如何在单元测试时模拟db失败

Question

我使用phpUnit并通过扩展PHPUnit_Extensions_Database_TestCase来编写涉及数据库的测试。 如何模拟数据库故障以测试我的错误检查？我应该测试什么样的失败发生，除了数据库被关闭？

我发现this Ruby on Rails question，但发现它与phpUnit无关。

Answer 1

我把代码块分开，然后use Mocks/Stubs in PHPUnit去控制从数据库调用返回来包含错误，所以我的主代码会处理这个错误。我不使用实际的数据库，而是测试执行交互的代码，以通过例外或您的代码期望的方法来处理数据库错误。

为了模拟从您的代码与模拟相同的回报，你会做以下几点：使用

$stub = $this->getMock('YourDBClass'); 

// Configure the stub to return an error when the RunQuery method is called 
$stub->expects($this->any()) 
    ->method('RunQuery') 
    ->will($this->throwException(new SpecificException)); 

您可以测试的@expectsException

/** 
* @expectedException SpecificException 
*/ 
public function testDBError() 
{ 
    $stub = $this->getMock('YourDBClass'); 

    // Configure the stub to return an error when the RunQuery method is called 
    $stub->expects($this->any()) 
     ->method('RunQuery') 
     ->will($this->throwException(new SpecificException)); 

    $stub->RunQuery(); 
} 

或使用setExpectedException

public function testDBError() 
{ 
    $stub = $this->getMock('YourDBClass'); 

    // Configure the stub to return an error when the RunQuery method is called 
    $stub->expects($this->any()) 
     ->method('RunQuery') 
     ->will($this->throwException(new SpecificException)); 

    $this->setExpectedException('SpecificException'); 
    $stub->RunQuery(); 
} 

然后您将以相同的方式测试已知回报

public function testDBQueryReturns1() 
{ 
    $stub = $this->getMock('YourDBClass'); 

    // Configure the stub to return an error when the RunQuery method is called 
    $stub->expects($this->any()) 
     ->method('RunQuery') 
     ->will($this->returnValue(1)); 

    $this->assertEquals(1, $stub->RunQuery(), 'Testing for the proper return value'); 
}