Python 在未加载的功能级别上表现夹具

Question

这与 this question 有点相关，但我在下面的这个最小示例中还有一些其他问题。

为了功能测试，我准备了一个固定装置，它备份了一个文件，该文件将在测试期间进行修改运行（例如，附加了一行）。经过测试运行这个fixture恢复了原文件

项目文件：

└───features
    │   environment.py
    │   modify_file.feature
    │
    └───steps
            file_ops.py

#!/usr/bin/env python
# FILE: features/environment.py

import logging
from behave import fixture
from behave.runner import Context

logger = logging.getLogger(__name__)


@fixture
def backup_file(context: Context):
    """
    A file will be modified during the feature test.
    This fixture shall backup the file before the feature test
    and restore the backup after the test.
    """
    file = Path.home() / "important.txt"
    backup_suffix = ".backup"
    file.touch()
    file.replace(file.with_suffix(backup_suffix))
    logger.info("File backed up")
    yield
    file.with_suffix(backup_suffix).replace(file)
    logger.info("File restored")

# FILE: features/modify_file.feature

@fixture.backup.file
Feature: Modify file

        @wip
        Scenario: Append a line to a file
                Given the file exists
                When I append a line to the file
                Then the line appears at the end of the file

#!/usr/bin/env python
# File features/steps/file_ops.py

from pathlib import Path
from behave import given
from behave import when
from behave import then
from behave.runner import Context
import logging

logger = logging.getLogger(__name__)
file = Path.home() / "important.txt"


@given("the file exists")
def step_impl(context: Context):
    logger.info(f"Touching file")
    file.touch()


@when("I append a line to the file")
def step_impl(context: Context):
    logger.info(f"Appending a line to file")
    context.appended = "Test line appended\n"
    with open(file, mode="a") as f:
        f.write(context.appended)


@then("the line appears at the end of the file")
def step_impl(context: Context):
    logger.info(f"Checking if line was appended")
    with open(file, mode="r") as f:
        for line in f:
            pass
        logger.info(f"Last line is '{line.strip()}'")
        assert line == context.appended

我想在所有场景运行之前在功能级别应用fixture。待所有场景运行后恢复文件。然而，事实显然并非如此。

当我运行 behave -w（无日志捕获，仅 wip 标签）时，我没有看到正在输出的夹具的任何日志行以及每个运行我看到文件中附加了另一行。这意味着文件没有被备份和恢复。即使在我将夹具向下移动到场景级别 modify_file.feature 文件中，也不会应用夹具。

你能帮我理解这是怎么回事吗？我也很好奇为什么夹具标签使用点符号 (@fixture.backup.file) 而不是 (fixture.backup_file)，因为这与实际函数名称相似。 behave documentation.

中没有对此的解释

Answer 1

下面是不用 @fixture 的方法，只需使用 before_tag 钩子即可：

#!/usr/bin/env python
# FILE: features/environment.py

import logging
from behave.runner import Context
from behave.model import Tag
from pathlib import Path

logger = logging.getLogger(__name__)


def rename_file(origin: Path, target: Path) -> tuple[Path, Path]:
    """
    Will rename the `origin` to `target`, replaces existing `target`
    """
    origin.touch()
    backup = origin.replace(target)
    logger.info(f"File {str(origin)} renamed to {str(target)}")
    return origin, backup


def before_tag(context: Context, tag: Tag):
    if tag == "backup.file.important.txt":
        file = Path.home() / "important.txt"
        backup = file.with_suffix(".backup")
        context.file, context.backup_file = rename_file(file, backup)
        context.add_cleanup(rename_file, context.backup_file, context.file)

#!/usr/bin/env python
# File features/steps/file_ops.py

from pathlib import Path
from behave import given
from behave import when
from behave import then
from behave.runner import Context
import logging

logger = logging.getLogger(__name__)


@given("the file exists")
def step_impl(context: Context):
    logger.info(f"Touching file")
    context.file.touch()


@when("I append a line to the file")
def step_impl(context: Context):
    logger.info(f"Appending a line to file")
    context.appended = "Test line appended\n"
    with open(context.file, mode="a") as f:
        f.write(context.appended)


@then("the line appears at the end of the file")
def step_impl(context: Context):
    logger.info(f"Checking if line was appended")
    with open(context.file, mode="r") as f:
        for n, line in enumerate(f, start=1):
            logger.info(f"Line {n} is {line}")
        logger.info(f"Last line is '{line.strip()}'")
        assert line == context.appended

但是使用 behave 文档中 Realistic example 中描述的夹具和夹具注册表是更好的选择，因为您以后可能会得到更多 setup-cleanup 对。

Python 在未加载的功能级别上表现夹具

Python behave fixture on feature level not loaded

python

python-behave