Validation warns if script description for nonexistent script is present

Fixes #7010

src/Composer/Util/ConfigValidator.php

@@ -118,6 +118,18 @@ class ConfigValidator
             }
         }
 
+        // report scripts-descriptions for non-existent scripts
+        $scriptsDescriptions = isset($manifest['scripts-descriptions']) ? $manifest['scripts-descriptions'] : array();
+        $scripts = isset($manifest['scripts']) ? $manifest['scripts'] : array();
+        foreach ($scriptsDescriptions as $scriptName => $scriptDescription) {
+            if (!array_key_exists($scriptName, $scripts)) {
+                $warnings[] = sprintf(
+                    'Description for non-existent script "%s" found in "scripts-descriptions"',
+                    $scriptName
+                );
+            }
+        }
+
         // check for empty psr-0/psr-4 namespace prefixes
         if (isset($manifest['autoload']['psr-0'][''])) {
             $warnings[] = "Defining autoload.psr-0 with an empty namespace prefix is a bad idea for performance";

tests/Composer/Test/Util/ConfigValidatorTest.php

@@ -34,4 +34,15 @@ class ConfigValidatorTest extends TestCase
             $warnings
         );
     }
+
+    public function testConfigValidatorWarnsOnScriptDescriptionForNonexistentScript()
+    {
+        $configValidator = new ConfigValidator(new NullIO());
+        list(, , $warnings) = $configValidator->validate(__DIR__ . '/Fixtures/composer_scripts-descriptions.json');
+
+        $this->assertContains(
+            'Description for non-existent script "phpcsxxx" found in "scripts-descriptions"',
+            $warnings
+        );
+    }
 }

tests/Composer/Test/Util/Fixtures/composer_scripts-descriptions.json

@@ -0,0 +1,10 @@
+{
+    "scripts": {
+        "test": "phpunit",
+        "phpcs": "phpcs --standard=PSR2 src"
+    },
+    "scripts-descriptions": {
+        "test": "Launches the preconfigured PHPUnit",
+        "phpcsxxx": "Checks that the application code conforms to coding standard"
+    }
+}