AssertionError raised by test_file_response method of ASGITest class.

[Yash Saini]

On running:
python runtests.py asgi
The following assertion is raised in tests\asgi\tests.py in ASGITest.test_file_response method:

    AssertionError: Items in the first set but not the second:
    (b'Content-Type', b'text/x-python')
    Items in the second set but not the first:
    (b'Content-Type', b'text/plain')

[Mariusz Felisiak]

Content-type depends on a platform. Jenkins doesn't report this issue on Windows and Linux. What platform and Python version are you using?

[Yash Saini]

I am using Windows 10 and python 3.7.7.

[Carlton Gibson]

The failure doesn't reproduce for me on Windows with Python 3.7 or 3.8.

[Addison Snelling]

I think the test is incorrect in expecting text/plain instead of text/x-python as the content type for a Python file

test_file_response in tests/asgi/tests.py fails for me as well.

(.venv) PS D:\source\django\tests> py runtests.py asgi.tests
...
======================================================================
FAIL: test_file_response (asgi.tests.ASGITest)
Makes sure that FileResponse works over ASGI.
----------------------------------------------------------------------
...
AssertionError: Items in the first set but not the second:
(b'Content-Type', b'text/x-python')
Items in the second set but not the first:
(b'Content-Type', b'text/plain')

My environment (Windows 10 Pro Build 20211):

>>> sys.platform
'win32'
>>> sys.getwindowsversion()
sys.getwindowsversion(major=10, minor=0, build=20211, platform=2, service_pack='')
>>> sys.version
'3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)]'

The set_headers method of django.http.FileResponse queries the content type of the file on ​line 467:

content_type, encoding = mimetypes.guess_type(filename)

On my machine, the above line sets content_type to text/x-python, but ​line 79 in the test file expects text/plain on Windows platforms:

self.assertEqual(
    set(response_start['headers']),
    {
        (b'Content-Length', str(len(test_file_contents)).encode('ascii')),
        (b'Content-Type', b'text/plain' if sys.platform == 'win32' else b'text/x-python'),  # line 79
        (b'Content-Disposition', b'inline; filename="urls.py"'),
    },
)

The test method is incorrect, but why doesn't this fail on Jenkins? Is Jenkins running the tests on Windows 10 or an older version? The ​Python documentation for mimetypes.guess_type doesn't shed much light, specifically on whether the function returns text/plain for python files on Windows platforms (perhaps previous versions).

[Carlton Gibson]

Hi Addison. This works for me. #32041 came up recently, which is related.

If you can dig-in and come up with some more information we can look into it but short of a concrete analysis I'm not sure what we can do. What action are we to take? (The line in the tests is as it is because this was the behaviour we hit developing the feature…)

[Carlton Gibson]

This has come up again with a ​PR adjusting the test case to pass with either mimetype.

[GitHub <noreply@…>]

In 7618130:

Fixed #31550 -- Adjusted ASGI test_file_response for various Windows content types.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 5dec57a6:

[3.1.x] Fixed #31550 -- Adjusted ASGI test_file_response for various Windows content types.

Backport of 76181308fb02e67794d0cc1471766a5d7e4c877e from master