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Pytest或Pytest案例中从夹具返回的参数化列表

pytest-cases pytest python

AlexLordThorsen · 技术社区 · 3 年前

我正在尝试基于随机生成的数据编写一个测试夹具。这些随机生成的数据需要能够接受一个种子,这样我们就可以在两台不同的计算机上同时生成相同的数据。

我在用pytest parse.addoption fixture(我认为这是一个fixture)来增加这种能力。

我的核心问题是,我希望能够参数化一个使用fixture作为参数的随机生成的列表。

from secrets import randbelow

from pytest_cases import parametrize_with_cases, fixture, parametrize

def pytest_addoption(parser):
    parser.addoption("--seed", action="store", default=randbelow(10))

@fixture(scope=session)
def seed(pytestconfig):
    return pytestconfig.getoption("seed")

@fixture(scope=session)
def test_context(seed):
    # In my actual tests these are randomly generated from the seed.
    # each element here is actually a dictionary but I'm showing strings
    # for simplicity of example.
    return ['a', 'test', 'list']


@parametrize(group_item=test_context["group_items"])
def case_group_item(group_item: str): 
    return group_item, "expected_result_goes_here"


@parametrize_with_cases("sql_statement, expected_result", cases='.')
def test_example(
        sql_statement: str,
        expected_result: int) -> None:
    assert False

导致这种结果。

% pytest test.py
========================================================================================================================================================================== test session starts ===========================================================================================================================================================================
platform darwin -- Python 3.8.2, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: /Users/{Home}/tests, configfile: pytest.ini
plugins: datadir-1.3.1, celery-4.4.7, anyio-3.4.0, cases-3.6.11
collected 0 items / 1 error

================================================================================================================================================================================= ERRORS =================================================================================================================================================================================
________________________________________________________________________________________________________________________________________________________________________ ERROR collecting test.py ________________________________________________________________________________________________________________________________________________________________________
test.py:12: in <module>
    ???
E   TypeError: 'function' object is not subscriptable
======================================================================================================================================================================== short test summary info =========================================================================================================================================================================
ERROR test.py - TypeError: 'function' object is not subscriptable
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
============================================================================================================================================================================ 1 error in 0.18s ============================================================================================================================================================================

我想我可以通过制作一个空测试来解决这个问题,该测试将test_context泄露到全局范围,但这感觉真的很脆弱。我正在寻找另一种方法

使用种子夹具生成数据
在生成的列表中为每个元素生成一个测试
不取决于测试的运行顺序。

编辑

以下是一个不适用于直通pytest的示例

import pytest

from pytest_cases import parametrize_with_cases, fixture, parametrize


@fixture
def seed():
    return 1

@fixture
def test_context(seed):
    return [seed, 'a', 'test', 'list']

@pytest.fixture(params=test_context)
def example_fixture(request):
    return request.param

def test_reconciliation(example_fixture) -> None:
    print(example_fixture)
    assert False

pytest test.py
========================================================================================================================================================================== test session starts ===========================================================================================================================================================================
platform darwin -- Python 3.8.2, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: /Users/{HOME}/tests/integration, configfile: pytest.ini
plugins: datadir-1.3.1, celery-4.4.7, anyio-3.4.0, cases-3.6.11
collected 0 items / 1 error

================================================================================================================================================================================= ERRORS =================================================================================================================================================================================
________________________________________________________________________________________________________________________________________________________________________ ERROR collecting test.py ________________________________________________________________________________________________________________________________________________________________________
test.py:14: in <module>
    ???
../../../../../.venvs/data_platform/lib/python3.8/site-packages/_pytest/fixtures.py:1327: in fixture
    fixture_marker = FixtureFunctionMarker(
<attrs generated init _pytest.fixtures.FixtureFunctionMarker>:5: in __init__
    _inst_dict['params'] = __attr_converter_params(params)
../../../../../.venvs/data_platform/lib/python3.8/site-packages/_pytest/fixtures.py:1159: in _params_converter
    return tuple(params) if params is not None else None
E   TypeError: 'function' object is not iterable
======================================================================================================================================================================== short test summary info =========================================================================================================================================================================
ERROR test.py - TypeError: 'function' object is not iterable
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
============================================================================================================================================================================ 1 error in 0.23s ======================================================================================================================================================================

0 回复 | 直到 3 年前

Devang Sanghani 3 年前

我用testfile和conftest.py尝试了你的代码

conftest.py

import pytest
from secrets import randbelow
from pytest_cases import parametrize_with_cases, fixture, parametrize


def pytest_addoption(parser):
    # If you add a breakpoint() here it'll never be hit.
    parser.addoption("--seed", action="store", default=randbelow(1))

@fixture(scope="session")
def seed(pytestconfig):
    # This line throws an exception since seed was never added.
    return pytestconfig.getoption("seed")

myso_test.py

import pytest
from pytest_cases import parametrize_with_cases, fixture, parametrize

@fixture(scope="session")
def test_context(seed):
    # In my actual tests these are randomly generated from the seed.
    # each element here is actually a dictionary but I'm showing strings
    # for simplicity of example.
    return ['a', 'test', 'list']

@parametrize("group_item", [test_context])
def case_group_item(group_item: str): 
    return group_item, "expected_result_goes_here"


@parametrize_with_cases("sql_statement, expected_result", cases='.')
def test_example(
        sql_statement: str,
        expected_result: int) -> None:
    assert True

试运行:

PS C:\Users\AB45365\PycharmProjects\SO> pytest .\myso_test.py -s -v --seed=10 
============================================================== test session starts ==============================================================
platform win32 -- Python 3.9.2, pytest-6.2.5, py-1.10.0, pluggy-1.0.0 -- c:\users\ab45365\appdata\local\programs\python\python39\python.exe       
cachedir: .pytest_cache
rootdir: C:\Users\AB45365\PycharmProjects\SO
plugins: cases-3.6.11, lazy-fixture-0.6.3
collected 1 item

myso_test.py::test_example[group_item-test_context] PASSED

smarie 3 年前

补充 Devang Sanghani's answer :截至pytest 7.1, pytest_addoption 是pytest插件挂钩。因此,对于所有其他插件挂钩,它只能出现在插件文件中或 conftest.py 。

请参阅中的注释 https://docs.pytest.org/en/7.1.x/reference/reference.html#pytest.hookspec.pytest_addoption :

此函数只能在插件或conftest.py中实现由于pytest的发现方式,位于测试根目录中的文件插件。

因此,该问题与 pytest-cases 。

AlexLordThorsen 3 年前

在做了更多的挖掘之后,我遇到了 this documentation around pytest-cases

from secrets import randbelow

import pytest
from pytest_cases import parametrize_with_cases, fixture, parametrize

def pytest_addoption(parser):
    parser.addoption("--seed", action="store", default=randbelow(1))

@fixture(scope="session")
def seed(pytestconfig):
    # return pytestconfig.getoption("seed")
    return 1

@pytest.fixture(scope="session")
def test_context(seed):
    # In my actual tests these are randomly generated from the seed.
    # each element here is actually a dictionary but I'm showing strings
    # for simplicity of example.
    return ['a', 'test', 'list']


@parametrize("group_item", [test_context])
def case_group_item(group_item: str): 
    return group_item, "expected_result_goes_here"


@parametrize_with_cases("sql_statement, expected_result", cases='.')
def test_example(
        sql_statement: str,
        expected_result: int) -> None:
    assert False

不幸的是,这让我遇到了一个新问题。看起来pytest案例当前未调用 pytest_addoption 现在在夹具执行步骤rihgt期间。 I created this ticket 以涵盖这个案例,但这确实有效地解决了我最初的问题,即使它有一个警告。