如何正确地断言在pytest中引发异常?

代码:

# coding=utf-8
import pytest


def whatever():
    return 9/0

def test_whatever():
    try:
        whatever()
    except ZeroDivisionError as exc:
        pytest.fail(exc, pytrace=True)

输出:

================================ test session starts =================================
platform linux2 -- Python 2.7.3 -- py-1.4.20 -- pytest-2.5.2
plugins: django, cov
collected 1 items 

pytest_test.py F

====================================== FAILURES ======================================
___________________________________ test_whatever ____________________________________

    def test_whatever():
        try:
            whatever()
        except ZeroDivisionError as exc:
>           pytest.fail(exc, pytrace=True)
E           Failed: integer division or modulo by zero

pytest_test.py:12: Failed
============================== 1 failed in 1.16 seconds ==============================

如何使pytest打印回溯，所以我将看到在任何函数异常被引发的地方?

当前回答

你的意思是这样的吗?

def test_raises():
    with pytest.raises(Exception) as exc_info:   
        raise Exception('some info')
    # these asserts are identical; you can use either one   
    assert exc_info.value.args[0] == 'some info'
    assert str(exc_info.value) == 'some info'

2014-05-07 10:10:10

其他回答

你的意思是这样的吗?

def test_raises():
    with pytest.raises(Exception) as exc_info:   
        raise Exception('some info')
    # these asserts are identical; you can use either one   
    assert exc_info.value.args[0] == 'some info'
    assert str(exc_info.value) == 'some info'

2014-05-07 10:10:10

您是否尝试删除“pytrace=True”?

pytest.fail(exc, pytrace=True) # before
pytest.fail(exc) # after

你试过用“——fulltrace”运行吗?

2016-02-11 13:57:43

只是添加了另一个“愚蠢”的建议，因为我在现有的答案中没有看到它。本质上，你可以初始化一个错误变量为None，在try/except块中做这件事，然后在那之后检查错误变量的类/值

e = None

try:
    blah()
except Exception as exc:
    e = exc

assert e.__class__ == ValueError # or whatever you expect
assert str(e) == "expected message"

2022-09-12 00:28:35

Pytest在不断地发展，最近有了一个很好的变化，现在可以同时进行测试了

异常类型(严格测试) 错误消息(使用正则表达式进行严格或松散检查)

文档中的两个例子:

with pytest.raises(ValueError, match='must be 0 or None'):
    raise ValueError('value must be 0 or None')

with pytest.raises(ValueError, match=r'must be \d+$'):
    raise ValueError('value must be 42')

我已经在许多项目中使用了这种方法，并且非常喜欢它。

注意: ilya-rusin的这一评论也暗示了上述方法。

2019-06-12 19:55:49

你可以试试

def test_exception():
    with pytest.raises(Exception) as excinfo:   
        function_that_raises_exception()   
    assert str(excinfo.value) == 'some info'

2017-05-24 16:24:50

如何正确地断言在pytest中引发异常?

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