[#1666] RFC: add support for optional custom error message for Configuration Validation Errors

Definition/BaseNode.php

@@ -104,6 +104,26 @@ public function getInfo()
         return $this->getAttribute('info');
     }
 
+    /**
+     * Sets an error message.
+     *
+     * @param string $errorMessage
+     */
+    public function setErrorMessage($errorMessage)
+    {
+        $this->setAttribute('errorMessage', $errorMessage);
+    }
+
+    /**
+     * Returns error message.
+     *
+     * @return string The error message
+     */
+    public function getErrorMessage()
+    {
+        return $this->getAttribute('errorMessage');
+    }
+
     /**
      * Sets the example configuration for this node.
      *

Definition/Builder/NodeDefinition.php

@@ -76,6 +76,17 @@ public function info($info)
         return $this->attribute('info', $info);
     }
 
+    /**
+     * Sets error message.
+     *
+     * @param string $errorMessage The error message text
+     * @return NodeDefinition
+     */
+    public function errorMessage($errorMessage)
+    {
+        return $this->attribute('errorMessage', $errorMessage);
+    }
+
     /**
      * Sets example configuration.
      *

Definition/ScalarNode.php

@@ -34,11 +34,17 @@ class ScalarNode extends VariableNode
     protected function validateType($value)
     {
         if (!is_scalar($value) && null !== $value) {
-            $ex = new InvalidTypeException(sprintf(
+            $errorMessage = $this->getErrorMessage();
+            $finalMessage = sprintf(
                 'Invalid type for path "%s". Expected scalar, but got %s.',
                 $this->getPath(),
                 gettype($value)
-            ));
+            );
+            if ($errorMessage != null) {
+                $finalMessage .= sprintf("\nError message: %s.", $errorMessage);
+            }
+
+            $ex = new InvalidTypeException($finalMessage);
             $ex->setPath($this->getPath());
 
             throw $ex;

Definition/VariableNode.php

@@ -83,11 +83,17 @@ protected function validateType($value)
     protected function finalizeValue($value)
     {
         if (!$this->allowEmptyValue && empty($value)) {
-            $ex = new InvalidConfigurationException(sprintf(
+            $errorMessage = $this->getErrorMessage();
+            $finalMessage = sprintf(
                 'The path "%s" cannot contain an empty value, but got %s.',
                 $this->getPath(),
                 json_encode($value)
-            ));
+            );
+            if ($errorMessage != null) {
+                $finalMessage .= sprintf("\nError message: %s.", $errorMessage);
+            }
+
+            $ex = new InvalidConfigurationException($finalMessage);
             $ex->setPath($this->getPath());
 
             throw $ex;

Tests/Definition/Builder/TreeBuilderTest.php

@@ -124,4 +124,21 @@ public function testDefinitionExampleGetsTransferedToNode()
         $this->assertTrue(is_array($tree->getExample()));
         $this->assertEquals('example', $children['child']->getExample());
     }
+
+    public function testDefinitionErrorMessageGetsTransferedToNode()
+    {
+        $builder = new TreeBuilder();
+
+        $builder->root('test')->errorMessage('You are missing the root node')
+            ->children()
+            ->node('child', 'variable')->errorMessage('child error message')->defaultValue('default')
+            ->end()
+            ->end();
+
+        $tree = $builder->buildTree();
+        $children = $tree->getChildren();
+
+        $this->assertEquals('You are missing the root node', $tree->getErrorMessage());
+        $this->assertEquals('child error message', $children['child']->getErrorMessage());
+    }
 }

Tests/Definition/ScalarNodeTest.php

@@ -57,4 +57,42 @@ public function getInvalidValues()
             array(new \stdClass()),
         );
     }
+
+    public function testNormalizeThrowsExceptionWithoutErrorMessage()
+    {
+        $value = array(array('foo' => 'bar'));
+        $node = new ScalarNode('test');
+
+        $expectedMessage = sprintf(
+            'Invalid type for path "%s". Expected scalar, but got %s.',
+            $node->getPath(),
+            gettype($value)
+        );
+
+        $this->setExpectedException(
+            'Symfony\Component\Config\Definition\Exception\InvalidTypeException', $expectedMessage
+        );
+
+        $node->normalize($value);
+    }
+
+    public function testNormalizeThrowsExceptionWithErrorMessage()
+    {
+        $value = array(array('foo' => 'bar'));
+        $node = new ScalarNode('test');
+        $node->setErrorMessage('This is a custom error message');
+
+        $expectedMessage = sprintf(
+            'Invalid type for path "%s". Expected scalar, but got %s.'.
+                "\nError message: ".$node->getErrorMessage(),
+            $node->getPath(),
+            gettype($value)
+        );
+
+        $this->setExpectedException(
+            'Symfony\Component\Config\Definition\Exception\InvalidTypeException', $expectedMessage
+        );
+
+        $node->normalize($value);
+    }
 }