Fixed validation failure messages for required input

- Updates the test case to create an assertion method; the method now uses
  `getOption('messageTemplates')` instead of reflection to be less brittle, and
  is used in two separate test methods.
- Updated `Input` to add a `prepareRequiredValidationFailureMessage()` method
  taht creates the required message format. Each of `Input`, `ArrayInput`, and
  `FileInput` now assign the return of that method to the `$errorMessage`
  property directly.

Author: weierophinney

src/ArrayInput.php

@@ -71,7 +71,7 @@ public function isValid($context = null)
 
         if (! $hasValue && $required) {
             if ($this->errorMessage === null) {
-                $this->setErrorMessage('Value is required');
+                $this->errorMessage = $this->prepareRequiredValidationFailureMessage();
             }
             return false;
         }

src/FileInput.php

@@ -125,7 +125,7 @@ public function isValid($context = null)
 
         if (! $hasValue && $required && ! $this->hasFallback()) {
             if ($this->errorMessage === null) {
-                $this->setErrorMessage('Value is required');
+                $this->errorMessage = $this->prepareRequiredValidationFailureMessage();
             }
             return false;
         }

src/Input.php

@@ -404,7 +404,7 @@ public function isValid($context = null)
 
         if (! $hasValue && $required) {
             if ($this->errorMessage === null) {
-                $this->setErrorMessage('Value is required');
+                $this->errorMessage = $this->prepareRequiredValidationFailureMessage();
             }
             return false;
         }
@@ -483,4 +483,18 @@ protected function injectNotEmptyValidator()
 
         $chain->prependValidator(new NotEmpty(), true);
     }
+
+    /**
+     * Create and return the validation failure message for required input.
+     *
+     * @return string[]
+     */
+    protected function prepareRequiredValidationFailureMessage()
+    {
+        $notEmpty = new NotEmpty();
+        $templates = $notEmpty->getOption('messageTemplates');
+        return [
+            NotEmpty::IS_EMPTY => $templates[NotEmpty::IS_EMPTY],
+        ];
+    }
 }

test/InputTest.php

@@ -11,7 +11,6 @@
 
 use PHPUnit_Framework_MockObject_MockObject as MockObject;
 use PHPUnit_Framework_TestCase as TestCase;
-use ReflectionProperty;
 use stdClass;
 use Zend\Filter;
 use Zend\Filter\FilterChain;
@@ -36,6 +35,24 @@ public function setUp()
         $this->input = new Input('foo');
     }
 
+    public function assertRequiredValidationErrorMessage($input, $message = '')
+    {
+        $message  = $message ?: 'Expected failure message for required input';
+        $message .= ';';
+
+        $messages = $input->getMessages();
+        $this->assertInternalType('array', $messages, $message . ' non-array messages array');
+        $this->assertArrayHasKey(NotEmpty::IS_EMPTY, $messages, $message . ' missing NotEmpty::IS_EMPTY key');
+
+        $notEmpty         = new NotEmpty();
+        $messageTemplates = $notEmpty->getOption('messageTemplates');
+        $this->assertEquals(
+            $messageTemplates[NotEmpty::IS_EMPTY],
+            $messages[NotEmpty::IS_EMPTY],
+            $message . ' NotEmpty::IS_EMPTY message differs'
+        );
+    }
+
     public function testConstructorRequiresAName()
     {
         $this->assertEquals('foo', $this->input->getName());
@@ -174,7 +191,7 @@ public function testRequiredWithoutFallbackAndValueNotSetThenFail()
             $input->isValid(),
             'isValid() should be return always false when no fallback value, is required, and not data is set.'
         );
-        $this->assertEquals(['Value is required'], $input->getMessages(), 'getMessages() value not match');
+        $this->assertRequiredValidationErrorMessage($input);
     }
 
     /**
@@ -191,19 +208,7 @@ public function testRequiredWithoutFallbackAndValueNotSetProvidesNotEmptyValidat
             'isValid() should always return false when no fallback value is present, '
             . 'the input is required, and no data is set.'
         );
-        $messages = $input->getMessages();
-        $this->assertInternalType('array', $messages);
-        $this->assertArrayHasKey(NotEmpty::IS_EMPTY, $messages);
-
-        $notEmpty = new NotEmpty();
-        $r = new ReflectionProperty($notEmpty, 'messageTemplates');
-        $r->setAccessible(true);
-        $messageTemplates = $r->getValue($notEmpty);
-        $this->assertEquals(
-            $messageTemplates[NotEmpty::IS_EMPTY],
-            $messages[NotEmpty::IS_EMPTY],
-            'getMessages() values do not match'
-        );
+        $this->assertRequiredValidationErrorMessage($input);
     }
 
     public function testNotRequiredWithoutFallbackAndValueNotSetThenIsValid()