swev-id: django__django-16642 Fix FileResponse content encoding

[casey-brooks]

Summary

• set FileResponse Content-Type from the underlying resource while inferring Content-Encoding for known compression suffixes (.Z, .gz, .bz2, .xz, .br)
• keep explicit content_type untouched and expand regression coverage for the new encoding rules
• align the response headers with HTTP semantics by separating representation metadata from transfer codings

Reproduction

from django.http import FileResponse

FileResponse(open("test.html.br", "rb"))
FileResponse(open("test.html.Z", "rb"))

PYTHONPATH=$PWD:$HOME/.nix-profile/lib/python3.11/site-packages \
DJANGO_SETTINGS_MODULE=tests.test_sqlite \
python3.11 tests/runtests.py responses --parallel=1

Observed failure

Testing against Django installed in '/workspace/django/django'
Found 56 test(s).
System check identified no issues (0 silenced).
.................FFF.....EE...............................
======================================================================
ERROR: test_content_encoding_Z_suffix (responses.test_fileresponse.FileResponseTests.test_content_encoding_Z_suffix)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/workspace/django/tests/responses/test_fileresponse.py", line 269, in test_content_encoding_Z_suffix
    self.assertEqual(response.headers["Content-Encoding"], "compress")
                     ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/workspace/django/django/utils/datastructures.py", line 308, in __getitem__
    return self._store[key.lower()][1]
           ~~~~~~~~~~~^^^^^^^^^^^^^
KeyError: 'content-encoding'

======================================================================
ERROR: test_content_encoding_br_suffix (responses.test_fileresponse.FileResponseTests.test_content_encoding_br_suffix)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/workspace/django/tests/responses/test_fileresponse.py", line 275, in test_content_encoding_br_suffix
    self.assertEqual(response.headers["Content-Encoding"], "br")
                     ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/workspace/django/django/utils/datastructures.py", line 308, in __getitem__
    return self._store[key.lower()][1]
           ~~~~~~~~~~~^^^^^^^^^^^^^
KeyError: 'content-encoding'

======================================================================
FAIL: test_compressed_response (responses.test_fileresponse.FileResponseTests.test_compressed_response) (ext='.tar.gz')
FileResponse infers the underlying Content-Type and sets
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/workspace/django/tests/responses/test_fileresponse.py", line 262, in test_compressed_response
    self.assertEqual(response.headers["Content-Type"], mimetype)
AssertionError: 'application/gzip' != 'application/x-tar'
- application/gzip
+ application/x-tar


======================================================================
FAIL: test_compressed_response (responses.test_fileresponse.FileResponseTests.test_compressed_response) (ext='.tar.bz2')
FileResponse infers the underlying Content-Type and sets
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/workspace/django/tests/responses/test_fileresponse.py", line 262, in test_compressed_response
    self.assertEqual(response.headers["Content-Type"], mimetype)
AssertionError: 'application/x-bzip' != 'application/x-tar'
- application/x-bzip
?               ^^^^
+ application/x-tar
?               ^^^


======================================================================
FAIL: test_compressed_response (responses.test_fileresponse.FileResponseTests.test_compressed_response) (ext='.tar.xz')
FileResponse infers the underlying Content-Type and sets
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/workspace/django/tests/responses/test_fileresponse.py", line 262, in test_compressed_response
    self.assertEqual(response.headers["Content-Type"], mimetype)
AssertionError: 'application/x-xz' != 'application/x-tar'
- application/x-xz
?               ^^
+ application/x-tar
?               ^^^


----------------------------------------------------------------------
Ran 56 tests in 0.011s

FAILED (failures=3, errors=2)

Testing

• PYTHONPATH=$PWD:$HOME/.nix-profile/lib/python3.11/site-packages DJANGO_SETTINGS_MODULE=tests.test_sqlite python3.11 tests/runtests.py responses --parallel=1

Fixes #512

[casey-brooks]

Test & Lint Summary

• PYTHONPATH=$PWD:$HOME/.nix-profile/lib/python3.11/site-packages DJANGO_SETTINGS_MODULE=tests.test_sqlite python3.11 tests/runtests.py responses --parallel=1 → 56 passed, 0 failed, 0 skipped
• PYTHONPATH=$PWD:$HOME/.nix-profile/lib/python3.11/site-packages python3.11 -m flake8 django/http/response.py tests/responses/test_fileresponse.py → no lint errors

[noa-lucent]

Specs met: FileResponse now preserves underlying Content-Type and emits Content-Encoding for known compressed suffixes, and regression coverage exercises the new paths.

[noa-lucent]

LGTM