer();
         $content = $container->get('twig')->render('index.html.twig');
-        $this->assertContains('{ a: b }', $content);
+        $this->assertStringContainsString('{ a: b }', $content);
     }
 
     protected function setUp()
diff --git a/src/Symfony/Component/Config/Tests/Fixtures/Resource/.hiddenFile b/src/Symfony/Component/Config/Tests/Fixtures/Resource/.hiddenFile
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/src/Symfony/Component/Config/Tests/Util/XmlUtilsTest.php b/src/Symfony/Component/Config/Tests/Util/XmlUtilsTest.php
index 0c9cbc35f6..4653c8d7c7 100644
--- a/src/Symfony/Component/Config/Tests/Util/XmlUtilsTest.php
+++ b/src/Symfony/Component/Config/Tests/Util/XmlUtilsTest.php
@@ -24,28 +24,28 @@ class XmlUtilsTest extends TestCase
             XmlUtils::loadFile($fixtures.'invalid.xml');
             $this->fail();
         } catch (\InvalidArgumentException $e) {
-            $this->assertContains('ERROR 77', $e->getMessage());
+            $this->assertStringContainsString('ERROR 77', $e->getMessage());
         }
 
         try {
             XmlUtils::loadFile($fixtures.'document_type.xml');
             $this->fail();
         } catch (\InvalidArgumentException $e) {
-            $this->assertContains('Document types are not allowed', $e->getMessage());
+            $this->assertStringContainsString('Document types are not allowed', $e->getMessage());
         }
 
         try {
             XmlUtils::loadFile($fixtures.'invalid_schema.xml', $fixtures.'schema.xsd');
             $this->fail();
         } catch (\InvalidArgumentException $e) {
-            $this->assertContains('ERROR 1845', $e->getMessage());
+            $this->assertStringContainsString('ERROR 1845', $e->getMessage());
         }
 
         try {
             XmlUtils::loadFile($fixtures.'invalid_schema.xml', 'invalid_callback_or_file');
             $this->fail();
         } catch (\InvalidArgumentException $e) {
-            $this->assertContains('XSD file or callable', $e->getMessage());
+            $this->assertStringContainsString('XSD file or callable', $e->getMessage());
         }
 
         $mock = $this->getMockBuilder(__NAMESPACE__.'\Validator')->getMock();
diff --git a/src/Symfony/Component/Console/Tests/ApplicationTest.php b/src/Symfony/Component/Console/Tests/ApplicationTest.php
index e884369b59..c32578d8a6 100644
--- a/src/Symfony/Component/Console/Tests/ApplicationTest.php
+++ b/src/Symfony/Component/Console/Tests/ApplicationTest.php
@@ -184,7 +184,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['test']);
-        $this->assertContains('It works!', $tester->getDisplay(true));
+        $this->assertStringContainsString('It works!', $tester->getDisplay(true));
     }
 
     public function testAdd()
@@ -753,7 +753,7 @@ class ApplicationTest extends TestCase
         $this->assertStringEqualsFile(self::$fixturesPath.'/application_renderexception1.txt', $tester->getErrorOutput(true), '->renderException() renders a pretty exception');
 
         $tester->run(['command' => 'foo'], ['decorated' => false, 'verbosity' => Output::VERBOSITY_VERBOSE, 'capture_stderr_separately' => true]);
-        $this->assertContains('Exception trace', $tester->getErrorOutput(), '->renderException() renders a pretty exception with a stack trace when verbosity is verbose');
+        $this->assertStringContainsString('Exception trace', $tester->getErrorOutput(), '->renderException() renders a pretty exception with a stack trace when verbosity is verbose');
 
         $tester->run(['command' => 'list', '--foo' => true], ['decorated' => false, 'capture_stderr_separately' => true]);
         $this->assertStringEqualsFile(self::$fixturesPath.'/application_renderexception2.txt', $tester->getErrorOutput(true), '->renderException() renders the command synopsis when an exception occurs in the context of a command');
@@ -890,7 +890,7 @@ class ApplicationTest extends TestCase
         $tester = new ApplicationTester($application);
 
         $tester->run(['command' => 'foo'], ['decorated' => false]);
-        $this->assertContains('Dummy type "@anonymous" is invalid.', $tester->getDisplay(true));
+        $this->assertStringContainsString('Dummy type "@anonymous" is invalid.', $tester->getDisplay(true));
     }
 
     public function testRun()
@@ -1315,7 +1315,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'foo']);
-        $this->assertContains('before.foo.error.after.', $tester->getDisplay());
+        $this->assertStringContainsString('before.foo.error.after.', $tester->getDisplay());
     }
 
     public function testRunDispatchesAllEventsWithExceptionInListener()
@@ -1335,7 +1335,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'foo']);
-        $this->assertContains('before.error.after.', $tester->getDisplay());
+        $this->assertStringContainsString('before.error.after.', $tester->getDisplay());
     }
 
     public function testRunWithError()
@@ -1383,7 +1383,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'foo']);
-        $this->assertContains('before.error.silenced.after.', $tester->getDisplay());
+        $this->assertStringContainsString('before.error.silenced.after.', $tester->getDisplay());
         $this->assertEquals(ConsoleCommandEvent::RETURN_CODE_DISABLED, $tester->getStatusCode());
     }
 
@@ -1402,7 +1402,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'unknown']);
-        $this->assertContains('silenced command not found', $tester->getDisplay());
+        $this->assertStringContainsString('silenced command not found', $tester->getDisplay());
         $this->assertEquals(1, $tester->getStatusCode());
     }
 
@@ -1444,7 +1444,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'dym']);
-        $this->assertContains('before.dym.error.after.', $tester->getDisplay(), 'The PHP Error did not dispached events');
+        $this->assertStringContainsString('before.dym.error.after.', $tester->getDisplay(), 'The PHP Error did not dispached events');
     }
 
     public function testRunDispatchesAllEventsWithError()
@@ -1461,7 +1461,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $tester->run(['command' => 'dym']);
-        $this->assertContains('before.dym.error.after.', $tester->getDisplay(), 'The PHP Error did not dispached events');
+        $this->assertStringContainsString('before.dym.error.after.', $tester->getDisplay(), 'The PHP Error did not dispached events');
     }
 
     public function testRunWithErrorFailingStatusCode()
@@ -1493,7 +1493,7 @@ class ApplicationTest extends TestCase
 
         $tester = new ApplicationTester($application);
         $exitCode = $tester->run(['command' => 'foo']);
-        $this->assertContains('before.after.', $tester->getDisplay());
+        $this->assertStringContainsString('before.after.', $tester->getDisplay());
         $this->assertEquals(ConsoleCommandEvent::RETURN_CODE_DISABLED, $exitCode);
     }
 
@@ -1603,10 +1603,10 @@ class ApplicationTest extends TestCase
         $tester = new ApplicationTester($application);
 
         $tester->run([]);
-        $this->assertContains('called', $tester->getDisplay());
+        $this->assertStringContainsString('called', $tester->getDisplay());
 
         $tester->run(['--help' => true]);
-        $this->assertContains('The foo:bar command', $tester->getDisplay());
+        $this->assertStringContainsString('The foo:bar command', $tester->getDisplay());
     }
 
     /**
diff --git a/src/Symfony/Component/Console/Tests/Command/CommandTest.php b/src/Symfony/Component/Console/Tests/Command/CommandTest.php
index 6eff68d94a..9ca4912f88 100644
--- a/src/Symfony/Component/Console/Tests/Command/CommandTest.php
+++ b/src/Symfony/Component/Console/Tests/Command/CommandTest.php
@@ -154,20 +154,20 @@ class CommandTest extends TestCase
     {
         $command = new \TestCommand();
         $command->setHelp('The %command.name% command does... Example: php %command.full_name%.');
-        $this->assertContains('The namespace:name command does...', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.name% correctly');
-        $this->assertNotContains('%command.full_name%', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.full_name%');
+        $this->assertStringContainsString('The namespace:name command does...', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.name% correctly');
+        $this->assertStringNotContainsString('%command.full_name%', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.full_name%');
 
         $command = new \TestCommand();
         $command->setHelp('');
-        $this->assertContains('description', $command->getProcessedHelp(), '->getProcessedHelp() falls back to the description');
+        $this->assertStringContainsString('description', $command->getProcessedHelp(), '->getProcessedHelp() falls back to the description');
 
         $command = new \TestCommand();
         $command->setHelp('The %command.name% command does... Example: php %command.full_name%.');
         $application = new Application();
         $application->add($command);
         $application->setDefaultCommand('namespace:name', true);
-        $this->assertContains('The namespace:name command does...', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.name% correctly in single command applications');
-        $this->assertNotContains('%command.full_name%', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.full_name% in single command applications');
+        $this->assertStringContainsString('The namespace:name command does...', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.name% correctly in single command applications');
+        $this->assertStringNotContainsString('%command.full_name%', $command->getProcessedHelp(), '->getProcessedHelp() replaces %command.full_name% in single command applications');
     }
 
     public function testGetSetAliases()
diff --git a/src/Symfony/Component/Console/Tests/Command/HelpCommandTest.php b/src/Symfony/Component/Console/Tests/Command/HelpCommandTest.php
index ce9d8d4fe4..5b25550a6d 100644
--- a/src/Symfony/Component/Console/Tests/Command/HelpCommandTest.php
+++ b/src/Symfony/Component/Console/Tests/Command/HelpCommandTest.php
@@ -25,9 +25,9 @@ class HelpCommandTest extends TestCase
         $command->setApplication(new Application());
         $commandTester = new CommandTester($command);
         $commandTester->execute(['command_name' => 'li'], ['decorated' => false]);
-        $this->assertContains('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
-        $this->assertContains('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
-        $this->assertContains('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
+        $this->assertStringContainsString('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
+        $this->assertStringContainsString('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
+        $this->assertStringContainsString('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command alias');
     }
 
     public function testExecuteForCommand()
@@ -36,9 +36,9 @@ class HelpCommandTest extends TestCase
         $commandTester = new CommandTester($command);
         $command->setCommand(new ListCommand());
         $commandTester->execute([], ['decorated' => false]);
-        $this->assertContains('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
-        $this->assertContains('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
-        $this->assertContains('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
     }
 
     public function testExecuteForCommandWithXmlOption()
@@ -47,7 +47,7 @@ class HelpCommandTest extends TestCase
         $commandTester = new CommandTester($command);
         $command->setCommand(new ListCommand());
         $commandTester->execute(['--format' => 'xml']);
-        $this->assertContains('<command', $commandTester->getDisplay(), '->execute() returns an XML help text if --xml is passed');
+        $this->assertStringContainsString('<command', $commandTester->getDisplay(), '->execute() returns an XML help text if --xml is passed');
     }
 
     public function testExecuteForApplicationCommand()
@@ -55,9 +55,9 @@ class HelpCommandTest extends TestCase
         $application = new Application();
         $commandTester = new CommandTester($application->get('help'));
         $commandTester->execute(['command_name' => 'list']);
-        $this->assertContains('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
-        $this->assertContains('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
-        $this->assertContains('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('list [options] [--] [<namespace>]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('format=FORMAT', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('raw', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
     }
 
     public function testExecuteForApplicationCommandWithXmlOption()
@@ -65,7 +65,7 @@ class HelpCommandTest extends TestCase
         $application = new Application();
         $commandTester = new CommandTester($application->get('help'));
         $commandTester->execute(['command_name' => 'list', '--format' => 'xml']);
-        $this->assertContains('list [--raw] [--format FORMAT] [--] [&lt;namespace&gt;]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
-        $this->assertContains('<command', $commandTester->getDisplay(), '->execute() returns an XML help text if --format=xml is passed');
+        $this->assertStringContainsString('list [--raw] [--format FORMAT] [--] [&lt;namespace&gt;]', $commandTester->getDisplay(), '->execute() returns a text help for the given command');
+        $this->assertStringContainsString('<command', $commandTester->getDisplay(), '->execute() returns an XML help text if --format=xml is passed');
     }
 }
diff --git a/src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php b/src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php
index d4559e8def..2bcbe51940 100644
--- a/src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php
+++ b/src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php
@@ -86,7 +86,7 @@ class OutputFormatterStyleTest extends TestCase
             $this->fail('->setOption() throws an \InvalidArgumentException when the option does not exist in the available options');
         } catch (\Exception $e) {
             $this->assertInstanceOf('\InvalidArgumentException', $e, '->setOption() throws an \InvalidArgumentException when the option does not exist in the available options');
-            $this->assertContains('Invalid option specified: "foo"', $e->getMessage(), '->setOption() throws an \InvalidArgumentException when the option does not exist in the available options');
+            $this->assertStringContainsString('Invalid option specified: "foo"', $e->getMessage(), '->setOption() throws an \InvalidArgumentException when the option does not exist in the available options');
         }
 
         try {
@@ -94,7 +94,7 @@ class OutputFormatterStyleTest extends TestCase
             $this->fail('->unsetOption() throws an \InvalidArgumentException when the option does not exist in the available options');
         } catch (\Exception $e) {
             $this->assertInstanceOf('\InvalidArgumentException', $e, '->unsetOption() throws an \InvalidArgumentException when the option does not exist in the available options');
-            $this->assertContains('Invalid option specified: "foo"', $e->getMessage(), '->unsetOption() throws an \InvalidArgumentException when the option does not exist in the available options');
+            $this->assertStringContainsString('Invalid option specified: "foo"', $e->getMessage(), '->unsetOption() throws an \InvalidArgumentException when the option does not exist in the available options');
         }
     }
 
diff --git a/src/Symfony/Component/Console/Tests/Helper/HelperSetTest.php b/src/Symfony/Component/Console/Tests/Helper/HelperSetTest.php
index ffb12b3421..d608f7bfd2 100644
--- a/src/Symfony/Component/Console/Tests/Helper/HelperSetTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/HelperSetTest.php
@@ -68,7 +68,7 @@ class HelperSetTest extends TestCase
         } catch (\Exception $e) {
             $this->assertInstanceOf('\InvalidArgumentException', $e, '->get() throws InvalidArgumentException when helper not found');
             $this->assertInstanceOf('Symfony\Component\Console\Exception\ExceptionInterface', $e, '->get() throws domain specific exception when helper not found');
-            $this->assertContains('The helper "foo" is not defined.', $e->getMessage(), '->get() throws InvalidArgumentException when helper not found');
+            $this->assertStringContainsString('The helper "foo" is not defined.', $e->getMessage(), '->get() throws InvalidArgumentException when helper not found');
         }
     }
 
diff --git a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
index c073f30458..e6b0e2a68b 100644
--- a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
@@ -53,7 +53,7 @@ class QuestionHelperTest extends AbstractQuestionHelperTest
 
         rewind($output->getStream());
         $stream = stream_get_contents($output->getStream());
-        $this->assertContains('Input "Fabien" is not a superhero!', $stream);
+        $this->assertStringContainsString('Input "Fabien" is not a superhero!', $stream);
 
         try {
             $question = new ChoiceQuestion('What is your favorite superhero?', $heroes, '1');
diff --git a/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
index a2d78621dd..cbf3b957b3 100644
--- a/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
@@ -161,6 +161,6 @@ class SymfonyQuestionHelperTest extends AbstractQuestionHelperTest
     {
         rewind($output->getStream());
         $stream = stream_get_contents($output->getStream());
-        $this->assertContains($expected, $stream);
+        $this->assertStringContainsString($expected, $stream);
     }
 }
diff --git a/src/Symfony/Component/Debug/Tests/Exception/FlattenExceptionTest.php b/src/Symfony/Component/Debug/Tests/Exception/FlattenExceptionTest.php
index 9317602038..994a5efca1 100644
--- a/src/Symfony/Component/Debug/Tests/Exception/FlattenExceptionTest.php
+++ b/src/Symfony/Component/Debug/Tests/Exception/FlattenExceptionTest.php
@@ -305,7 +305,7 @@ class FlattenExceptionTest extends TestCase
 
         $flattened = FlattenException::create($exception);
         $trace = $flattened->getTrace();
-        $this->assertContains('*DEEP NESTED ARRAY*', serialize($trace));
+        $this->assertStringContainsString('*DEEP NESTED ARRAY*', serialize($trace));
     }
 
     public function testTooBigArray()
@@ -329,8 +329,8 @@ class FlattenExceptionTest extends TestCase
 
         $serializeTrace = serialize($trace);
 
-        $this->assertContains('*SKIPPED over 10000 entries*', $serializeTrace);
-        $this->assertNotContains('*value1*', $serializeTrace);
+        $this->assertStringContainsString('*SKIPPED over 10000 entries*', $serializeTrace);
+        $this->assertStringNotContainsString('*value1*', $serializeTrace);
     }
 
     public function testAnonymousClass()
diff --git a/src/Symfony/Component/Debug/Tests/ExceptionHandlerTest.php b/src/Symfony/Component/Debug/Tests/ExceptionHandlerTest.php
index 3a9af8b6b8..dae390b8cb 100644
--- a/src/Symfony/Component/Debug/Tests/ExceptionHandlerTest.php
+++ b/src/Symfony/Component/Debug/Tests/ExceptionHandlerTest.php
@@ -39,8 +39,8 @@ class ExceptionHandlerTest extends TestCase
         $handler->sendPhpResponse(new \RuntimeException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('Whoops, looks like something went wrong.', $response);
-        $this->assertNotContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('Whoops, looks like something went wrong.', $response);
+        $this->assertStringNotContainsString('<div class="trace trace-as-html">', $response);
 
         $handler = new ExceptionHandler(true);
 
@@ -48,8 +48,8 @@ class ExceptionHandlerTest extends TestCase
         $handler->sendPhpResponse(new \RuntimeException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('<h1 class="break-long-words exception-message">Foo</h1>', $response);
-        $this->assertContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('<h1 class="break-long-words exception-message">Foo</h1>', $response);
+        $this->assertStringContainsString('<div class="trace trace-as-html">', $response);
 
         // taken from https://www.owasp.org/index.php/Cross-site_Scripting_(XSS)
         $htmlWithXss = '<body onload=alert(\'test1\')> <b onmouseover=alert(\'Wufff!\')>click me!</b> <img src="j&#X41vascript:alert(\'test2\')"> <meta http-equiv="refresh"
@@ -69,7 +69,7 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"
         $handler->sendPhpResponse(new NotFoundHttpException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('Sorry, the page you are looking for could not be found.', $response);
+        $this->assertStringContainsString('Sorry, the page you are looking for could not be found.', $response);
 
         $expectedHeaders = [
             ['HTTP/1.0 404', true, null],
@@ -166,7 +166,7 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"
 
     private function assertThatTheExceptionWasOutput($content, $expectedClass, $expectedTitle, $expectedMessage)
     {
-        $this->assertContains(sprintf('<span class="exception_title"><abbr title="%s">%s</abbr></span>', $expectedClass, $expectedTitle), $content);
-        $this->assertContains(sprintf('<p class="break-long-words trace-message">%s</p>', $expectedMessage), $content);
+        $this->assertStringContainsString(sprintf('<span class="exception_title"><abbr title="%s">%s</abbr></span>', $expectedClass, $expectedTitle), $content);
+        $this->assertStringContainsString(sprintf('<p class="break-long-words trace-message">%s</p>', $expectedMessage), $content);
     }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
index 8927dbcf45..c98275144e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
@@ -85,7 +85,7 @@ class MergeExtensionConfigurationPassTest extends TestCase
         $pass = new MergeExtensionConfigurationPass();
         $pass->process($container);
 
-        $this->assertContains(new FileResource(__FILE__), $container->getResources(), '', false, false);
+        $this->assertContainsEquals(new FileResource(__FILE__), $container->getResources());
     }
 
     public function testOverriddenEnvsAreMerged()
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
index df9fcb7b57..0718c8ebef 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
@@ -462,7 +462,7 @@ class XmlFileLoaderTest extends TestCase
 
             $e = $e->getPrevious();
             $this->assertInstanceOf('InvalidArgumentException', $e, '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
-            $this->assertContains('The attribute \'bar\' is not allowed', $e->getMessage(), '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
+            $this->assertStringContainsString('The attribute \'bar\' is not allowed', $e->getMessage(), '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
         }
 
         // non-registered extension
@@ -499,7 +499,7 @@ class XmlFileLoaderTest extends TestCase
 
             $e = $e->getPrevious();
             $this->assertInstanceOf('InvalidArgumentException', $e, '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
-            $this->assertContains('The attribute \'bar\' is not allowed', $e->getMessage(), '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
+            $this->assertStringContainsString('The attribute \'bar\' is not allowed', $e->getMessage(), '->load() throws an InvalidArgumentException if the configuration does not validate the XSD');
         }
     }
 
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
index ccaa00b87c..25fd61cca2 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
@@ -41,7 +41,7 @@ class EnvPlaceholderParameterBagTest extends TestCase
 
         $this->assertCount(1, $placeholderForVariable);
         $this->assertIsString($placeholder);
-        $this->assertContains($envVariableName, $placeholder);
+        $this->assertStringContainsString($envVariableName, $placeholder);
     }
 
     public function testMergeWhereFirstBagIsEmptyWillWork()
@@ -64,7 +64,7 @@ class EnvPlaceholderParameterBagTest extends TestCase
 
         $this->assertCount(1, $placeholderForVariable);
         $this->assertIsString($placeholder);
-        $this->assertContains($envVariableName, $placeholder);
+        $this->assertStringContainsString($envVariableName, $placeholder);
     }
 
     public function testMergeWherePlaceholderOnlyExistsInSecond()
diff --git a/src/Symfony/Component/Form/Tests/AbstractDivLayoutTest.php b/src/Symfony/Component/Form/Tests/AbstractDivLayoutTest.php
index fe0d3e6629..6eef4179e8 100644
--- a/src/Symfony/Component/Form/Tests/AbstractDivLayoutTest.php
+++ b/src/Symfony/Component/Form/Tests/AbstractDivLayoutTest.php
@@ -917,7 +917,7 @@ abstract class AbstractDivLayoutTest extends AbstractLayoutTest
         $html = $this->renderWidget($form->createView());
 
         // compare plain HTML to check the whitespace
-        $this->assertContains('<div id="form" class="foobar" data-foo="bar">', $html);
+        $this->assertStringContainsString('<div id="form" class="foobar" data-foo="bar">', $html);
     }
 
     public function testWidgetContainerAttributeNameRepeatedIfTrue()
@@ -929,6 +929,6 @@ abstract class AbstractDivLayoutTest extends AbstractLayoutTest
         $html = $this->renderWidget($form->createView());
 
         // foo="foo"
-        $this->assertContains('<div id="form" foo="foo">', $html);
+        $this->assertStringContainsString('<div id="form" foo="foo">', $html);
     }
 }
diff --git a/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php b/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
index b03ac0f9fc..8db5fde83f 100644
--- a/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
+++ b/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
@@ -2507,7 +2507,7 @@ abstract class AbstractLayoutTest extends FormIntegrationTestCase
 
         $html = $this->renderWidget($form->createView());
 
-        $this->assertNotContains('foo="', $html);
+        $this->assertStringNotContainsString('foo="', $html);
     }
 
     public function testButtonAttributes()
@@ -2543,7 +2543,7 @@ abstract class AbstractLayoutTest extends FormIntegrationTestCase
 
         $html = $this->renderWidget($form->createView());
 
-        $this->assertNotContains('foo="', $html);
+        $this->assertStringNotContainsString('foo="', $html);
     }
 
     public function testTextareaWithWhitespaceOnlyContentRetainsValue()
@@ -2552,7 +2552,7 @@ abstract class AbstractLayoutTest extends FormIntegrationTestCase
 
         $html = $this->renderWidget($form->createView());
 
-        $this->assertContains('>  </textarea>', $html);
+        $this->assertStringContainsString('>  </textarea>', $html);
     }
 
     public function testTextareaWithWhitespaceOnlyContentRetainsValueWhenRenderingForm()
@@ -2563,7 +2563,7 @@ abstract class AbstractLayoutTest extends FormIntegrationTestCase
 
         $html = $this->renderForm($form->createView());
 
-        $this->assertContains('>  </textarea>', $html);
+        $this->assertStringContainsString('>  </textarea>', $html);
     }
 
     public function testWidgetContainerAttributeHiddenIfFalse()
@@ -2575,7 +2575,7 @@ abstract class AbstractLayoutTest extends FormIntegrationTestCase
         $html = $this->renderWidget($form->createView());
 
         // no foo
-        $this->assertNotContains('foo="', $html);
+        $this->assertStringNotContainsString('foo="', $html);
     }
 
     public function testTranslatedAttributes()
diff --git a/src/Symfony/Component/Form/Tests/AbstractTableLayoutTest.php b/src/Symfony/Component/Form/Tests/AbstractTableLayoutTest.php
index 7cc68bd83d..6240ad2316 100644
--- a/src/Symfony/Component/Form/Tests/AbstractTableLayoutTest.php
+++ b/src/Symfony/Component/Form/Tests/AbstractTableLayoutTest.php
@@ -519,7 +519,7 @@ abstract class AbstractTableLayoutTest extends AbstractLayoutTest
         $html = $this->renderWidget($form->createView());
 
         // compare plain HTML to check the whitespace
-        $this->assertContains('<table id="form" class="foobar" data-foo="bar">', $html);
+        $this->assertStringContainsString('<table id="form" class="foobar" data-foo="bar">', $html);
     }
 
     public function testWidgetContainerAttributeNameRepeatedIfTrue()
@@ -531,6 +531,6 @@ abstract class AbstractTableLayoutTest extends AbstractLayoutTest
         $html = $this->renderWidget($form->createView());
 
         // foo="foo"
-        $this->assertContains('<table id="form" foo="foo">', $html);
+        $this->assertStringContainsString('<table id="form" foo="foo">', $html);
     }
 }
diff --git a/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php b/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
index 8f2669c34b..20a9452369 100644
--- a/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
+++ b/src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php
@@ -31,7 +31,7 @@ class DebugCommandTest extends TestCase
         $ret = $tester->execute([], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('Built-in form types', $tester->getDisplay());
+        $this->assertStringContainsString('Built-in form types', $tester->getDisplay());
     }
 
     public function testDebugDeprecatedDefaults()
@@ -63,7 +63,7 @@ TXT
         $ret = $tester->execute(['class' => 'FormType'], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('Symfony\Component\Form\Extension\Core\Type\FormType (Block prefix: "form")', $tester->getDisplay());
+        $this->assertStringContainsString('Symfony\Component\Form\Extension\Core\Type\FormType (Block prefix: "form")', $tester->getDisplay());
     }
 
     public function testDebugDateTimeType()
@@ -81,7 +81,7 @@ TXT
         $ret = $tester->execute(['class' => 'FormType', 'option' => 'method'], ['decorated' => false]);
 
         $this->assertEquals(0, $ret, 'Returns 0 in case of success');
-        $this->assertContains('Symfony\Component\Form\Extension\Core\Type\FormType (method)', $tester->getDisplay());
+        $this->assertStringContainsString('Symfony\Component\Form\Extension\Core\Type\FormType (method)', $tester->getDisplay());
     }
 
     public function testDebugSingleFormTypeNotFound()
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/CountryTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/CountryTypeTest.php
index 8c72b46bbc..9cadc9cd74 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/CountryTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/CountryTypeTest.php
@@ -32,11 +32,11 @@ class CountryTypeTest extends BaseTypeTest
             ->createView()->vars['choices'];
 
         // Don't check objects for identity
-        $this->assertContains(new ChoiceView('DE', 'DE', 'Germany'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('GB', 'GB', 'United Kingdom'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('US', 'US', 'United States'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('FR', 'FR', 'France'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('MY', 'MY', 'Malaysia'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('DE', 'DE', 'Germany'), $choices);
+        $this->assertContainsEquals(new ChoiceView('GB', 'GB', 'United Kingdom'), $choices);
+        $this->assertContainsEquals(new ChoiceView('US', 'US', 'United States'), $choices);
+        $this->assertContainsEquals(new ChoiceView('FR', 'FR', 'France'), $choices);
+        $this->assertContainsEquals(new ChoiceView('MY', 'MY', 'Malaysia'), $choices);
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/CurrencyTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/CurrencyTypeTest.php
index a02bae031a..7a8c1509ba 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/CurrencyTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/CurrencyTypeTest.php
@@ -31,9 +31,9 @@ class CurrencyTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE)
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('EUR', 'EUR', 'Euro'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('USD', 'USD', 'US Dollar'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('SIT', 'SIT', 'Slovenian Tolar'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('EUR', 'EUR', 'Euro'), $choices);
+        $this->assertContainsEquals(new ChoiceView('USD', 'USD', 'US Dollar'), $choices);
+        $this->assertContainsEquals(new ChoiceView('SIT', 'SIT', 'Slovenian Tolar'), $choices);
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/LanguageTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/LanguageTypeTest.php
index 7f25c8dab7..960aef1994 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/LanguageTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/LanguageTypeTest.php
@@ -31,11 +31,11 @@ class LanguageTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE)
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('en', 'en', 'English'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('en_GB', 'en_GB', 'British English'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('en_US', 'en_US', 'American English'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('fr', 'fr', 'French'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('my', 'my', 'Burmese'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('en', 'en', 'English'), $choices);
+        $this->assertContainsEquals(new ChoiceView('en_GB', 'en_GB', 'British English'), $choices);
+        $this->assertContainsEquals(new ChoiceView('en_US', 'en_US', 'American English'), $choices);
+        $this->assertContainsEquals(new ChoiceView('fr', 'fr', 'French'), $choices);
+        $this->assertContainsEquals(new ChoiceView('my', 'my', 'Burmese'), $choices);
     }
 
     /**
@@ -61,7 +61,7 @@ class LanguageTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE, 'language')
             ->createView()->vars['choices'];
 
-        $this->assertNotContains(new ChoiceView('mul', 'mul', 'Mehrsprachig'), $choices, '', false, false);
+        $this->assertNotContainsEquals(new ChoiceView('mul', 'mul', 'Mehrsprachig'), $choices);
     }
 
     public function testSubmitNull($expected = null, $norm = null, $view = null)
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/LocaleTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/LocaleTypeTest.php
index 484d9cede8..c5ba0da691 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/LocaleTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/LocaleTypeTest.php
@@ -31,9 +31,9 @@ class LocaleTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE)
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('en', 'en', 'English'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('en_GB', 'en_GB', 'English (United Kingdom)'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('zh_Hant_HK', 'zh_Hant_HK', 'Chinese (Traditional, Hong Kong SAR China)'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('en', 'en', 'English'), $choices);
+        $this->assertContainsEquals(new ChoiceView('en_GB', 'en_GB', 'English (United Kingdom)'), $choices);
+        $this->assertContainsEquals(new ChoiceView('zh_Hant_HK', 'zh_Hant_HK', 'Chinese (Traditional, Hong Kong SAR China)'), $choices);
     }
 
     /**
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimezoneTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimezoneTypeTest.php
index 2d1fadf7d2..e205529fe8 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimezoneTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/TimezoneTypeTest.php
@@ -23,8 +23,8 @@ class TimezoneTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE)
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('Africa/Kinshasa', 'Africa/Kinshasa', 'Africa / Kinshasa'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('America/New_York', 'America/New_York', 'America / New York'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('Africa/Kinshasa', 'Africa/Kinshasa', 'Africa / Kinshasa'), $choices);
+        $this->assertContainsEquals(new ChoiceView('America/New_York', 'America/New_York', 'America / New York'), $choices);
     }
 
     public function testSubmitNull($expected = null, $norm = null, $view = null)
@@ -69,7 +69,7 @@ class TimezoneTypeTest extends BaseTypeTest
         $form->submit('Europe/Saratov');
 
         $this->assertEquals(new \DateTimeZone('Europe/Saratov'), $form->getData());
-        $this->assertContains('Europe/Saratov', $form->getConfig()->getAttribute('choice_list')->getValues());
+        $this->assertStringContainsString('Europe/Saratov', $form->getConfig()->getAttribute('choice_list')->getValues());
     }
 
     /**
@@ -81,7 +81,7 @@ class TimezoneTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE, null, ['regions' => \DateTimeZone::EUROPE])
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'Europe / Amsterdam'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'Europe / Amsterdam'), $choices);
     }
 
     /**
@@ -170,8 +170,8 @@ class TimezoneTypeTest extends BaseTypeTest
         $choices = $this->factory->create(static::TESTED_TYPE, null, ['intl' => true])
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'Central European Time (Amsterdam)'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('Etc/UTC', 'Etc/UTC', 'Coordinated Universal Time'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'Central European Time (Amsterdam)'), $choices);
+        $this->assertContainsEquals(new ChoiceView('Etc/UTC', 'Etc/UTC', 'Coordinated Universal Time'), $choices);
     }
 
     /**
@@ -186,8 +186,8 @@ class TimezoneTypeTest extends BaseTypeTest
             ])
             ->createView()->vars['choices'];
 
-        $this->assertContains(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'за центральноєвропейським часом (Амстердам)'), $choices, '', false, false);
-        $this->assertContains(new ChoiceView('Etc/UTC', 'Etc/UTC', 'за всесвітнім координованим часом'), $choices, '', false, false);
+        $this->assertContainsEquals(new ChoiceView('Europe/Amsterdam', 'Europe/Amsterdam', 'за центральноєвропейським часом (Амстердам)'), $choices);
+        $this->assertContainsEquals(new ChoiceView('Etc/UTC', 'Etc/UTC', 'за всесвітнім координованим часом'), $choices);
     }
 
     public function testChoiceTranslationLocaleOptionWithoutIntl()
diff --git a/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
index b4e5a26407..ab527b6999 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
@@ -261,7 +261,7 @@ class BinaryFileResponseTest extends ResponseTestCase
         $this->expectOutputString('');
         $response->sendContent();
 
-        $this->assertContains('README.md', $response->headers->get('X-Sendfile'));
+        $this->assertStringContainsString('README.md', $response->headers->get('X-Sendfile'));
     }
 
     public function provideXSendfileFiles()
diff --git a/src/Symfony/Component/HttpFoundation/Tests/CookieTest.php b/src/Symfony/Component/HttpFoundation/Tests/CookieTest.php
index eaea69a7d9..61a278e656 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/CookieTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/CookieTest.php
@@ -116,7 +116,7 @@ class CookieTest extends TestCase
         $cookie = Cookie::create('foo', 'bar', $value);
         $expire = strtotime($value);
 
-        $this->assertEquals($expire, $cookie->getExpiresTime(), '->getExpiresTime() returns the expire date', 1);
+        $this->assertEqualsWithDelta($expire, $cookie->getExpiresTime(), 1, '->getExpiresTime() returns the expire date');
     }
 
     public function testGetDomain()
diff --git a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
index d7b8f2d78b..414868925a 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
@@ -1630,14 +1630,14 @@ class RequestTest extends TestCase
 
         $asString = (string) $request;
 
-        $this->assertContains('Accept-Language: zh, en-us; q=0.8, en; q=0.6', $asString);
-        $this->assertContains('Cookie: Foo=Bar', $asString);
+        $this->assertStringContainsString('Accept-Language: zh, en-us; q=0.8, en; q=0.6', $asString);
+        $this->assertStringContainsString('Cookie: Foo=Bar', $asString);
 
         $request->cookies->set('Another', 'Cookie');
 
         $asString = (string) $request;
 
-        $this->assertContains('Cookie: Foo=Bar; Another=Cookie', $asString);
+        $this->assertStringContainsString('Cookie: Foo=Bar; Another=Cookie', $asString);
     }
 
     public function testIsMethod()
diff --git a/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
index 24f5df1c40..8609fa7231 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php
@@ -601,7 +601,7 @@ class ResponseTest extends ResponseTestCase
             $this->fail('->setCache() throws an InvalidArgumentException if an option is not supported');
         } catch (\Exception $e) {
             $this->assertInstanceOf('InvalidArgumentException', $e, '->setCache() throws an InvalidArgumentException if an option is not supported');
-            $this->assertContains('"wrong option"', $e->getMessage());
+            $this->assertStringContainsString('"wrong option"', $e->getMessage());
         }
 
         $options = ['etag' => '"whatever"'];
@@ -654,7 +654,7 @@ class ResponseTest extends ResponseTestCase
         ob_start();
         $response->sendContent();
         $string = ob_get_clean();
-        $this->assertContains('test response rendering', $string);
+        $this->assertStringContainsString('test response rendering', $string);
     }
 
     public function testSetPublic()
diff --git a/src/Symfony/Component/HttpKernel/Tests/EventListener/RouterListenerTest.php b/src/Symfony/Component/HttpKernel/Tests/EventListener/RouterListenerTest.php
index a9440630e6..68b00a027c 100644
--- a/src/Symfony/Component/HttpKernel/Tests/EventListener/RouterListenerTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/EventListener/RouterListenerTest.php
@@ -199,7 +199,7 @@ class RouterListenerTest extends TestCase
         $request = Request::create('http://localhost/');
         $response = $kernel->handle($request);
         $this->assertSame(404, $response->getStatusCode());
-        $this->assertContains('Welcome', $response->getContent());
+        $this->assertStringContainsString('Welcome', $response->getContent());
     }
 
     public function testRequestWithBadHost()
diff --git a/src/Symfony/Component/HttpKernel/Tests/UriSignerTest.php b/src/Symfony/Component/HttpKernel/Tests/UriSignerTest.php
index 9b7fe08a99..b2eb59206b 100644
--- a/src/Symfony/Component/HttpKernel/Tests/UriSignerTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/UriSignerTest.php
@@ -20,9 +20,9 @@ class UriSignerTest extends TestCase
     {
         $signer = new UriSigner('foobar');
 
-        $this->assertContains('?_hash=', $signer->sign('http://example.com/foo'));
-        $this->assertContains('?_hash=', $signer->sign('http://example.com/foo?foo=bar'));
-        $this->assertContains('&foo=', $signer->sign('http://example.com/foo?foo=bar'));
+        $this->assertStringContainsString('?_hash=', $signer->sign('http://example.com/foo'));
+        $this->assertStringContainsString('?_hash=', $signer->sign('http://example.com/foo?foo=bar'));
+        $this->assertStringContainsString('&foo=', $signer->sign('http://example.com/foo?foo=bar'));
     }
 
     public function testCheck()
diff --git a/src/Symfony/Component/Intl/Tests/NumberFormatter/AbstractNumberFormatterTest.php b/src/Symfony/Component/Intl/Tests/NumberFormatter/AbstractNumberFormatterTest.php
index 464a0aac0c..9e8499eba9 100644
--- a/src/Symfony/Component/Intl/Tests/NumberFormatter/AbstractNumberFormatterTest.php
+++ b/src/Symfony/Component/Intl/Tests/NumberFormatter/AbstractNumberFormatterTest.php
@@ -806,7 +806,7 @@ abstract class AbstractNumberFormatterTest extends TestCase
     {
         $formatter = $this->getNumberFormatter('en', NumberFormatter::DECIMAL);
         $parsedValue = $formatter->parse($value, NumberFormatter::TYPE_DOUBLE);
-        $this->assertEquals($expectedValue, $parsedValue, '', 0.001);
+        $this->assertEqualsWithDelta($expectedValue, $parsedValue, 0.001);
     }
 
     public function parseTypeDoubleProvider()
diff --git a/src/Symfony/Component/Process/Tests/PhpProcessTest.php b/src/Symfony/Component/Process/Tests/PhpProcessTest.php
index 0355c85be6..b7b21ebcb1 100644
--- a/src/Symfony/Component/Process/Tests/PhpProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/PhpProcessTest.php
@@ -39,10 +39,10 @@ PHP
         $commandLine = $process->getCommandLine();
 
         $process->start();
-        $this->assertContains($commandLine, $process->getCommandLine(), '::getCommandLine() returns the command line of PHP after start');
+        $this->assertStringContainsString($commandLine, $process->getCommandLine(), '::getCommandLine() returns the command line of PHP after start');
 
         $process->wait();
-        $this->assertContains($commandLine, $process->getCommandLine(), '::getCommandLine() returns the command line of PHP after wait');
+        $this->assertStringContainsString($commandLine, $process->getCommandLine(), '::getCommandLine() returns the command line of PHP after wait');
 
         $this->assertSame(PHP_VERSION.\PHP_SAPI, $process->getOutput());
     }
diff --git a/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/UserAuthenticationProviderTest.php b/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/UserAuthenticationProviderTest.php
index 9d789e5fde..8ec92d5014 100644
--- a/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/UserAuthenticationProviderTest.php
+++ b/src/Symfony/Component/Security/Core/Tests/Authentication/Provider/UserAuthenticationProviderTest.php
@@ -211,8 +211,8 @@ class UserAuthenticationProviderTest extends TestCase
 
         $this->assertInstanceOf('Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken', $authToken);
         $this->assertSame($user, $authToken->getUser());
-        $this->assertContains('ROLE_FOO', $authToken->getRoleNames(), '', false, false);
-        $this->assertContains($switchUserRole, $authToken->getRoles(), '', false, false);
+        $this->assertContains('ROLE_FOO', $authToken->getRoleNames());
+        $this->assertContains($switchUserRole, $authToken->getRoles());
         $this->assertEquals('foo', $authToken->getCredentials());
         $this->assertEquals(['foo' => 'bar'], $authToken->getAttributes(), '->authenticate() copies token attributes');
     }
@@ -240,7 +240,7 @@ class UserAuthenticationProviderTest extends TestCase
         $this->assertInstanceOf(SwitchUserToken::class, $authToken);
         $this->assertSame($originalToken, $authToken->getOriginalToken());
         $this->assertSame($user, $authToken->getUser());
-        $this->assertContains('ROLE_FOO', $authToken->getRoleNames(), '', false, false);
+        $this->assertContains('ROLE_FOO', $authToken->getRoleNames());
         $this->assertEquals('foo', $authToken->getCredentials());
         $this->assertEquals(['foo' => 'bar'], $authToken->getAttributes(), '->authenticate() copies token attributes');
     }
diff --git a/src/Symfony/Component/Stopwatch/Tests/StopwatchEventTest.php b/src/Symfony/Component/Stopwatch/Tests/StopwatchEventTest.php
index c8ab4f0bea..ca28b58fe6 100644
--- a/src/Symfony/Component/Stopwatch/Tests/StopwatchEventTest.php
+++ b/src/Symfony/Component/Stopwatch/Tests/StopwatchEventTest.php
@@ -73,7 +73,7 @@ class StopwatchEventTest extends TestCase
         $event->start();
         usleep(200000);
         $event->stop();
-        $this->assertEquals(200, $event->getDuration(), '', self::DELTA);
+        $this->assertEqualsWithDelta(200, $event->getDuration(), self::DELTA);
 
         $event = new StopwatchEvent(microtime(true) * 1000);
         $event->start();
@@ -83,7 +83,7 @@ class StopwatchEventTest extends TestCase
         $event->start();
         usleep(100000);
         $event->stop();
-        $this->assertEquals(200, $event->getDuration(), '', self::DELTA);
+        $this->assertEqualsWithDelta(200, $event->getDuration(), self::DELTA);
     }
 
     public function testDurationBeforeStop()
@@ -91,7 +91,7 @@ class StopwatchEventTest extends TestCase
         $event = new StopwatchEvent(microtime(true) * 1000);
         $event->start();
         usleep(200000);
-        $this->assertEquals(200, $event->getDuration(), '', self::DELTA);
+        $this->assertEqualsWithDelta(200, $event->getDuration(), self::DELTA);
 
         $event = new StopwatchEvent(microtime(true) * 1000);
         $event->start();
@@ -100,7 +100,7 @@ class StopwatchEventTest extends TestCase
         usleep(50000);
         $event->start();
         usleep(100000);
-        $this->assertEquals(100, $event->getDuration(), '', self::DELTA);
+        $this->assertEqualsWithDelta(100, $event->getDuration(), self::DELTA);
     }
 
     public function testStopWithoutStart()
@@ -132,7 +132,7 @@ class StopwatchEventTest extends TestCase
         $event->start();
         usleep(100000);
         $event->ensureStopped();
-        $this->assertEquals(300, $event->getDuration(), '', self::DELTA);
+        $this->assertEqualsWithDelta(300, $event->getDuration(), self::DELTA);
     }
 
     public function testStartTime()
@@ -149,7 +149,7 @@ class StopwatchEventTest extends TestCase
         $event->start();
         usleep(100000);
         $event->stop();
-        $this->assertEquals(0, $event->getStartTime(), '', self::DELTA);
+        $this->assertEqualsWithDelta(0, $event->getStartTime(), self::DELTA);
     }
 
     public function testHumanRepresentation()
diff --git a/src/Symfony/Component/Yaml/Tests/Command/LintCommandTest.php b/src/Symfony/Component/Yaml/Tests/Command/LintCommandTest.php
index f257a36361..a75c5f9f5a 100644
--- a/src/Symfony/Component/Yaml/Tests/Command/LintCommandTest.php
+++ b/src/Symfony/Component/Yaml/Tests/Command/LintCommandTest.php
@@ -60,7 +60,7 @@ bar';
         $ret = $tester->execute(['filename' => $filename], ['decorated' => false]);
 
         $this->assertEquals(1, $ret, 'Returns 1 in case of error');
-        $this->assertContains('Unable to parse at line 3 (near "bar").', trim($tester->getDisplay()));
+        $this->assertStringContainsString('Unable to parse at line 3 (near "bar").', trim($tester->getDisplay()));
     }
 
     public function testConstantAsKey()
diff --git a/src/Symfony/Component/Yaml/Tests/InlineTest.php b/src/Symfony/Component/Yaml/Tests/InlineTest.php
index 7f4959e95c..1b899fd54e 100644
--- a/src/Symfony/Component/Yaml/Tests/InlineTest.php
+++ b/src/Symfony/Component/Yaml/Tests/InlineTest.php
@@ -101,7 +101,7 @@ class InlineTest extends TestCase
             }
 
             $this->assertEquals('1.2', Inline::dump(1.2));
-            $this->assertContains('fr', strtolower(setlocale(LC_NUMERIC, 0)));
+            $this->assertStringContainsStringIgnoringCase('fr', setlocale(LC_NUMERIC, 0));
         } finally {
             setlocale(LC_NUMERIC, $locale);
         }