前言
“80%的bug集中在20%的模块，越是容易出现bug的模块，bug是越改越多“平常我们做手工测试的时候，比如用100个用例需要执行，其中10个用例失败了，
当开发修复完bug后，我们一般是重点测上次失败的用例。
那么自动化测试也一样，当用例特别多时，为了节省时间，第一次部分用例失败了，修复完之后，可以只测上次失败的用例。
pytest -h
命令行输入pytest -h，找到里面两个命令行参数： --lf 和 --ff
- --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）
--lf 和 --ff
lf是last-failed的缩写，我第一次运行全部测试用例有4个通过passed， 2个失败failed，1个error
E:\YOYO\web_conf_py>pytest
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0
rootdir: E:\YOYO\web_conf_py, inifile:
plugins: metadata-1.7.0, html-1.19.0
collected 7 items
baidu\test_1_baidu.py .. [ 28%]
baidu\test_2.py FF [ 57%]
blog\test_2_blog.py ..E [100%]
=================================== ERRORS ====================================
__________________________ ERROR at setup of test_05 __________________________ file E:\YOYO\web_conf_py\blog\test_2_blog.py, line 11 def test_05(start, open_baidu): E fixture 'open_baidu' not found > available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, metadata, monkeypatch, open_blog, pytestconfig, record_property, record_xml_attribute, record_xml_property, recwarn, start, tmpdir, tmpdir_factory > use 'pytest --fixtures [testpath]' for help on them. E:\YOYO\web_conf_py\blog\test_2_blog.py:11 ================================== FAILURES =================================== ___________________________________ test_06 ___________________________________ start = None, open_baidu = None def test_06(start, open_baidu): print("测试用例test_01") > assert 1==2 E assert 1 == 2 baidu\test_2.py:5: AssertionError ---------------------------- Captured stdout call ----------------------------- 测试用例test_01 ___________________________________ test_07 ___________________________________ start = None, open_baidu = None def test_07(start, open_baidu): print("测试用例test_02") > assert 1==2 E assert 1 == 2 baidu\test_2.py:9: AssertionError ---------------------------- Captured stdout call ----------------------------- 测试用例test_02 ================= 2 failed, 4 passed, 1 error in 0.21 seconds =================如果只想运行其中2个failed的和1error用例，那么可以直接在cmd输入指令
pytest --lf
E:\YOYO\web_conf_py>pytest --lf
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0 rootdir: E:\YOYO\web_conf_py, inifile: plugins: metadata-1.7.0, html-1.19.0 collected 7 items / 4 deselected run-last-failure: rerun previous 3 failures baidu\test_2.py FF [ 66%] blog\test_2_blog.py E [100%] ========================== 2 failed, 4 deselected, 1 error in 0.16 seconds===========================如果想先运行上次失败的，后运行其它通过的用例
pytest --ff
E:\YOYO\web_conf_py>pytest --ff
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0 rootdir: E:\YOYO\web_conf_py, inifile: plugins: metadata-1.7.0, html-1.19.0 collected 7 items run-last-failure: rerun previous 3 failures first baidu\test_2.py FF [ 28%] blog\test_2_blog.py E [ 42%] baidu\test_1_baidu.py .. [ 71%] blog\test_2_blog.py .. [100%] ================= 2 failed, 4 passed, 1 error in 0.14 seconds =================“80%的bug集中在20%的模块，越是容易出现bug的模块，bug是越改越多“平常我们做手工测试的时候，比如用100个用例需要执行，其中10个用例失败了，
当开发修复完bug后，我们一般是重点测上次失败的用例。
那么自动化测试也一样，当用例特别多时，为了节省时间，第一次部分用例失败了，修复完之后，可以只测上次失败的用例。
pytest -h
命令行输入pytest -h，找到里面两个命令行参数： --lf 和 --ff
- --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）
--lf 和 --ff
lf是last-failed的缩写，我第一次运行全部测试用例有4个通过passed， 2个失败failed，1个error
E:\YOYO\web_conf_py>pytest
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0
rootdir: E:\YOYO\web_conf_py, inifile:
plugins: metadata-1.7.0, html-1.19.0
collected 7 items
baidu\test_1_baidu.py .. [ 28%]
baidu\test_2.py FF [ 57%]
blog\test_2_blog.py ..E [100%]
=================================== ERRORS ====================================
__________________________ ERROR at setup of test_05 __________________________ file E:\YOYO\web_conf_py\blog\test_2_blog.py, line 11 def test_05(start, open_baidu): E fixture 'open_baidu' not found > available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, metadata, monkeypatch, open_blog, pytestconfig, record_property, record_xml_attribute, record_xml_property, recwarn, start, tmpdir, tmpdir_factory > use 'pytest --fixtures [testpath]' for help on them. E:\YOYO\web_conf_py\blog\test_2_blog.py:11 ================================== FAILURES =================================== ___________________________________ test_06 ___________________________________ start = None, open_baidu = None def test_06(start, open_baidu): print("测试用例test_01") > assert 1==2 E assert 1 == 2 baidu\test_2.py:5: AssertionError ---------------------------- Captured stdout call ----------------------------- 测试用例test_01 ___________________________________ test_07 ___________________________________ start = None, open_baidu = None def test_07(start, open_baidu): print("测试用例test_02") > assert 1==2 E assert 1 == 2 baidu\test_2.py:9: AssertionError ---------------------------- Captured stdout call ----------------------------- 测试用例test_02 ================= 2 failed, 4 passed, 1 error in 0.21 seconds =================如果只想运行其中2个failed的和1error用例，那么可以直接在cmd输入指令
pytest --lf
E:\YOYO\web_conf_py>pytest --lf
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0 rootdir: E:\YOYO\web_conf_py, inifile: plugins: metadata-1.7.0, html-1.19.0 collected 7 items / 4 deselected run-last-failure: rerun previous 3 failures baidu\test_2.py FF [ 66%] blog\test_2_blog.py E [100%] ========================== 2 failed, 4 deselected, 1 error in 0.16 seconds===========================如果想先运行上次失败的，后运行其它通过的用例
pytest --ff
E:\YOYO\web_conf_py>pytest --ff
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-3.6.3, py-1.5.4, pluggy-0.6.0 rootdir: E:\YOYO\web_conf_py, inifile: plugins: metadata-1.7.0, html-1.19.0 collected 7 items run-last-failure: rerun previous 3 failures first baidu\test_2.py FF [ 28%] blog\test_2_blog.py E [ 42%] baidu\test_1_baidu.py .. [ 71%] blog\test_2_blog.py .. [100%] ================= 2 failed, 4 passed, 1 error in 0.14 seconds =================