[8.x] Add --pretend option for model:prune command (laravel#38945)

* Add --pretend option for model:prune command

* Fix tests

* Fix code style

src/Illuminate/Database/Console/PruneCommand.php

@@ -19,7 +19,8 @@ class PruneCommand extends Command
      */
     protected $signature = 'model:prune
                                 {--model=* : Class names of the models to be pruned}
-                                {--chunk=1000 : The number of models to retrieve per chunk of models to be deleted}';
+                                {--chunk=1000 : The number of models to retrieve per chunk of models to be deleted}
+                                {--pretend : Display the number of prunable records found instead of deleting them}';
 
     /**
      * The console command description.
@@ -44,6 +45,14 @@ public function handle(Dispatcher $events)
             return;
         }
 
+        if ($this->option('pretend')) {
+            $models->each(function ($model) {
+                $this->pretendToPrune($model);
+            });
+
+            return;
+        }
+
         $events->listen(ModelsPruned::class, function ($event) {
             $this->info("{$event->count} [{$event->model}] records have been pruned.");
         });
@@ -104,4 +113,26 @@ protected function isPrunable($model)
 
         return in_array(Prunable::class, $uses) || in_array(MassPrunable::class, $uses);
     }
+
+    /**
+     * Display how many models will be pruned.
+     *
+     * @param  string  $model
+     * @return void
+     */
+    protected function pretendToPrune($model)
+    {
+        $instance = new $model;
+
+        $count = $instance->prunable()
+            ->when(in_array(SoftDeletes::class, class_uses_recursive(get_class($instance))), function ($query) {
+                $query->withTrashed();
+            })->count();
+
+        if ($count === 0) {
+            $this->info("No prunable [$model] records found.");
+        } else {
+            $this->info("{$count} [{$model}] records will be pruned.");
+        }
+    }
 }

tests/Database/PruneCommandTest.php

@@ -4,12 +4,15 @@
 
 use Illuminate\Container\Container;
 use Illuminate\Contracts\Events\Dispatcher as DispatcherContract;
+use Illuminate\Database\Capsule\Manager as DB;
+use Illuminate\Database\ConnectionResolverInterface;
 use Illuminate\Database\Console\PruneCommand;
 use Illuminate\Database\Eloquent\MassPrunable;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Prunable;
 use Illuminate\Database\Events\ModelsPruned;
 use Illuminate\Events\Dispatcher;
+use Mockery as m;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Console\Input\ArrayInput;
 use Symfony\Component\Console\Output\BufferedOutput;
@@ -60,6 +63,41 @@ public function testNonPrunableTest()
 EOF, str_replace("\r", '', $output->fetch()));
     }
 
+    public function testTheCommandMayBePretended()
+    {
+        $db = new DB;
+        $db->addConnection([
+            'driver' => 'sqlite',
+            'database' => ':memory:',
+        ]);
+        $db->setAsGlobal();
+        DB::connection('default')->getSchemaBuilder()->create('prunables', function ($table) {
+            $table->string('name')->nullable();
+            $table->string('value')->nullable();
+        });
+        DB::connection('default')->table('prunables')->insert([
+            ['name' => 'zain', 'value' => 1],
+            ['name' => 'patrice', 'value' => 2],
+            ['name' => 'amelia', 'value' => 3],
+            ['name' => 'stuart', 'value' => 4],
+            ['name' => 'bello', 'value' => 5],
+        ]);
+        $resolver = m::mock(ConnectionResolverInterface::class, ['connection' => $db->getConnection('default')]);
+        PrunableTestModelWithPrunableRecords::setConnectionResolver($resolver);
+
+        $output = $this->artisan([
+            '--model' => PrunableTestModelWithPrunableRecords::class,
+            '--pretend' => true,
+        ]);
+
+        $this->assertEquals(<<<'EOF'
+3 [Illuminate\Tests\Database\PrunableTestModelWithPrunableRecords] records will be pruned.
+
+EOF, str_replace("\r", '', $output->fetch()));
+
+        $this->assertEquals(5, PrunableTestModelWithPrunableRecords::count());
+    }
+
     protected function artisan($arguments)
     {
         $input = new ArrayInput($arguments);
@@ -84,13 +122,21 @@ class PrunableTestModelWithPrunableRecords extends Model
 {
     use MassPrunable;
 
+    protected $table = 'prunables';
+    protected $connection = 'default';
+
     public function pruneAll()
     {
         event(new ModelsPruned(static::class, 10));
         event(new ModelsPruned(static::class, 20));
 
         return 20;
     }
+
+    public function prunable()
+    {
+        return static::where('value', '>=', 3);
+    }
 }
 
 class PrunableTestModelWithoutPrunableRecords extends Model