Adds a dry-run option

Author: raphaelstolt

README.md

@@ -201,11 +201,11 @@ cat .gitattributes | lean-package-validator validate --stdin-input
 The `create` command will create a `.gitattributes` file in the given directory. This command replaces the `--create` 
 option of the `validate` command. Please migrate to the dedicated commands.
 
-
 #### Update command
 
 The `update` command will update a present `.gitattributes` file in the given directory. This command replaces the `--overwrite`
-option of the `validate` command. Please migrate to the dedicated commands.
+option of the `validate` command. Please migrate to the dedicated commands. Like the above-mentioned `create` command it 
+provides a `--dry-run` option to see what the `.gitattributes` content would look like.
 
 #### Init command
 

src/Commands/CreateCommand.php

@@ -47,6 +47,12 @@ protected function configure(): void
         $this->addGenerationOptions(function (...$args) {
             $this->getDefinition()->addOption(new InputOption(...$args));
         });
+        $this->getDefinition()->addOption(new InputOption(
+            'dry-run',
+            null,
+            InputOption::VALUE_NONE,
+            'Do not write any files. Output the expected .gitattributes content'
+        ));
     }
 
     protected function execute(InputInterface $input, OutputInterface $output): int
@@ -61,7 +67,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 
         $gitattributesPath = $this->analyser->getGitattributesFilePath();
 
-        if (\file_exists($gitattributesPath)) {
+        if (\file_exists($gitattributesPath) && $input->getOption('dry-run') !== true) {
             $output->writeln('A .gitattributes file already exists. Use the update command to modify it.');
 
             return self::FAILURE;
@@ -75,6 +81,13 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             return self::FAILURE;
         }
 
+        // Support dry-run: print expected content and exit successfully without writing.
+        if ($input->getOption('dry-run') === true) {
+            $output->writeln($expected);
+
+            return self::SUCCESS;
+        }
+
         try {
             $this->repository->createGitattributesFile($expected);
         } catch (\Throwable $e) {

src/Commands/UpdateCommand.php

@@ -48,6 +48,13 @@ protected function configure(): void
             $this->getDefinition()->addOption(new InputOption(...$args));
         });
 
+        // Add dry-run option
+        $this->getDefinition()->addOption(new InputOption(
+            'dry-run',
+            null,
+            InputOption::VALUE_NONE,
+            'Do not write any files. Output the expected .gitattributes content'
+        ));
     }
 
     protected function execute(InputInterface $input, OutputInterface $output): int
@@ -62,7 +69,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 
         $gitattributesPath = $this->analyser->getGitattributesFilePath();
 
-        if (!\file_exists($gitattributesPath)) {
+        if (!\file_exists($gitattributesPath) && $input->getOption('dry-run') !== true) {
             $output->writeln('No .gitattributes file found. Use the <info>create</info> command to create one first.');
 
             return self::FAILURE;
@@ -76,6 +83,13 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             return self::FAILURE;
         }
 
+        // Support dry-run: print expected content and exit successfully without writing.
+        if ($input->getOption('dry-run') === true) {
+            $output->writeln($expected);
+
+            return self::SUCCESS;
+        }
+
         try {
             $this->repository->overwriteGitattributesFile($expected);
         } catch (\Throwable $e) {

tests/Commands/CreateCommandTest.php

@@ -67,6 +67,34 @@ public function createsNewGitattributesFileWithHeaderAndExpectedContent(): void
         $this->assertStringContainsString('export-ignore', $content);
     }
 
+    #[Test]
+    public function printsExpectedContentWithoutWritingAFile(): void
+    {
+        $analyser = (new Analyser(new Finder(new PhpPreset())))->setDirectory($this->temporaryDirectory);
+        $repository = new GitattributesFileRepository($analyser);
+        $command = new CreateCommand($analyser, $repository);
+
+        $artifactFilenames = ['README.md', '.gitignore'];
+
+        $this->createTemporaryFiles(
+            $artifactFilenames,
+            ['tests']
+        );
+
+        $result = TestCommand::for($command)
+            ->addArgument($this->temporaryDirectory)
+            ->addOption('dry-run')
+            ->execute()
+            ->assertSuccessful();
+
+        $output = $result->output();
+
+        $this->assertStringContainsString('export-ignore', $output);
+        $this->assertStringNotContainsString('has been created', $output);
+
+        $this->assertFileDoesNotExist($this->temporaryDirectory . DIRECTORY_SEPARATOR . '.gitattributes');
+    }
+
     #[Test]
     public function failsIfGitattributesAlreadyExists(): void
     {

tests/Commands/UpdateCommandTest.php

@@ -6,6 +6,7 @@
 
 use PHPUnit\Framework\Attributes\Test;
 use Stolt\LeanPackage\Analyser;
+use Stolt\LeanPackage\Commands\CreateCommand;
 use Stolt\LeanPackage\Commands\UpdateCommand;
 use Stolt\LeanPackage\GitattributesFileRepository;
 use Stolt\LeanPackage\Helpers\Str as OsHelper;
@@ -79,7 +80,6 @@ public function updatesExistingGitattributesAndReplacesHeader(): void
         $this->assertStringContainsString('tests/', $content);
         $this->assertStringContainsString('export-ignore', $content);
     }
-
     #[Test]
     public function failsWhenNoGitattributesFileIsPresent(): void
     {
@@ -100,4 +100,33 @@ public function failsWhenNoGitattributesFileIsPresent(): void
             ->assertFaulty()
             ->assertOutputContains('No .gitattributes file found. Use the create command to create one first.');
     }
+
+    #[Test]
+    public function printsExpectedContentWithoutWritingAFile(): void
+    {
+        $analyser = (new Analyser(new Finder(new PhpPreset())))->setDirectory($this->temporaryDirectory);
+        $repository = new GitattributesFileRepository($analyser);
+        $command = new UpdateCommand($analyser, $repository);
+
+        $artifactFilenames = ['README.md', '.gitignore', 'phpunit.xml.dist'];
+
+        $this->createTemporaryFiles(
+            $artifactFilenames,
+            ['tests']
+        );
+
+        $result = TestCommand::for($command)
+            ->addArgument($this->temporaryDirectory)
+            ->addOption('dry-run')
+            ->addOption('align-export-ignores')
+            ->execute()
+            ->assertSuccessful();
+
+        $output = $result->output();
+
+        $this->assertStringContainsString('export-ignore', $output);
+        $this->assertStringNotContainsString('has been updated', $output);
+
+        $this->assertFileDoesNotExist($this->temporaryDirectory . DIRECTORY_SEPARATOR . '.gitattributes');
+    }
 }