如何在pytest中捕获异常后打印消息

Assume this sample code:

假设此示例代码:

def test_foo():
    dict = load_dict()
    try:
        value = dict[foo][bar]
    except KeyError:
        print('missing foo or bar')

If it raises KeyError because either foo or bar doesn't exist, the test will not fail because the exception is captured. If I add a raise SystemExit(1), it fails, prints the message and shows all the traceback.

如果它引发KeyError,因为foo或bar不存在,测试将不会失败,因为捕获了异常。如果我添加一个提升SystemExit(1),它会失败,打印消息并显示所有回溯。

My question is, how can I tell pytest that if a KeyError occurred it means the test failed, so that I don't need to raise a SystemExit?

我的问题是,如何告诉pytest如果发生KeyError则意味着测试失败,这样我就不需要提出SystemExit了?

2 个解决方案

#1

There is a function pytest.fail that explicitly fails the test:

有一个函数pytest.fail明确地失败了测试:

import pytest

def test_foo():
    d1 = {'foo': 'bar'}
    try:
        value = d1['baz']
    except KeyError as err:
        pytest.fail('this was unexpected: {}'.format(err))

However, the idiomatic way would be using the pytest.raises context manager that verifies the exception is raised, capturing it for analysis with some convenient utilities:

然而,惯用的方法是使用pytest.raises上下文管理器来验证引发的异常,使用一些方便的实用程序捕获它以进行分析:

import pytest

def test_foo():
    d1 = {'foo': 'bar'}
    with pytest.raises(KeyError) as excinfo:
        value = d1['baz']
    assert excinfo.type == KeyError
    assert excinfo.match('baz')

Check out the docs for more examples. If you are familiar with unittest, pytest.raises is the pendant to unittest.TestCase.assertRaises, while pytest.fail is the pendant to unittest.TestCase.fail.

查看文档以获取更多示例。如果您熟悉unittest,pytest.raises是unittest.TestCase.assertRaises的吊坠,而pytest.fail是unittest.TestCase.fail的吊坠。

#2

You can use the with pytest.raises constructor:

您可以使用with pytest.raises构造函数:

def test_connection_fails(self,):
    with pytest.raises(KeyError) as excinfo:
        buckets = list_all_buckets()

Then you can raise an error without using sys.exit

然后,您可以在不使用sys.exit的情况下引发错误

#1