added assertNull() and assertNotNull()

tests/DoctrineTest/UnitTestCase.php

@@ -2,9 +2,9 @@
 class UnitTestCase
 {
     protected $_passed = 0;
-    
+
     protected $_failed = 0;
-    
+
     protected $_messages = array();
 
     public function assertEqual($value, $value2)
@@ -62,13 +62,32 @@ class UnitTestCase
             $this->_fail();
         }
     }
-    public function pass() 
+
+    public function assertNull($expr)
+    {
+        if (is_null($expr)) {
+            $this->pass();
+        } else {
+            $this->fail();
+        }
+    }
+
+    public function assertNotNull($expr)
+    {
+        if (is_null($expr)) {
+            $this->fail();
+        } else {
+            $this->pass();
+        }
+    }
+
+    public function pass()
     {
         $this->_passed++;
     }
     public function fail($message = "")
     {
-        $this->_fail($message);    
+        $this->_fail($message);
     }
     public function _fail($message = "")
     {
@@ -92,7 +111,7 @@ class UnitTestCase
         }
         $this->_failed++;
     }
-    public function run(DoctrineTest_Reporter $reporter = null, $filter = null) 
+    public function run(DoctrineTest_Reporter $reporter = null, $filter = null)
     {
         foreach (get_class_methods($this) as $method) {
             if (substr($method, 0, 4) === 'test') {
@@ -102,7 +121,7 @@ class UnitTestCase
             }
         }
     }
-    public function getMessages() 
+    public function getMessages()
     {
         return $this->_messages;
     }