pytest文档53-命令行实时输出错误信息(pytest-instafail)

前言

pytest 运行全部用例的时候，在控制台会先显示用例的运行结果(.或F), 用例全部运行完成后最后把报错信息全部一起抛出到控制台。
这样我们每次都需要等用例运行结束，才知道为什么报错，不方便实时查看报错信息。
pytest-instafail 插件可以在运行用例的时候，需实时查看用例报错内容，这样方便跟踪问题。

--instafail

执行全部用例，报错内容等用例运行完成才显示出来

>pytest
============================= test session starts =============================

collected 11 items

test_s.py ..                                                             [ 18%]
test_t.py ...                                                            [ 45%]
test_x.py .F.F                                                           [ 81%]
test_y.py ..                                                             [100%]

================================== FAILURES ===================================
___________________________________ test_02 ___________________________________

    def test_02():
        a = "hello"
        b = "hello world"
>       assert a == b
E       AssertionError: assert 'hello' == 'hello world'
E         - hello
E         + hello world

test_x.py:12: AssertionError
___________________________________ test_04 ___________________________________

    def test_04():
        a = "hello"
        b = "hello world"
>       assert a not in b
E       AssertionError: assert 'hello' not in 'hello world'
E         'hello' is contained here:
E           hello world

test_x.py:24: AssertionError
===================== 2 failed, 9 passed in 1.32 seconds ======================

当用例很多的时候，不方便我们查看具体哪个报错对应哪条用例，加上--instafail参数，方便实时查看报错内容

>pytest --instafail
============================= test session starts =============================

collected 11 items

test_s.py ..                                                             [ 18%]
test_t.py ...                                                            [ 45%]
test_x.py .F

___________________________________ test_02 ___________________________________

    def test_02():
        a = "hello"
        b = "hello world"
>       assert a == b
E       AssertionError: assert 'hello' == 'hello world'
E         - hello
E         + hello world

test_x.py:12: AssertionError

test_x.py .F

___________________________________ test_04 ___________________________________

    def test_04():
        a = "hello"
        b = "hello world"
>       assert a not in b
E       AssertionError: assert 'hello' not in 'hello world'
E         'hello' is contained here:
E           hello world

test_x.py:24: AssertionError

test_y.py ..                                                             [100%]

===================== 2 failed, 9 passed in 1.37 seconds ======================

结合--tb=line参数，看起来更直观

>pytest --instafail --tb=line
============================= test session starts =============================
collected 11 items

test_s.py ..                                                             [ 18%]
test_t.py ...                                                            [ 45%]
test_x.py .F

D:	est_x.py:12: AssertionError: assert 'hello' == 'hello world'

test_x.py .F

D:	est_x.py:24: AssertionError: assert 'hello' not in 'hello world'

test_y.py ..                                                             [100%]

===================== 2 failed, 9 passed in 1.30 seconds ======================