Supplement: #136507 (comment) , so this only in 3.14 and 3.15.

CC: @hugovk could you review this?

It's probably a good idea to add both success and failure test case for the multiple provided values (e.g., -e image/jpeg text/html, and -e image/jpeg text/xyz).

Could you also test the failure case?

Could you also test the failure case?

Sorry, I might not have understood it well. 9500cb3 Run this test was failing before the fix, now it runs pass after the fix

Could you also test the failure case?

Sorry, I might not have understood it well. 9500cb3 Run this test was failing before the fix, now it runs pass after the fix

I believe there needs to be a test for the sys.exit calls. For example the case of error: media type unknown for dragons to stderr with a non-zero exit code.

Note that this appears to be slightly changing the interface from a streaming model to a fail fast on the first error case.

With this PR we get both results when successful:

❯ ./python.exe -m mimetypes 1.pdf 1.png
type: application/pdf encoding: None
type: image/png encoding: None

Or if it fails on the last one:

❯ ./python.exe -m mimetypes 1.pdf 1.pnx
type: application/pdf encoding: None
error: media type unknown for 1.pnx

But not if it fails on the first one (or both):

❯ ./python.exe -m mimetypes 1.pdx 1.pnx
error: media type unknown for 1.pdx

Shall we collect all results and display them all at the end?

❯ ./python.exe -m mimetypes 1.pdx 1.png
error: media type unknown for 1.pdx
type: image/png encoding: None

Something like this:

diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index d38c6e1aba2..7d0f4c1fd40 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -718,8 +718,6 @@ def _parse_args(args):
 
 def _main(args=None):
     """Run the mimetypes command-line interface and return a text to print."""
-    import sys
-
     args, help_text = _parse_args(args)
 
     results = []
@@ -729,17 +727,21 @@ def _main(args=None):
             if guess:
                 results.append(str(guess))
             else:
-                sys.exit(f"error: unknown type {gtype}")
-        return '\n'.join(results)
+                results.append(f"error: unknown type {gtype}")
+        return results
     else:
         for gtype in args.type:
             guess, encoding = guess_type(gtype, not args.lenient)
             if guess:
                 results.append(f"type: {guess} encoding: {encoding}")
             else:
-                sys.exit(f"error: media type unknown for {gtype}")
-        return '\n'.join(results)
+                results.append(f"error: media type unknown for {gtype}")
+        return results
 
 
 if __name__ == '__main__':
-    print(_main())
+    import sys
+
+    results = _main()
+    print("\n".join(results))
+    sys.exit(any(result.startswith("error: ") for result in results))

Very thanks! Applyed and fixed test

Thanks @Wulian233 for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

GH-138140 is a backport of this pull request to the 3.14 branch.

if name == 'main':

• print(_main())

• import sys
• results = _main()
• print("\n".join(results))
• sys.exit(any(result.startswith("error: ") for result in results))

Why not encapsulate the functionality in _main and have it return tuple[string, int] with the second parameter communicating the exit code?

Also, it would be better if errors were written to stderr, not stdout.