pytest xfail参数详解

源码使用说明
```
    def xfail(self,condition=None, reason=None, raises=None, run=True, strict=False):
        """mark the the test function as an expected failure if eval(self,condition)
        has a True value.

        Optionally specify a reason for better reporting and run=False if
        you don't even want to execute the test function.

        See http://doc.pytest.org/en/latest/skipping.html
        """
```

1. 直接使用@pytest.mark.xfail

@pytest.mark.xfail
def test_01():
    assert 1 == 1


@pytest.mark.xfail
def test_02():
    assert 1 == 2

运行结果为

 使用xfail标记用例预期失败，如果用例运行成功则显示Xpassed，失败则显示xfailed。xfail标记并不会影响用例的运行

2.strict参数 ：设置strict=True以确保XPASS时，测试的记录为失败

同样使用该代码

@pytest.mark.xfail(strict=True)
def test_01():
    assert 1 == 1


@pytest.mark.xfail
def test_02():
    assert 1 == 2

运行结果

 xpass运行的结果现在显示为failed

3，结合skipif 条件，条件为Ture运行xfail

@pytest.mark.xfail(1 >= 5, reason='test')
def test_01():
    assert 1 == 1

@pytest.mark.xfail(1 >= 5, reason='test')
def test_02():
    assert 1 == 5


@pytest.mark.xfail(1 <= 5, reason='test')
def test_03():
    assert 1 == 1


@pytest.mark.xfail(1 <= 5, reason='test')
def test_04():
    assert 1 == 2

运行结果

 用例01、02，因为条件为false所以不运行xfail，结果显示为pass、fail

03、04条件为true，运行xfail，结果显示为xpass、xfail

4raises参数

具体的说明测试失败的原因。可以在raises参数中指定单个异常或异常组，如果测试失败且没有提到指定的异常，那么测试将被报告为常规失败raises

@pytest.mark.xfail(raises=AssertionError)
def test_01():
    assert 1 == 2


@pytest.mark.xfail(raises=ValueError)
def test_02():
    if isinstance('1234', int) is not True:
        raise TypeError("传入参数非整数")

运行结果：

 01测试用例，异常为指定异常，xfail运行，结果显示xfailed

02测试用例，异常为非指定异常，xfail不运行，结果显示failed