使用pytest.raises捕获预期的自定义错误

Question

我是pytest的新手，并试图将一些功能测试脚本转换成pytest很好地运行的脚本。我的模块具有自定义错误类型，我试图使用“with pytest.raises（）as excinfo”方法。这是一个科学/数值软件包，我需要测试某些方法在调用时是否一致，因此我不能深入到低层次的东西。谢谢

Answer 1

什么是阻止您导入特定异常并在您的withpytest.raises声明中使用它？为什么这不起作用？如果你能提供更多关于你面临什么问题的细节，那将会更有帮助。

# your code 

class CustomError(Exception): 
    pass 


def foo(): 
    raise ValueError('everything is broken') 

def bar(): 
    raise CustomError('still broken')  

#############  
# your test 

import pytest 
# import your module, or functions from it, incl. exception class  

def test_fooErrorHandling(): 
    with pytest.raises(ValueError) as excinfo: 
     foo() 
    assert excinfo.value.message == 'everything is broken' 

def test_barSimpleErrorHandling(): 
    # don't care about the specific message 
    with pytest.raises(CustomError): 
     bar() 

def test_barSpecificErrorHandling(): 
    # check the specific error message 
    with pytest.raises(MyErr) as excinfo: 
     bar() 
    assert excinfo.value.message == 'oh no!' 

def test_barWithoutImportingExceptionClass(): 
    # if for some reason you can't import the specific exception class, 
    # catch it as generic and verify it's in the str(excinfo) 
    with pytest.raises(Exception) as excinfo: 
     bar() 
    assert 'MyErr:' in str(excinfo)