Adds tests for #202

This patch adds a test (using a test asset extending the `CreditCard`
validator) to cover the changes in #202. In doing so, I discovered the
logic in `CreditCard::addType()` was incorrectly storing the type
provided to the method, and not the constant _value_, which is what
`isValid()` assumes it to be in order to perform lookups in the other
class members.

Author: weierophinney

src/CreditCard.php

@@ -203,13 +203,20 @@ public function addType($type)
         }
 
         foreach ($type as $typ) {
-            if (defined('static::' . strtoupper($typ)) && ! in_array($typ, $this->options['type'])) {
-                $this->options['type'][] = $typ;
-            }
-
             if (($typ == self::ALL)) {
                 $this->options['type'] = array_keys($this->cardLength);
+                continue;
+            }
+
+            if (in_array($typ, $this->options['type'])) {
+                continue;
+            }
+
+            $constant = 'static::' . strtoupper($typ);
+            if (! defined($constant) || in_array(constant($constant), $this->options['type'])) {
+                continue;
             }
+            $this->options['type'][] = constant($constant);
         }
 
         return $this;

test/CreditCardTest.php

@@ -331,6 +331,16 @@ public function testEqualsMessageTemplates()
         );
     }
 
+    /**
+     * @see https://github.com/zendframework/zend-validator/pull/202
+     */
+    public function testValidatorAllowsExtensionsToDefineAdditionalTypesViaConstants()
+    {
+        $validator = new TestAsset\CreditCardValidatorExtension();
+        $this->assertSame($validator, $validator->addType('test_type'));
+        $this->assertContains(TestAsset\CreditCardValidatorExtension::TEST_TYPE, $validator->getType());
+    }
+
     public static function staticCallback($value)
     {
         return false;

test/TestAsset/CreditCardValidatorExtension.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-validator for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-validator/blob/master/LICENSE.md New BSD License
+ */
+
+namespace ZendTest\Validator\TestAsset;
+
+use Zend\Validator\CreditCard;
+
+class CreditCardValidatorExtension extends CreditCard
+{
+    const TEST_TYPE = 'Test_Type';
+}