bug #31084 [HttpFoundation] Make MimeTypeExtensionGuesser case insensitive (vermeirentony)

This PR was merged into the 3.4 branch.

Discussion
----------

[HttpFoundation] Make MimeTypeExtensionGuesser case insensitive

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

Some mime types have a camelCase word in them.
The Apache HTTPD project list items are all lower case.
So I suggest making the $mimeType string lowercase while checking the array key.
That way, we can keep the list in sync.

Example: xlsm file mime type is `application/vnd.ms-excel.sheet.macroEnabled.12`
The key that matches the xlsm extension in the `$defaultExtensions` array is `application/vnd.ms-excel.sheet.macroenabled.12`

Example xlsm file:
https://github.com/vermeirentony/xlsm-example

Commits
-------

e294ee6b9a Make MimeTypeExtensionGuesser case insensitive

src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeExtensionGuesser.php

@@ -808,6 +808,12 @@ class MimeTypeExtensionGuesser implements ExtensionGuesserInterface
      */
     public function guess($mimeType)
     {
-        return isset($this->defaultExtensions[$mimeType]) ? $this->defaultExtensions[$mimeType] : null;
+        if (isset($this->defaultExtensions[$mimeType])) {
+            return $this->defaultExtensions[$mimeType];
+        }
+
+        $lcMimeType = strtolower($mimeType);
+
+        return isset($this->defaultExtensions[$lcMimeType]) ? $this->defaultExtensions[$lcMimeType] : null;
     }
 }

src/Symfony/Component/HttpFoundation/Tests/File/UploadedFileTest.php

@@ -90,6 +90,19 @@ class UploadedFileTest extends TestCase
         $this->assertEquals('jpeg', $file->guessClientExtension());
     }
 
+    public function testCaseSensitiveMimeType()
+    {
+        $file = new UploadedFile(
+            __DIR__.'/Fixtures/case-sensitive-mime-type.xlsm',
+            'test.xlsm',
+            'application/vnd.ms-excel.sheet.macroEnabled.12',
+            filesize(__DIR__.'/Fixtures/case-sensitive-mime-type.xlsm'),
+            null
+        );
+
+        $this->assertEquals('xlsm', $file->guessClientExtension());
+    }
+
     public function testErrorIsOkByDefault()
     {
         $file = new UploadedFile(