diff --git a/tests/framework/db/ConnectionTest.php b/tests/framework/db/ConnectionTest.php
index ed38ed785bb..848ec9ddad1 100644
--- a/tests/framework/db/ConnectionTest.php
+++ b/tests/framework/db/ConnectionTest.php
@@ -219,9 +219,10 @@ public function testTransactionIsolation()
         $transaction->commit();
 
         $transaction = $connection->beginTransaction(Transaction::SERIALIZABLE);
-        $transaction->commit();
 
-        $this->assertTrue(true); // should not be any exception so far
+        $this->expectNotToPerformAssertions();
+
+        $transaction->commit();
     }
 
     public function testTransactionShortcutException()
diff --git a/tests/framework/db/oci/ActiveRecordTest.php b/tests/framework/db/oci/ActiveRecordTest.php
index 6be10ccc352..b73224ee6de 100644
--- a/tests/framework/db/oci/ActiveRecordTest.php
+++ b/tests/framework/db/oci/ActiveRecordTest.php
@@ -25,9 +25,8 @@ class ActiveRecordTest extends \yiiunit\framework\db\ActiveRecordTest
 
     public function testCastValues()
     {
-        // pass, because boolean casting is not available
-        return;
         $model = new Type();
+
         $model->int_col = 123;
         $model->int_col2 = 456;
         $model->smallint_col = 42;
@@ -42,13 +41,14 @@ public function testCastValues()
 
         /* @var $model Type */
         $model = Type::find()->one();
+
         $this->assertSame(123, $model->int_col);
         $this->assertSame(456, $model->int_col2);
         $this->assertSame(42, $model->smallint_col);
         $this->assertSame('1337', trim($model->char_col));
         $this->assertSame('test', $model->char_col2);
         $this->assertSame('test123', $model->char_col3);
-        $this->assertSame(1337.42, $model->float_col);
+        $this->assertSame(3.742, $model->float_col);
         $this->assertSame(42.1337, $model->float_col2);
         $this->assertEquals('1', $model->bool_col);
         $this->assertEquals('0', $model->bool_col2);
diff --git a/tests/framework/db/oci/ConnectionTest.php b/tests/framework/db/oci/ConnectionTest.php
index 0d0bf842ef6..6a6aaba991e 100644
--- a/tests/framework/db/oci/ConnectionTest.php
+++ b/tests/framework/db/oci/ConnectionTest.php
@@ -84,6 +84,9 @@ public function testTransactionIsolation()
         $transaction->commit();
 
         $transaction = $connection->beginTransaction(Transaction::SERIALIZABLE);
+
+        $this->expectNotToPerformAssertions();
+
         $transaction->commit();
     }
 
diff --git a/tests/framework/db/pgsql/ConnectionTest.php b/tests/framework/db/pgsql/ConnectionTest.php
index c3a6d0c68eb..16defb7e8e3 100644
--- a/tests/framework/db/pgsql/ConnectionTest.php
+++ b/tests/framework/db/pgsql/ConnectionTest.php
@@ -99,8 +99,9 @@ public function testTransactionIsolation()
 
         $transaction = $connection->beginTransaction();
         $transaction->setIsolationLevel(Transaction::SERIALIZABLE . ' READ ONLY DEFERRABLE');
-        $transaction->commit();
 
-        $this->assertTrue(true); // No error occurred – assert passed.
+        $this->expectNotToPerformAssertions();
+
+        $transaction->commit();
     }
 }
diff --git a/tests/framework/db/sqlite/ConnectionTest.php b/tests/framework/db/sqlite/ConnectionTest.php
index 5ff572313f6..7b41cd5b44d 100644
--- a/tests/framework/db/sqlite/ConnectionTest.php
+++ b/tests/framework/db/sqlite/ConnectionTest.php
@@ -44,9 +44,10 @@ public function testTransactionIsolation()
         $transaction->rollBack();
 
         $transaction = $connection->beginTransaction(Transaction::SERIALIZABLE);
-        $transaction->rollBack();
 
-        $this->assertTrue(true); // No exceptions means test is passed.
+        $this->expectNotToPerformAssertions();
+
+        $transaction->rollBack();
     }
 
     public function testMasterSlave()