参数化固定装置不适用于 Pytest

Question

我已经在 fixtures (@pytest.fixture(params=params)) 上使用 params 到运行具有多个测试用例的相同测试。在这种情况下，我想我做的完全一样，但这次夹具没有 return 任何东西。奇怪的是，测试运行是我传递给函数的参数数量的两倍。

所以，我的示例代码：

def double(n):
    return 2 * n


TEST_CASES_DOUBLE = [
    #(input, expected)
    (1, 2),
    (2, 4),
    (3, 6),
]

# Fixtures


@pytest.fixture(params=TEST_CASES_DOUBLE)
def params_function_double(request):
    request.param


# Tests


def test_double(params_function_double):
    param, expected = params_function_double
    result = double(param)
    assert result == expected

我收到错误：

======================================================================================= FAILURES ========================================================================================
_________________________________________________________________________ test_double[params_function_double0] __________________________________________________________________________

params_function_double = None

    def test_double(params_function_double):
>       param, expected = params_function_double
E       TypeError: cannot unpack non-iterable NoneType object

test.py:56: TypeError
_________________________________________________________________________ test_double[params_function_double1] __________________________________________________________________________

params_function_double = None

    def test_double(params_function_double):
>       param, expected = params_function_double
E       TypeError: cannot unpack non-iterable NoneType object

test.py:56: TypeError
_________________________________________________________________________ test_double[params_function_double2] __________________________________________________________________________

params_function_double = None

    def test_double(params_function_double):
>       param, expected = params_function_double
E       TypeError: cannot unpack non-iterable NoneType object

test.py:56: TypeError
================================================================================ short test summary info ================================================================================
FAILED test.py::test_double[params_function_double0] - TypeError: cannot unpack non-iterable NoneType object
FAILED test.py::test_double[params_function_double1] - TypeError: cannot unpack non-iterable NoneType object
FAILED test.py::test_double[params_function_double2] - TypeError: cannot unpack non-iterable NoneType object

Answer 1

主要问题是您的 params_function_double 没有返回任何内容，因此您会收到 NoneType 错误。

您可能正在寻找的不是 fixture 装饰器，而是 pytest.mark.parametrize 装饰器（参见 this page）。这是测试实现的样子

def double(n):
    return 2 * n

# Tests
@pytest.mark.parametrize(
    "input_, expected",
    [(1, 2), (2, 4), (3, 6)]
)
def test_double(input_, expected):
    result = double(input_)
    assert result == expected

参数化固定装置不适用于 Pytest

Parameterizing fixtures not working on Pytest

python

pytest

fixtures