diff --git a/framework/data/ActiveDataProvider.php b/framework/data/ActiveDataProvider.php
index 44d547c..7f9d83c 100644
--- a/framework/data/ActiveDataProvider.php
+++ b/framework/data/ActiveDataProvider.php
@@ -88,9 +88,7 @@ class ActiveDataProvider extends BaseDataProvider
     public function init()
     {
         parent::init();
-        if ($this->db !== null) {
-            $this->db = Instance::ensure($this->db, Connection::className());
-        }
+        $this->db = Instance::ensure($this->db === null ? 'db' : $this->db, Connection::className());
     }
 
     /**
diff --git a/tests/framework/data/ActiveDataProviderCloningTest.php b/tests/framework/data/ActiveDataProviderCloningTest.php
index e4c7adc..836ce81 100644
--- a/tests/framework/data/ActiveDataProviderCloningTest.php
+++ b/tests/framework/data/ActiveDataProviderCloningTest.php
@@ -8,6 +8,7 @@
 namespace yiiunit\framework\data;
 
 use yii\data\ActiveDataProvider;
+use yii\db\Connection;
 use yii\db\Query;
 use yiiunit\TestCase;
 
@@ -19,15 +20,16 @@ class ActiveDataProviderCloningTest extends TestCase
     public function testClone()
     {
         $queryFirst = new Query();
-        
+
         $dataProviderFirst = new ActiveDataProvider([
+            'db' => new Connection(),
             'query' => $queryFirst
         ]);
-        
+
         $dataProviderSecond = clone $dataProviderFirst;
-        
+
         $querySecond = $dataProviderSecond->query;
-        
+
         $this->assertNotSame($querySecond, $queryFirst);
     }
 }
diff --git a/tests/framework/data/ActiveDataProviderTest.php b/tests/framework/data/ActiveDataProviderTest.php
index b496dcb..d87f106 100644
--- a/tests/framework/data/ActiveDataProviderTest.php
+++ b/tests/framework/data/ActiveDataProviderTest.php
@@ -35,6 +35,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
     public function testActiveQuery()
     {
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => Order::find()->orderBy('id'),
         ]);
         $orders = $provider->getModels();
@@ -45,6 +46,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         $this->assertEquals([1, 2, 3], $provider->getKeys());
 
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => Order::find(),
             'pagination' => [
                 'pageSize' => 2,
@@ -59,6 +61,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         /* @var $customer Customer */
         $customer = Customer::findOne(2);
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $customer->getOrders(),
         ]);
         $orders = $provider->getModels();
@@ -68,6 +71,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         $this->assertEquals([2, 3], $provider->getKeys());
 
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $customer->getOrders(),
             'pagination' => [
                 'pageSize' => 1,
@@ -82,6 +86,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         /* @var $order Order */
         $order = Order::findOne(2);
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $order->getItems(),
         ]);
         $items = $provider->getModels();
@@ -92,6 +97,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         $this->assertEquals([3, 4, 5], $provider->getKeys());
 
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $order->getItems(),
             'pagination' => [
                 'pageSize' => 2,
@@ -106,6 +112,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         /* @var $order Order */
         $order = Order::findOne(1);
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $order->getBooks(),
         ]);
         $items = $provider->getModels();
@@ -114,6 +121,7 @@ abstract class ActiveDataProviderTest extends DatabaseTestCase
         $this->assertInstanceOf(Item::className(), $items[1]);
 
         $provider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => $order->getBooks(),
             'pagination' => [
                 'pageSize' => 1,
diff --git a/tests/framework/widgets/LinkSorterTest.php b/tests/framework/widgets/LinkSorterTest.php
index ae1a75e..baf2221 100644
--- a/tests/framework/widgets/LinkSorterTest.php
+++ b/tests/framework/widgets/LinkSorterTest.php
@@ -34,6 +34,7 @@ class LinkSorterTest extends DatabaseTestCase
     public function testLabelsSimple()
     {
         $dataProvider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => Order::find(),
             'models' => [new Order()],
             'totalCount' => 1,
@@ -58,6 +59,7 @@ class LinkSorterTest extends DatabaseTestCase
     public function testLabelsExplicit()
     {
         $dataProvider = new ActiveDataProvider([
+            'db' => $this->getConnection(),
             'query' => Order::find(),
             'models' => [new Order()],
             'totalCount' => 1,