Pytest：請求夾具的嵌套使用

Question

我想獲得一些關於如何使用多層參數化 pytest 裝置運行 pytest 的幫助。

我有一個基於請求的全局夾具，用於選擇要測試的系統的基本實現：

@fixture()
def a_provider():
    yield 'a'


@fixture()
def b_provider():
    yield 'b'


@fixture(params=["a_provider", "b_provider"])
def letter_provider(request):
    yield request.getfixturevalue(request.param)

我現在想針對后端的不同測試用例運行一些額外參數化的測試。

@fixture()
def one(letter_provider):
    yield letter_provider * 1


@fixture()
def two(letter_provider):
    yield letter_provider * 2


@fixture(params=["one", "two"])
def letter_cases(request):
    yield request.getfixturevalue(request.param)

使用這兩層固定裝置，我希望能夠運行由基本實現參數化的兩個測試。

def test_foo(letter_provider):
    """
    Should run once for "a" and once for "b"
    """
    assert letter_provider in {"a", "b"}

以及使用所有附加案例的測試

def test_bar(letter_cases):
    """
    test should be executed 4 times for : a, aa, b, bb
    """
    assert letter_cases in {
        "a", "aa",
        "b", "bb",
    }

目前，我的測試設置失敗：

test setup failed
'letter_provider'

The above exception was the direct cause of the following exception:
letter_provider

During handling of the above exception, another exception occurred:
The requested fixture has no parameter defined for test:
    tests/test_example.py::test_bar[one]

Requested fixture 'letter_provider' defined in:
tests/test_example.py:15

我如何設置我的測試套件來運行這些級別的參數化？

Answer 1

通過將兩個夾具添加為letter_cases依賴項，確保在調用getfixturevalue()時夾具緩存填充one和two夾具值：

@fixture(params=["one", "two"])
def letter_cases(request, one, two):
    yield request.getfixturevalue(request.param)