Pytest编写测试函数
一个规范的测试方法一定带有断言，在使用pytest时，可以直接使用Python自带的assert关键字
Pytest允许在assert关键字添加任意表达式，表达式的值通过bool转换后等于False则表示断言失败，测试用例执行失败；如果等于True则表示断言成功，测试用例执行成功。
重写assertpytest
可以重写assert关键字，它可以截断对原生assert的调用，替换为pytest定义的assert，从而展示更详细的信息和细节。
from collections import namedtuple Task = namedtuple('Task', ['summary','owner','done','id']) # __new__.__defaults__创建默认的Task对象 Task.__new__.__defaults__ = (None, None, False, None) import pytest def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) assert t1 == t2 def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) assert t1_dict == t2_dict
执行结果如下：
E:\Programs\Python\Python_Pytest\TestScripts>pytest test_three.py ======================= test session starts ========================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items test_three.py FF [100%] ===================== FAILURES ================================== _____________________ test_task_equality _______________________________ def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Use -v to get the full diff test_three.py:14: AssertionError -------------------- Captured stdout call ---------------------------------------- Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) ________________ test_dict_equal ______________________________ def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) > assert t1_dict == t2_dict E AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)]) E Omitting 3 identical items, use -vv to show E Differing items: E {'owner': 'okken'} != {'owner': 'okkem'} E Use -v to get the full diff test_three.py:22: AssertionError ------------------------------- Captured stdout call -------------------------------------------- OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)]) OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)]) ================ 2 failed in 0.20 seconds=============================
加上参数-v，执行结果如下：
E:\Programs\Python\Python_Pytest\TestScripts>pytest test_three.py -v ================= test session starts =============================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe cachedir: .pytest_cache rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items test_three.py::test_task_equality FAILED [ 50%] test_three.py::test_dict_equal FAILED [100%] ==================== FAILURES ========================= ____________________ test_task_equality ________________________ def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Full diff: E - Task(summary='sit there', owner='brain', done=False, id=None) E ? ^^^ ^^^ ^^^^ E + Task(summary='do something', owner='okken', done=False, id=None) E ? +++ ^^^ ^^^ ^^^^ test_three.py:14: AssertionError -------------------- Captured stdout call ----------------------------------- Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) ____________________ test_dict_equal ________________________________ def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) > assert t1_dict == t2_dict E AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)]) E Omitting 3 identical items, use -vv to show E Differing items: E {'owner': 'okken'} != {'owner': 'okkem'} E Full diff: E OrderedDict([('summary', 'make sandwich'), E - ('owner', 'okken'), E ? ^... E E ...Full output truncated (5 lines hidden), use '-vv' to show test_three.py:22: AssertionError --------------------------- Captured stdout call -------------------------------- OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)]) OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)]) ================= 2 failed in 0.13 seconds ============================
预期异常
""" 在Task项目的API中，有几个地方可能抛出异常 def add(task): # type:(Task) ->int def get(task_id): # type:(int) ->Task def list_tasks(owner=None): # type:(str|None) ->list of task def count(): # type:(None) ->int def update(task_id, task): # type:(int, Task) ->None def delete(task_id): # type:(int) ->None def delete_all(): # type:() ->None def unique_id(): # type:() ->int def start_tasks_db(db_path, db_type): # type:(str, str) ->None def stop_tasks_db(): # type:() ->None """ import pytest import tasks def test_add_raises(): with pytest.raises(TypeError): tasks.add(task='no a Task object') """ 测试用例中有with pytest.raise(TypeError)生命，意味着无论with结构中的内容是什么 都至少会发生TypeError异常，如果测试通过，说明确实发生了我们预期TypeError，如果抛出的是其他类型的异常 则与我们预期的异常不一致，测试用例执行失败 """ def test_start_tasks_db_raises(): with pytest.raises(ValueError) as excinfo: tasks.start_tasks_db('some/great/path', 'mysql') exception_msg = excinfo.value.args[0] assert exception_msg == "db_type must be a 'tiny' or 'mongo' "
测试函数的标记
from collections import namedtuple import pytest Task = namedtuple('Task', ['summary','owner','done','id']) # __new__.__defaults__创建默认的Task对象 Task.__new__.__defaults__ = (None, None, False, None) @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) assert t1 == t2 @pytest.mark.dict @pytest.mark.smoke def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) assert t1_dict == t2_dict
执行结果如下：
E:\Programs\Python\Python_Pytest\TestScripts>pytest -v -m 'smoke' test_five.py ================ test session starts ===================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe cachedir: .pytest_cache rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items test_five.py::test_task_equality FAILED [ 50%] test_five.py::test_dict_equal FAILED [100%] =================== FAILURES ============================== ______________ test_task_equality _________________________ @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Full diff: E - Task(summary='sit there', owner='brain', done=False, id=None) E ? ^^^ ^^^ ^^^^ E + Task(summary='do something', owner='okken', done=False, id=None) E ? +++ ^^^ ^^^ ^^^^ test_five.py:14: AssertionError ----------------------- Captured stdout call ---------------------------------- Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) ___________________ test_dict_equal ___________________ @pytest.mark.dict @pytest.mark.smoke def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) > assert t1_dict == t2_dict E AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)]) E Omitting 3 identical items, use -vv to show E Differing items: E {'owner': 'okken'} != {'owner': 'okkem'} E Full diff: E OrderedDict([('summary', 'make sandwich'), E - ('owner', 'okken'), E ? ^... E E ...Full output truncated (5 lines hidden), use '-vv' to show test_five.py:24: AssertionError ------------------------ Captured stdout call ------------------------------- OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)]) OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)]) ================ warnings summary ========================= c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo? You can register custom marks to avoi d this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo? You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, -- Docs: https://docs.pytest.org/en/latest/warnings.html ============== 2 failed, 2 warnings in 0.22 seconds =======================
在命令行执行使用了 -m marker_name参数，pytest在执行时会自动寻找被标记为marker_name的测试方法去执行，同时-m还支持and、or、not关键字，如下方式：
E:\Programs\Python\Python_Pytest\TestScripts>pytest -v -m "smoke and not dict" test_five.py =========== test session starts ============================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe cachedir: .pytest_cache rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items / 1 deselected / 1 selected test_five.py::test_task_equality FAILED [100%] =============== FAILURES ================== _______________ test_task_equality ____________________________ @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Full diff: E - Task(summary='sit there', owner='brain', done=False, id=None) E ? ^^^ ^^^ ^^^^ E + Task(summary='do something', owner='okken', done=False, id=None) E ? +++ ^^^ ^^^ ^^^^ test_five.py:14: AssertionError --------------- Captured stdout call ------------------------------ Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) ================ warnings summary ==================== c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo? You can register custom marks to avoi d this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo? You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, -- Docs: https://docs.pytest.org/en/latest/warnings.html ============= 1 failed, 1 deselected, 2 warnings in 0.14 seconds ===========
跳过测试
from collections import namedtuple import pytest Task = namedtuple('Task', ['summary','owner','done','id']) # __new__.__defaults__创建默认的Task对象 Task.__new__.__defaults__ = (None, None, False, None) @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) assert t1 == t2 @pytest.mark.dict @pytest.mark.smoke @pytest.mark.skip(reason="跳过原因你不知道吗？") def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) assert t1_dict == t2_dict
执行结果：
E:\Programs\Python\Python_Pytest\TestScripts>pytest -v test_five.py =============== test session starts =================================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe cachedir: .pytest_cache rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items test_five.py::test_task_equality FAILED [ 50%] test_five.py::test_dict_equal SKIPPED [100%] ============== FAILURES ================================== __________________ test_task_equality _______________________________ @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Full diff: E - Task(summary='sit there', owner='brain', done=False, id=None) E ? ^^^ ^^^ ^^^^ E + Task(summary='do something', owner='okken', done=False, id=None) E ? +++ ^^^ ^^^ ^^^^ test_five.py:14: AssertionError ------------------ Captured stdout call -------------------------------- Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) =========== warnings summary ============================== c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo? You can register custom marks to avoi d this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo? You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, -- Docs: https://docs.pytest.org/en/latest/warnings.html =========== 1 failed, 1 skipped, 2 warnings in 0.21 seconds ================
从测试结果中我们看到，测试用例test_five.py::test_dict_equal SKIPPED 被跳过了，然而跳过原因并没有如期的展示出来，可以使用参数-rs来展示跳过原因，如下方式：
E:\Programs\Python\Python_Pytest\TestScripts>pytest -rs test_five.py ===================== test session starts =========================== platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 rootdir: E:\Programs\Python\Python_Pytest\TestScripts plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3 collected 2 items test_five.py Fs [100%] ============ FAILURES ==================================== __________________________ test_task_equality _______________________ @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) > assert t1 == t2 E AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None) E At index 0 diff: 'sit there' != 'do something' E Use -v to get the full diff test_five.py:14: AssertionError -------------------- Captured stdout call ---------------------------------- Task(summary='sit there', owner='brain', done=False, id=None) Task(summary='do something', owner='okken', done=False, id=None) ========== warnings summary ==================== c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo? You can register custom marks to avoi d this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, c:\python37\lib\site-packages\_pytest\mark\structures.py:324 c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo? You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html PytestUnknownMarkWarning, -- Docs: https://docs.pytest.org/en/latest/warnings.html ============ short test summary info ==================== SKIPPED [1] test_five.py:17: 跳过原因你不知道吗？ ========== 1 failed, 1 skipped, 2 warnings in 0.14 seconds =================
还可以给跳过添加理由，例如当selenium版本是1.0.4的时候跳过
from collections import namedtuple import pytest import selenium Task = namedtuple('Task', ['summary','owner','done','id']) # __new__.__defaults__创建默认的Task对象 Task.__new__.__defaults__ = (None, None, False, None) @pytest.mark.smoke def test_task_equality(): t1 = Task('sit there', 'brain') t2 = Task('do something', 'okken') print(t1) print(t2) assert t1 == t2 @pytest.mark.dict @pytest.mark.smoke @pytest.mark.skipif(selenium.__version__ == '1.0.4', reason="跳过原因你不知道吗？") def test_dict_equal(): t1_dict = Task('make sandwich', 'okken')._asdict() t2_dict = Task('make sandwich', 'okkem')._asdict() print(t1_dict) print(t2_dict) assert t1_dict == t2_dict
运行测试子集
运行单个目录，只需要将目录作为pytest的参数即可 pytest -v test/func --tb=no 1 运行单个测试函数，只需要在文件名后添加::符号和函数名 pytest -v test/func/test_five.py::test_dict_equal 1 运行单个测试类，与运行单个测试函数类似,在文件名后添加::符号和类名 pytest -v test/func/test_five.py::Test_Update 1 运行单个测试类中的测试方法，在文件名后添加::符号和类名然后再跟::符号和函数名 pytest -v test/func/test_five.py::Test_Update::test_dict_equal
