[objective_c] Use user_defines to gate test utilities in build hook (Fixes #2999)

[Gurleen-kansray]

Description

Replaces the objective_c_helper package approach from #3129 with a simpler solution using user_defines in the build hook, as suggested by @liamappelbe.

The core idea: user_defines declared in pubspec.yaml are only visible to the build hook when that package is the root/development package, not when it is a transitive dependency. This means test/util.c is only compiled into the dylib when actively developing objective_c, keeping the production binary clean.

Changes

• Removed the testFiles constant and the macOS-only gate from hook/build.dart, replacing them with a user_defines-based gate (include_test_utils)
• Added hook.user_defines (include_test_utils: false) to pubspec.yaml
• Updated CHANGELOG.md

Note: Will keep an eye on #3307, once it lands, gc_inject.m should be gated with the same include_test_utils define.

Related Issues

Fixes #2999
Supersedes #3129

PR Checklist

• I've reviewed the contributor guide and applied the relevant portions to this PR.
• All existing tests are passing. No new tests were needed — this is a build infrastructure change with no behavioral difference for end users.
• The PR is actually solving the issue — test/util.c is no longer unconditionally compiled into the production dylib.
• I have updated CHANGELOG.md for the objective_c package.
• No pubspec version bump needed — this is an internal build infrastructure change with no public API changes.

[liamappelbe]

This should be true.

[liamappelbe]

From a user's perspective, they only care that some unnecessary stuff has been removed from the dylib. So how about "Removed some test-only utilities from the release dylib (fixes ..."

[github-actions]

PR Health

Changelog Entry ✔️

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Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
objective_c	Breaking	9.3.0	9.4.0-wip	9.4.0-wip	✔️

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[Gurleen-kansray]

Addressed. Updated the default value and the changelog description. Thanks for the quick review @liamappelbe!

[liamappelbe]

nit: This sort of # shorthand doesn't work if the file isn't being viewed on github (eg on pub.dev). Use the same format as the other changelog entries.

[Gurleen-kansray]

Fixed the changelog link format to use the full URL. Ready for another look, thanks!

[liamappelbe]

does this work when you run it locally? On CI I'm seeing errors that look like util.c is never included

Eg: https://github.com/dart-lang/native/actions/runs/24811893252/job/72618483240?pr=3325. nsset_test.dart is a simple one to look at.

[Gurleen-kansray]

Sorry about that @liamappelbe! The pubspec.yaml structure was wrong, I had the define at the top level instead of nested under the package name, and was comparing as a string instead of a bool. I've now fixed both:

• pubspec.yaml: nested include_test_utils: true under objective_c: (the package name), matching the pattern in the download_asset example
• build.dart: changed the comparison to as bool? ?? false

I can't run the hook locally since I'm on Windows, but the fix should resolve the CI failures. Sorry for the noise!

[liamappelbe]

Looks pretty good. But you've got some formatting errors: https://github.com/dart-lang/native/actions/runs/24813053011/job/72801287014?pr=3325

[Gurleen-kansray]

Fixed the formatting errors across the modified files. Ready for another look, thanks @liamappelbe :)

[liamappelbe]

Ok, looking closer at the errors, I think the issue is that util.dart is using the wrong @Native annotation. You should read about how @Native annotations relate to build hooks, but I think the quick fix is just to specify the asset id in the annotation, and make sure it matches the one in the build hook.

[Gurleen-kansray]

Thanks @liamappelbe! Added assetId: 'package:objective_c/objective_c.dylib' to both @Native annotations in util.dart, matching the asset name defined in the build hook. Let me know if that's the right value.

[liamappelbe]

Ok, the errors have changed a bit. Now they're complaining that the dylib doesn't contain the symbol. That's going to be hard for you to debug without a mac. I'll clone your PR and take a look.

[Gurleen-kansray]

Thanks @liamappelbe, really appreciate you taking the time to clone and debug this directly. I'll wait for your findings!

[Gurleen-kansray]

Thank you so much @liamappelbe for the fixes, the review, and for taking the time to debug this directly on your Mac.