Fix null title/description configuration (#1563 followup)

Author: abluchet

src/Bridge/Symfony/Bundle/DependencyInjection/Configuration.php

@@ -42,13 +42,19 @@ public function getConfigTreeBuilder()
             ->children()
                 ->scalarNode('title')
                     ->info('The title of the API.')
-                    ->cannotBeEmpty()
                     ->defaultValue('')
+                    ->beforeNormalization()
+                        ->ifNull()
+                        ->then(function ($v) { return ''; })
+                    ->end()
                 ->end()
                 ->scalarNode('description')
                     ->info('The description of the API.')
-                    ->cannotBeEmpty()
                     ->defaultValue('')
+                    ->beforeNormalization()
+                        ->ifNull()
+                        ->then(function ($v) { return ''; })
+                    ->end()
                 ->end()
                 ->scalarNode('version')
                     ->info('The version of the API.')

tests/Bridge/Symfony/Bundle/DependencyInjection/ConfigurationTest.php

@@ -234,4 +234,40 @@ public function testApiKeysConfig()
         $this->assertTrue(isset($config['swagger']['api_keys']));
         $this->assertSame($exampleConfig, $config['swagger']['api_keys'][0]);
     }
+
+    /**
+     * Test config for empty title and description.
+     */
+    public function testEmptyTitleDescriptionConfig()
+    {
+        $testConfig = [
+            'title' => '',
+            'description' => '',
+        ];
+
+        $config = $this->processor->processConfiguration($this->configuration, [
+            'api_platform' => $testConfig,
+        ]);
+
+        $this->assertSame($config['title'], '');
+        $this->assertSame($config['description'], '');
+    }
+
+    /**
+     * Test config for null title and description.
+     */
+    public function testNullTitleDescriptionConfig()
+    {
+        $testConfig = [
+            'title' => null,
+            'description' => null,
+        ];
+
+        $config = $this->processor->processConfiguration($this->configuration, [
+            'api_platform' => $testConfig,
+        ]);
+
+        $this->assertSame($config['title'], '');
+        $this->assertSame($config['description'], '');
+    }
 }