pytest 核心功能-重新運行失敗的測試并在測試運行之間保持狀態(tài)

用法

該插件提供了兩個命令行選項來重新運行上次 pytest 調(diào)用的失?。?/p>

• ?--lf?, ?--last-failed? - 只重新運行失敗。
• ?--ff?, ?--failed-first? - 先運行失敗，然后運行其余測試。

對于清理（通常不需要）， ?--cache-clear? 選項允許在測試運行之前刪除所有跨會話緩存內(nèi)容。

其他插件可以訪問 ?config.cache? 對象以在 pytest 調(diào)用之間設(shè)置/獲取 ?json可編碼值。

只重新運行失敗或先運行失敗

首先，我們創(chuàng)建50個測試調(diào)用，其中只有2個失敗:

# content of test_50.py
import pytest


@pytest.mark.parametrize("i", range(50))
def test_num(i):
    if i in (17, 25):
        pytest.fail("bad luck")

如果你第一次運行這個，你會看到兩個失敗:

$ pytest -q
.................F.......F........................                   [100%]
================================= FAILURES =================================
_______________________________ test_num[17] _______________________________

i = 17

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
_______________________________ test_num[25] _______________________________

i = 25

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
========================= short test summary info ==========================
FAILED test_50.py::test_num[17] - Failed: bad luck
FAILED test_50.py::test_num[25] - Failed: bad luck
2 failed, 48 passed in 0.12s

然后如果你用 ?--lf? 運行它：

$ pytest --lf
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-7.x.y, pluggy-1.x.y
rootdir: /home/sweet/project
collected 2 items
run-last-failure: rerun previous 2 failures

test_50.py FF                                                        [100%]

================================= FAILURES =================================
_______________________________ test_num[17] _______________________________

i = 17

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
_______________________________ test_num[25] _______________________________

i = 25

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
========================= short test summary info ==========================
FAILED test_50.py::test_num[17] - Failed: bad luck
FAILED test_50.py::test_num[25] - Failed: bad luck
============================ 2 failed in 0.12s =============================

您只運行了上次運行的兩個失敗的測試，而 48 個通過的測試還沒有運行。

現(xiàn)在，如果您使用 ?--ff? 選項運行，所有測試都將運行，但之前的第一個失敗將首先執(zhí)行：

$ pytest --ff
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-7.x.y, pluggy-1.x.y
rootdir: /home/sweet/project
collected 50 items
run-last-failure: rerun previous 2 failures first

test_50.py FF................................................        [100%]

================================= FAILURES =================================
_______________________________ test_num[17] _______________________________

i = 17

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
_______________________________ test_num[25] _______________________________

i = 25

    @pytest.mark.parametrize("i", range(50))
    def test_num(i):
        if i in (17, 25):
>           pytest.fail("bad luck")
E           Failed: bad luck

test_50.py:7: Failed
========================= short test summary info ==========================
FAILED test_50.py::test_num[17] - Failed: bad luck
FAILED test_50.py::test_num[25] - Failed: bad luck
======================= 2 failed, 48 passed in 0.12s =======================

新的 ?--nf?，?--new-first? 選項：首先運行新測試，然后是其余測試，在這兩種情況下，測試也按文件修改時間排序，最近的文件首先出現(xiàn)。

上次運行中沒有測試失敗時的行為

如果在上次運行中沒有測試失敗，或者沒有找到緩存的 lastfailed 數(shù)據(jù)，則可以使用 --last-failed-no-failures 選項將 pytest 配置為運行所有測試或不運行測試，該選項采用以下選項之一 ：

pytest --last-failed --last-failed-no-failures all    # run all tests (default behavior)
pytest --last-failed --last-failed-no-failures none   # run no tests and exit

新的 config.cache 對象

插件或 ?conftest.py? 支持代碼可以使用 pytest 配置對象獲取緩存值。 這是一個基本示例插件，它實現(xiàn)了一個在 pytest 調(diào)用中重用先前創(chuàng)建的狀態(tài)的?fixture?：

# content of test_caching.py
import pytest
import time


def expensive_computation():
    print("running expensive computation...")


@pytest.fixture
def mydata(request):
    val = request.config.cache.get("example/value", None)
    if val is None:
        expensive_computation()
        val = 42
        request.config.cache.set("example/value", val)
    return val


def test_function(mydata):
    assert mydata == 23

如果你是第一次運行這個命令，你可以看到 ?print語句：

$ pytest -q
F                                                                    [100%]
================================= FAILURES =================================
______________________________ test_function _______________________________

mydata = 42

    def test_function(mydata):
>       assert mydata == 23
E       assert 42 == 23

test_caching.py:20: AssertionError
-------------------------- Captured stdout setup ---------------------------
running expensive computation...
========================= short test summary info ==========================
FAILED test_caching.py::test_function - assert 42 == 23
1 failed in 0.12s

如果您再次運行它，將從緩存中檢索該值，并且不會打印任何內(nèi)容：

$ pytest -q
F                                                                    [100%]
================================= FAILURES =================================
______________________________ test_function _______________________________

mydata = 42

    def test_function(mydata):
>       assert mydata == 23
E       assert 42 == 23

test_caching.py:20: AssertionError
========================= short test summary info ==========================
FAILED test_caching.py::test_function - assert 42 == 23
1 failed in 0.12s

檢查緩存內(nèi)容

您始終可以使用 ?--cache-show? 命令行選項查看緩存的內(nèi)容：

$ pytest --cache-show
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-7.x.y, pluggy-1.x.y
rootdir: /home/sweet/project
cachedir: /home/sweet/project/.pytest_cache
--------------------------- cache values for '*' ---------------------------
cache/lastfailed contains:
  {'test_caching.py::test_function': True}
cache/nodeids contains:
  ['test_caching.py::test_function']
cache/stepwise contains:
  []
example/value contains:
  42

========================== no tests ran in 0.12s ===========================

?--cache-show? 采用可選參數(shù)來指定用于過濾的全局模式：

$ pytest --cache-show example/*
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-7.x.y, pluggy-1.x.y
rootdir: /home/sweet/project
cachedir: /home/sweet/project/.pytest_cache
----------------------- cache values for 'example/*' -----------------------
example/value contains:
  42

========================== no tests ran in 0.12s ===========================

清除緩存內(nèi)容

您可以通過添加 ?--cache-clear? 選項來指示 pytest 清除所有緩存文件和值，如下所示：

pytest --cache-clear

對于來自持續(xù)集成服務(wù)器的調(diào)用，建議這樣做，因為隔離和正確性比速度更重要。

Stepwise

作為 ?--lf -x? 的替代方案，特別是對于您預(yù)計大部分測試套件將失敗的情況，?--sw?, ?--stepwise? 允許您一次修復(fù)一個。 測試套件將一直運行到第一次失敗，然后停止。 在下一次調(diào)用時，測試將從上一個失敗的測試繼續(xù)，然后運行直到下一個失敗的測試。 您可以使用 ?--stepwise-skip? 選項忽略一個失敗的測試并在第二個失敗的測試上停止測試執(zhí)行。 如果您陷入失敗的測試并且只想在以后忽略它，這很有用。 提供 ?--stepwise-skip? 也將隱式啟用 ?--stepwise?