Refactored unit tests.

apps/basic/tests/unit/_bootstrap.php

 <?php
 
 // add unit testing specific bootstrap code here
-
-yii\codeception\TestCase::$appConfig = require(__DIR__ . '/_config.php');

extensions/yii/codeception/TestCase.php

@@ -17,12 +17,10 @@ class TestCase extends Test
 	/**
 	 * @var array|string the application configuration that will be used for creating an application instance for each test.
 	 * You can use a string to represent the file path or path alias of a configuration file.
+	 * The application configuration array may contain an optional `class` element which specifies the class
+	 * name of the application instance to be created. By default, a [[yii\web\Application]] instance will be created.
 	 */
-	public static $appConfig = [];
-	/**
-	 * @var string the application class that [[mockApplication()]] should use
-	 */
-	public static $appClass = 'yii\web\Application';
+	public $appConfig = '@tests/unit/_config.php';
 
 	/**
 	 * @inheritdoc
@@ -47,17 +45,26 @@ class TestCase extends Test
 	 * @param array $config the configuration that should be used to generate the application instance.
 	 * If null, [[appConfig]] will be used.
 	 * @return \yii\web\Application|\yii\console\Application the application instance
+	 * @throws InvalidConfigException if the application configuration is invalid
 	 */
 	protected function mockApplication($config = null)
 	{
-		$config = $config === null ? static::$appConfig : $config;
+		$config = $config === null ? $this->appConfig : $config;
 		if (is_string($config)) {
-			$config = Yii::getAlias($config);
+			$configFile = Yii::getAlias($config);
+			if (!is_file($configFile)) {
+				throw new InvalidConfigException("The application configuration file does not exist: $config");
+			}
+			$config = require($configFile);
 		}
-		if (!is_array($config)) {
-			throw new InvalidConfigException('Please provide a configuration for creating application.');
+		if (is_array($config)) {
+			if (!isset($config['class'])) {
+				$config['class'] = 'yii\web\Application';
+			}
+			return Yii::createObject($config);
+		} else {
+			throw new InvalidConfigException('Please provide a configuration array to mock up an application.');
 		}
-		return new static::$appClass($config);
 	}
 
 	/**

framework/yii/test/DbFixtureManager.php

@@ -10,7 +10,6 @@ namespace yii\test;
 use Yii;
 use yii\base\Component;
 use yii\base\InvalidConfigException;
-use yii\db\ActiveRecord;
 use yii\db\ActiveRecordInterface;
 use yii\db\Connection;
 
@@ -185,7 +184,7 @@ class DbFixtureManager extends Component
 	 * Returns the specified ActiveRecord instance in the fixture data.
 	 * @param string $fixtureName the fixture name
 	 * @param string $modelName the alias for the fixture data row
-	 * @return \yii\db\ActiveRecord the ActiveRecord instance. Null is returned if there is no such fixture row.
+	 * @return ActiveRecordInterface the ActiveRecord instance. Null is returned if there is no such fixture row.
 	 */
 	public function getModel($fixtureName, $modelName)
 	{
@@ -196,9 +195,9 @@ class DbFixtureManager extends Component
 			return $this->_models[$fixtureName][$modelName];
 		}
 		$row = $this->_rows[$fixtureName][$modelName];
-		/** @var \yii\db\ActiveRecord $modelClass */
+		/** @var ActiveRecordInterface $modelClass */
 		$modelClass = $this->_models[$fixtureName];
-		/** @var \yii\db\ActiveRecord $model */
+		/** @var ActiveRecordInterface $model */
 		$model = new $modelClass;
 		$keys = [];
 		foreach ($model->primaryKey() as $key) {

framework/yii/test/DbTestTrait.php

@@ -19,15 +19,18 @@ use Yii;
  *
  * ~~~
  * use yii\test\DbTestTrait;
+ * use yii\codeception\TestCase;
  * use app\models\Post;
  * use app\models\User;
  *
- * class PostTestCase extends \PHPUnit_Framework_TestCase
+ * class PostTestCase extends TestCase
  * {
  *     use DbTestTrait;
  *
- *     public function setUp()
+ *     protected function setUp()
  *     {
+ *         parent::setUp();
+ *
  *         $this->loadFixtures([
  *             'posts' => Post::className(),
  *             'users' => User::className(),