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gh-131178: Fix mimetypes CLI docs to mention that errors go to stdout #149683

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Merged
sobolevn merged 10 commits into from
May 31, 2026
Merged

gh-131178: Fix mimetypes CLI docs to mention that errors go to stdout #149683

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c87667b
gh-149682: Fix mimetypes CLI to write error messages to stderr
htjworld May 11, 2026
77e5b2a
Remove inline comments from docs examples
htjworld May 11, 2026
5b75aaa
Address review feedback: revert stderr routing, update docs and tests
htjworld May 11, 2026
ad605cd
Add NEWS entry for mimetypes CLI tests
htjworld May 11, 2026
f6db7b1
Address review feedback: strengthen test assertions, remove NEWS entry
htjworld May 11, 2026
edf95da
gh-131178: fix test_unknown_flag to supply positional arg
htjworld May 12, 2026
b00896c
gh-131178: add @force_not_colorized to test_unknown_flag
htjworld May 12, 2026
e0409b3
Merge branch 'main' into gh-149682-mimetypes-fix-stderr
sobolevn May 31, 2026
277b007
gh-131178: revert unnecessary CLI example changes in mimetypes docs
htjworld May 31, 2026
4b28aed
Update Doc/library/mimetypes.rst
htjworld May 31, 2026
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18 changes: 8 additions & 10 deletions Doc/library/mimetypes.rst
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Expand Up @@ -348,7 +348,7 @@ it converts file extensions to MIME types.

For each ``type`` entry, the script writes a line into the standard output
stream. If an unknown type occurs, it writes an error message into the
standard error stream and exits with the return code ``1``.
standard output stream and exits with the return code ``1``.


.. mimetypes-cli-example:
Expand All @@ -373,13 +373,9 @@ interface:
$ python -m mimetypes filename.tar.gz
type: application/x-tar encoding: gzip

$ # get a MIME type for a rare file extension
$ python -m mimetypes filename.pict
error: unknown extension of filename.pict

$ # now look in the extended database built into Python
$ python -m mimetypes --lenient filename.pict
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type: image/pict encoding: None
$ # get a MIME type for an unknown file extension
$ python -m mimetypes filename.zzz
error: media type unknown for filename.zzz

$ # get a file extension by a MIME type
$ python -m mimetypes --extension text/javascript
Expand All @@ -394,13 +390,15 @@ interface:
.xul

$ # try to feed an unknown file extension
$ python -m mimetypes filename.sh filename.nc filename.xxx filename.txt
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$ python -m mimetypes filename.sh filename.nc filename.zzz filename.txt
type: application/x-sh encoding: None
type: application/x-netcdf encoding: None
error: unknown extension of filename.xxx
error: media type unknown for filename.zzz
type: text/plain encoding: None

$ # try to feed an unknown MIME type
$ python -m mimetypes --extension audio/aac audio/opus audio/future audio/x-wav
.aac
.opus
error: unknown type audio/future
.wav
55 changes: 54 additions & 1 deletion Lib/test/test_mimetypes.py
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Expand Up @@ -6,8 +6,9 @@
import unittest.mock
from platform import win32_edition
from test import support
from test.support import cpython_only, force_not_colorized, os_helper
from test.support import cpython_only, force_not_colorized, os_helper, requires_subprocess
from test.support.import_helper import ensure_lazy_imports
from test.support.script_helper import assert_python_ok, assert_python_failure

try:
import _winapi
Expand Down Expand Up @@ -508,5 +509,57 @@ def test_invocation_error(self):
self.assertEqual(result, expected)


@requires_subprocess()
class CommandLineSubprocessTest(unittest.TestCase):
def test_help(self):
rc, stdout, stderr = assert_python_ok('-m', 'mimetypes', '--help')
self.assertIn(b'mimetypes', stdout)
self.assertIn(b'--extension', stdout)
self.assertIn(b'--lenient', stdout)

def test_type_lookup(self):
rc, stdout, stderr = assert_python_ok('-m', 'mimetypes', 'foo.pdf')
self.assertEqual(stdout.strip(), b'type: application/pdf encoding: None')
self.assertEqual(stderr, b'')

def test_type_lookup_unknown(self):
rc, stdout, stderr = assert_python_failure('-m', 'mimetypes', 'foo.unknownext12345')
self.assertEqual(stdout.strip(), b'error: media type unknown for foo.unknownext12345')
self.assertEqual(stderr, b'')

def test_extension_flag(self):
rc, stdout, stderr = assert_python_ok('-m', 'mimetypes', '-e', 'image/jpeg')
self.assertIn(b'.jpg', stdout)

@sobolevn sobolevn May 11, 2026

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Let's use assertEqual here as well.

self.assertEqual(stderr, b'')

def test_extension_flag_unknown(self):
rc, stdout, stderr = assert_python_failure('-m', 'mimetypes', '-e', 'image/unknowntype12345')
self.assertEqual(stdout.strip(), b'error: unknown type image/unknowntype12345')
self.assertEqual(stderr, b'')

def test_lenient_flag(self):
rc, stdout, stderr = assert_python_ok('-m', 'mimetypes', '-e', '--lenient', 'text/xul')
self.assertIn(b'.xul', stdout)
self.assertEqual(stderr, b'')

def test_multiple_inputs(self):
rc, stdout, stderr = assert_python_ok('-m', 'mimetypes', 'foo.pdf', 'foo.png')
self.assertIn(b'type: application/pdf encoding: None', stdout)
self.assertIn(b'type: image/png encoding: None', stdout)
self.assertEqual(stderr, b'')

def test_multiple_inputs_with_error(self):
rc, stdout, stderr = assert_python_failure(
'-m', 'mimetypes', 'foo.pdf', 'foo.unknownext12345'
)
self.assertIn(b'type: application/pdf encoding: None', stdout)
self.assertIn(b'error: media type unknown for foo.unknownext12345', stdout)
self.assertEqual(stderr, b'')

def test_unknown_flag(self):
rc, stdout, stderr = assert_python_failure('-m', 'mimetypes', '--unknown-flag')
self.assertNotEqual(rc, 0)

@sobolevn sobolevn May 11, 2026

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assert the output please :)



if __name__ == "__main__":
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Tests/2026-05-12-00-35-20.gh-issue-131178.mX9pQa.rst
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@@ -0,0 +1,2 @@
Add subprocess-based tests for the :mod:`mimetypes` command-line interface,

@sobolevn sobolevn May 11, 2026

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we don't add news for docs / tests only changes.

verifying output format and exit codes for known and unknown types.
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