pytest文檔42-fixture參數化params

前言

參數化是自動化測試里面必須掌握的一個知識點，用過 unittest 框架的小伙伴都知道使用 ddt 來實現測試用例的參數化。
pytest 測試用例里面對應的參數可以用 parametrize 實現，隨着用例的增多，我們的需求也會越來越多，那么如何在 fixture 中使用參數呢？

fixture 源碼

先看下 fixture 源碼，有這幾個參數：scope，params，autouse，ids，name。

def fixture(scope="function", params=None, autouse=False, ids=None, name=None):
    """Decorator to mark a fixture factory function.

    This decorator can be used, with or without parameters, to define a
    fixture function.

    The name of the fixture function can later be referenced to cause its
    invocation ahead of running tests: test
    modules or classes can use the ``pytest.mark.usefixtures(fixturename)``
    marker.

    Test functions can directly use fixture names as input
    arguments in which case the fixture instance returned from the fixture
    function will be injected.

    Fixtures can provide their values to test functions using ``return`` or ``yield``
    statements. When using ``yield`` the code block after the ``yield`` statement is executed
    as teardown code regardless of the test outcome, and must yield exactly once.

    :arg scope: the scope for which this fixture is shared, one of
                ``"function"`` (default), ``"class"``, ``"module"``,
                ``"package"`` or ``"session"``.

                ``"package"`` is considered **experimental** at this time.

    :arg params: an optional list of parameters which will cause multiple
                invocations of the fixture function and all of the tests
                using it.
                The current parameter is available in ``request.param``.

    :arg autouse: if True, the fixture func is activated for all tests that
                can see it.  If False (the default) then an explicit
                reference is needed to activate the fixture.

    :arg ids: list of string ids each corresponding to the params
                so that they are part of the test id. If no ids are provided
                they will be generated automatically from the params.

    :arg name: the name of the fixture. This defaults to the name of the
                decorated function. If a fixture is used in the same module in
                which it is defined, the function name of the fixture will be
                shadowed by the function arg that requests the fixture; one way
                to resolve this is to name the decorated function
                ``fixture_<fixturename>`` and then use
                ``@pytest.fixture(name='<fixturename>')``.
    """
    if callable(scope) and params is None and autouse is False:
        # direct decoration
        return FixtureFunctionMarker("function", params, autouse, name=name)(scope)
    if params is not None and not isinstance(params, (list, tuple)):
        params = list(params)
    return FixtureFunctionMarker(scope, params, autouse, ids=ids, name=name)

重點看 params 參數：一個可選的參數列表，它將導致多次調用fixture函數和使用它的所有測試
獲取當前參數可以使用 request.param

    :arg params: an optional list of parameters which will cause multiple
                invocations of the fixture function and all of the tests
                using it.
                The current parameter is available in ``request.param``.

fixture 之 params 使用示例

request 是pytest的內置 fixture ，主要用於傳遞參數

# test_fixture_params.py
import pytest
# 作者-上海悠悠 QQ交流群:717225969
# blog地址 https://www.cnblogs.com/yoyoketang/


# 測試數據，存放在list
user_data = ["user1", "user2"]

@pytest.fixture(scope="function", params=user_data)
def users(request):
    '''注冊用戶參數化'''
    return request.param


def test_register(users):
    print("注冊用戶：%s"%users)

if __name__ == '__main__':
    pytest.main(["-s", "test_fixture_params"])

運行結果

>pytest test_fixture_params.py -s
============================= test session starts =============================
platform win32 -- Python 3.6.0, pytest-4.5.0, py-1.5.4, pluggy-0.13.1
rootdir: D:\soft\demo
plugins: allure-pytest-2.8.6
collected 2 items

test_fixture_params.py 注冊用戶：user1
.注冊用戶：user2
.

========================== 2 passed in 0.02 seconds ===========================

前置與后置

如果每次注冊用戶之前，需先在前置操作里面清理用戶注冊表的數據，可以執行SQL,傳不同用戶的參數

# test_fixture_params.py
import pytest
# 作者-上海悠悠 QQ交流群:717225969
# blog地址 https://www.cnblogs.com/yoyoketang/

def delete_sql(user):
    '''這里執行SQL'''
    sql = "delete from auth_user WHERE username = '%s';"%user
    print("執行的sql:%s"%sql)
    # 調用執行SQL的封裝函數


# 測試數據，存放在list
user_data = ["user1", "user2"]

@pytest.fixture(scope="function", params=user_data)
def users(request):
    '''注冊用戶參數化'''

    # 前置操作
    delete_sql(request.param)

    yield request.param

    # # 后置操作
    # delete_sql(request.param)


def test_register(users):
    print("注冊用戶：%s"%users)

if __name__ == '__main__':
    pytest.main(["-s", "test_fixture_params.py"])

運行結果

collected 2 items

test_fixture_params.py 執行的sql:delete from auth_user WHERE username = 'user1';
注冊用戶：user1
.執行的sql:delete from auth_user WHERE username = 'user2';
注冊用戶：user2
.

========================== 2 passed in 0.06 seconds ===========================

后置操作可以寫到 yield 后面，參考上面的格式。