feature #16906 [Console] Better support for one command app (lyrixx)

This PR was merged into the 3.2-dev branch.

Discussion
----------

[Console] Better support for one command app

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9564
| License       | MIT

Hello;

I write many CLI application, and "single command" in cli application is not so easy to write.
This is why I propose this patch. IMHO, this PR could replaces #9609.

See it in application:
```php
#!/usr/bin/env php
<?php

require __DIR__.'/vendor/autoload.php';

use Symfony\Component\Console\Application;
use Symfony\Component\Console\Input\InputArgument;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Input\InputOption;
use Symfony\Component\Console\Output\OutputInterface;

(new Application('echo', '1.0.0'))
    ->register('echo')
        ->addArgument('foo', InputArgument::OPTIONAL, 'The directory', 'foo')
        ->addOption('bar', null, InputOption::VALUE_REQUIRED, 'Foobar', 'bar')
        ->setCode(function(InputInterface $input, OutputInterface $output) {
            $output->writeln('start');
            $output->writeln($input->getArgument('foo'));
            $output->writeln($input->getOption('bar'));
        })
    ->getApplication()
    ->setSingleCommand('echo')
    ->run();
```

Some usage:
```
>(3)[{..}eg/dev/github.com/symfony/symfony](console-one-app) php test.php
start
foo
bar
```
```
>(3)[{..}eg/dev/github.com/symfony/symfony](console-one-app) php test.php  "first argument"
start
first argument
bar
```
```
>(3)[{..}eg/dev/github.com/symfony/symfony](console-one-app) php test.php  "first argument" --bar="first option"
start
first argument
first option
```
```
>(3)[{..}eg/dev/github.com/symfony/symfony](console-one-app) php test.php  "first argument" --bar="first option" --help
Usage:
  echo [options] [--] [<foo>]

Arguments:
  foo                   The directory [default: "foo"]

Options:
      --bar=BAR         Foobar [default: "bar"]
  -h, --help            Display this help message
  -q, --quiet           Do not output any message
  -V, --version         Display this application version
      --ansi            Force ANSI output
      --no-ansi         Disable ANSI output
  -n, --no-interaction  Do not ask any interactive question
  -v|vv|vvv, --verbose  Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
```

Commits
-------

4a9bb1d [Console] Better support for one command app

src/Symfony/Component/Console/Application.php

@@ -66,6 +66,7 @@ class Application
     private $dispatcher;
     private $terminalDimensions;
     private $defaultCommand;
+    private $singleCommand;
 
     /**
      * Constructor.
@@ -168,7 +169,7 @@ class Application
         if (true === $input->hasParameterOption(array('--help', '-h'), true)) {
             if (!$name) {
                 $name = 'help';
-                $input = new ArrayInput(array('command' => 'help'));
+                $input = new ArrayInput(array('command_name' => $this->defaultCommand));
             } else {
                 $this->wantHelps = true;
             }
@@ -226,6 +227,13 @@ class Application
      */
     public function getDefinition()
     {
+        if ($this->singleCommand) {
+            $inputDefinition = $this->definition;
+            $inputDefinition->setArguments();
+
+            return $inputDefinition;
+        }
+
         return $this->definition;
     }
 
@@ -859,7 +867,7 @@ class Application
      */
     protected function getCommandName(InputInterface $input)
     {
-        return $input->getFirstArgument();
+        return $this->singleCommand ? $this->defaultCommand : $input->getFirstArgument();
     }
 
     /**
@@ -1039,11 +1047,21 @@ class Application
     /**
      * Sets the default Command name.
      *
-     * @param string $commandName The Command name
+     * @param string $commandName     The Command name
+     * @param bool   $isSingleCommand Set to true if there is only one command in this application
      */
-    public function setDefaultCommand($commandName)
+    public function setDefaultCommand($commandName, $isSingleCommand = false)
     {
         $this->defaultCommand = $commandName;
+
+        if ($isSingleCommand) {
+            // Ensure the command exist
+            $this->find($commandName);
+
+            $this->singleCommand = true;
+        }
+
+        return $this;
     }
 
     private function stringWidth($string)

src/Symfony/Component/Console/Tests/ApplicationTest.php

@@ -1086,6 +1086,24 @@ class ApplicationTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals('interact called'.PHP_EOL.'called'.PHP_EOL, $tester->getDisplay(), 'Application runs the default set command if different from \'list\' command');
     }
 
+    public function testSetRunCustomSingleCommand()
+    {
+        $command = new \FooCommand();
+
+        $application = new Application();
+        $application->setAutoExit(false);
+        $application->add($command);
+        $application->setDefaultCommand($command->getName(), true);
+
+        $tester = new ApplicationTester($application);
+
+        $tester->run(array());
+        $this->assertContains('called', $tester->getDisplay());
+
+        $tester->run(array('--help' => true));
+        $this->assertContains('The foo:bar command', $tester->getDisplay());
+    }
+
     /**
      * @requires function posix_isatty
      */

src/Symfony/Component/Console/Tests/Fixtures/application_run2.txt

@@ -1,28 +1,26 @@
 Usage:
-  help [options] [--] [<command_name>]
+  list [options] [--] [<namespace>]
 
 Arguments:
-  command               The command to execute
-  command_name          The command name [default: "help"]
+  namespace            The namespace name
 
 Options:
-      --format=FORMAT   The output format (txt, xml, json, or md) [default: "txt"]
-      --raw             To output raw command help
-  -h, --help            Display this help message
-  -q, --quiet           Do not output any message
-  -V, --version         Display this application version
-      --ansi            Force ANSI output
-      --no-ansi         Disable ANSI output
-  -n, --no-interaction  Do not ask any interactive question
-  -v|vv|vvv, --verbose  Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
+      --raw            To output raw command list
+      --format=FORMAT  The output format (txt, xml, json, or md) [default: "txt"]
 
 Help:
- The help command displays help for a given command:
+ The list command lists all commands:
  
-   php app/console help list
+   php app/console list
  
- You can also output the help in other formats by using the --format option:
+ You can also display the commands for a specific namespace:
  
-   php app/console help --format=xml list
+   php app/console list test
  
- To display the list of available commands, please use the list command.
+ You can also output the information in other formats by using the --format option:
+ 
+   php app/console list --format=xml
+ 
+ It's also possible to get raw list of commands (useful for embedding command runner):
+ 
+   php app/console list --raw