前言

pytest 运行完用例之后会生成一个 .pytest_cache 的缓存文件夹，用于记录用例的ids和上一次失败的用例。
方便我们在运行用例的时候加上–lf 和 –ff 参数，快速运行上一次失败的用例。
–lf, –last-failed 只重新运行上次运行失败的用例（或如果没有失败的话会全部跑）
–ff, –failed-first 运行所有测试，但首先运行上次运行失败的测试（这可能会重新测试，从而导致重复的fixture setup/teardown）

cache

pytest -h 查看命令行参数，关于 cache 参数的使用方式

> pytest -h

--lf, --last-failed   rerun only the tests that failed at the last 
                      run (or all if none failed)
--ff, --failed-first  run all tests, but run the last failures first.
                      This may re-order tests and thus lead to repeated fixture                                   											setup/teardown.
--nf, --new-first     run tests from new files first, then the rest of the tests sorted by 												file mtime
--cache-show=[CACHESHOW]
                      show cache contents, don't perform collection or tests. Optional      											argument: glob(default: '*').
--cache-clear         remove all cache contents at start of test run.

参数说明：

–lf 也可以使用 --last-failed 仅运行上一次失败的用例
–ff 也可以使用 --failed-first 运行全部的用例，但是上一次失败的用例先运行
–nf 也可以使用 --new-first 根据文件插件的时间，新的测试用例会先运行
–cache-show=[CACHESHOW] 显示.pytest_cache文件内容，不会收集用例也不会测试用例，选项参数: glob (默认: ‘*’)
–cache-clear 测试之前先清空.pytest_cache文件

–cache-show

案例

def test_01():
    a = "hello"
    b = "hello"
    assert a == b


def test_02():
    a = "hello"
    b = "hello world"
    assert a == b


def test_03():
    a = "hello"
    b = "hello world"
    assert a in b


def test_04():
    a = "hello"
    b = "hello world"
    assert a not in b

命令行输入运行完成后，会有2个用例失败，2个用例成功

collecting ... 
 case/test_1.py ✓                                                                                                                                                                                         25% ██▌       

 case/test_1.py ⨯✓                                                                                                                                                                                        75% ███████▌  

 case/test_1.py ⨯                                                                                                                                                                                        100% ██████████

运行完成后，会在当前的目录生成一个 .pytest_cache 的缓存文件夹,层级结构如下

pytest运行_python缓存机制

lastfailed 文件记录上一次运行失败的用例

{
  "test_x.py::test_02": true,
  "test_x.py::test_04": true
}

nodeids 文件记录所有用例的节点

[
  "test_x.py::test_01",
  "test_x.py::test_02",
  "test_x.py::test_03",
  "test_x.py::test_04"
]

于是可以通过 pytest –cache-show 命令查看cache目录

(pytest_env) ➜  apiAutomatic pytest --cache-show
Test session starts (platform: darwin, Python 3.7.6, pytest 6.2.1, pytest-sugar 0.9.4)
rootdir: /Users/jkc/PycharmProjects/apiAutomatic, configfile: pytest.ini
plugins: assume-2.4.2, sugar-0.9.4, rerunfailures-9.1.1, base-url-1.4.2, html-3.1.1, metadata-1.11.0, ordering-0.6, cov-2.10.1, repeat-0.9.1, xdist-2.2.0, forked-1.3.0, allure-pytest-2.8.29
cachedir: /Users/jkc/PycharmProjects/apiAutomatic/.pytest_cache
------------------------------------------------------------------------------------------------- cache values for '*' -------------------------------------------------------------------------------------------------
cache/lastfailed contains:
  {'case/test_1.py::test_02': True, 'case/test_1.py::test_04': True}
cache/nodeids contains:
  ['case/test_1.py::test_01',
   'case/test_1.py::test_02',
   'case/test_1.py::test_03',
   'case/test_1.py::test_04']
cache/stepwise contains:
  []
Results (0.02s):