diff --git a/tests/framework/db/ActiveQueryModelConnectionTest.php b/tests/framework/db/ActiveQueryModelConnectionTest.php
new file mode 100644
index 0000000000..fdef6d55b2
--- /dev/null
+++ b/tests/framework/db/ActiveQueryModelConnectionTest.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yiiunit\framework\db;
+
+use yii\db\ActiveQuery;
+use yii\db\ActiveRecord as DefaultActiveRecord;
+use yiiunit\data\ar\ActiveRecord;
+use yiiunit\TestCase;
+
+class ActiveQueryModelConnectionTest extends TestCase
+{
+    private $globalConnection;
+    private $modelConnection;
+
+    protected function setUp()
+    {
+        $this->globalConnection = $this->getMockBuilder('yii\db\Connection')->getMock();
+        $this->modelConnection = $this->getMockBuilder('yii\db\Connection')->getMock();
+
+        $this->mockApplication([
+            'components' => [
+                'db' => $this->globalConnection
+            ]
+        ]);
+
+        ActiveRecord::$db = $this->modelConnection;
+    }
+
+    private function prepareConnectionMock($connection)
+    {
+        $command = $this->getMockBuilder('yii\db\Command')->getMock();
+        $command->method('queryOne')->willReturn(false);
+        $connection->method('createCommand')->willReturn($command);
+        $builder = $this->getMockBuilder('yii\db\QueryBuilder')->disableOriginalConstructor()->getMock();
+        $connection->expects($this->once())->method('getQueryBuilder')->willReturn($builder);
+    }
+
+    public function testEnsureModelConnectionForOne()
+    {
+        $this->globalConnection->expects($this->never())->method('getQueryBuilder');
+        $this->prepareConnectionMock($this->modelConnection);
+
+        $query = new ActiveQuery(ActiveRecord::className());
+        $query->one();
+    }
+
+    public function testEnsureGlobalConnectionForOne()
+    {
+        $this->modelConnection->expects($this->never())->method('getQueryBuilder');
+        $this->prepareConnectionMock($this->globalConnection);
+
+        $query = new ActiveQuery(DefaultActiveRecord::className());
+        $query->one();
+    }
+
+    public function testEnsureModelConnectionForAll()
+    {
+        $this->globalConnection->expects($this->never())->method('getQueryBuilder');
+        $this->prepareConnectionMock($this->modelConnection);
+
+        $query = new ActiveQuery(ActiveRecord::className());
+        $query->all();
+    }
+
+    public function testEnsureGlobalConnectionForAll()
+    {
+        $this->modelConnection->expects($this->never())->method('getQueryBuilder');
+        $this->prepareConnectionMock($this->globalConnection);
+
+        $query = new ActiveQuery(DefaultActiveRecord::className());
+        $query->all();
+    }
+}