Simplify the async-related tests

[glunkad]

Implemented a fixture for the "skip async test" function since all test in that file will requires Flask > 2.0
suggested by jonasps and greyli
apiflask/tests/test_async.py
Before

def skip_flask1(app):
    if not hasattr(app, 'ensure_sync'):
        pytest.skip('This test requires Flask 2.0 or higher')

After

@pytest.fixture(autouse=True)
def skip_async_test(app):
    if not hasattr(app, 'ensure_sync'):
        pytest.skip('This test requires Flask 2.0 or higher')

To improve it

• fixes Use pytest autouse fixture in /tests/test_async.py #318

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code docstring.
• Add an entry in CHANGES.md summarizing the change and linking to the issue and your username.
• Add *Version changed* or *Version added* note in any relevant docs and docstring.
• Run pytest and tox, no tests failed.

[greyli]

The fixture with autouse=True will be called automatically for each test function, you don't need to call it.

[jonasps]

I think this looks good now 👍🏻

[glunkad]

@greyli
I am unable to debug the lint error.

[jonasps]

@9gl looks like it might be because you removed the blank line at the end of the file. Not sure.

[greyli]

@9gl It's Ok, I will take care of this later.

For development, you can refer to the contributing guide. The tox command will do the lint check (and the unit tests), and you can fix these issues based on the output. If you skip the local tox check, the GitHub CI will run them as well. You can click the "Details" link on the failing CI check to see the detailed log. For example, now the log shows:

tests/test_async.py:107:1: W293 blank line contains whitespace

It indicated that line 107 in tests/test_async.py contains some whitespace, so you will need to remove them. By the way, don't remove the blank line at the end of the files.

[greyli]

Merged, thanks!

I squashed the commits, so you will need to reset your main branch:

git remote add upstream https://github.com/apiflask/apiflask
git fetch upstream
git reset --hard upstream/main

Next time please use different branches to submit PRs (check out the contributing guide).