CoversClass does not transitively target traits used by enumerations

[no-simpler]

Problem

When a class uses a trait, #[CoversClass(TheClass::class)] transitively whitelists the trait's lines for coverage. When an enum uses the same trait, the trait's lines are not whitelisted — PHPUnit flags the test as risky:

This test executed code that is not listed as code to be covered or used: …

This forces authors to add #[UsesTrait] or #[CoversTrait] to enum tests, which is inconsistent with the class behavior and creates friction with static analysis tools that don't accept those attributes.

A minimal reproduction is available at https://github.com/no-simpler/phpunit-psalm-trit-catch22 (rows 1 vs 4 in its test matrix).

Root cause

CodeUnitFindingVisitor::leaveNode() resolves trait usages only for Class_ and Trait_ nodes. Enum_ extends ClassLike (not Class_), so it is excluded by the early-return gate. Enums are correctly discovered in enterNode() via processClass(), but their trait lists are never populated.

Changes

Three one-line fixes in CodeUnitFindingVisitor:

1. leaveNode() — include Enum_ in the gate so enums proceed to trait resolution
2. postProcessClassOrTrait() signature — widen the type union to accept Enum_
3. postProcessClassOrTrait() body — route Enum_ into the class branch (enums are stored in $this->classes)

Plus a regression test (testHandlesEnumUsingTrait) and fixture file mirroring the existing testHandlesTraitUsingTrait pattern.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.97%. Comparing base (8d03d7a) to head (ecbea80).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1145   +/-   ##
=========================================
  Coverage     96.97%   96.97%           
- Complexity     1480     1482    +2     
=========================================
  Files           110      110           
  Lines          5057     5057           
=========================================
  Hits           4904     4904           
  Misses          153      153           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[sebastianbergmann]

As a bug fix, this should target the 12.5 branch. Thank you!

[sebastianbergmann]

This branch cannot be rebased due to conflicts, likely because something went wrong when changing the target branch. Might be easier to close this and send a fresh pull request against 12.5.

[no-simpler]

I switched target branch in UI and immediately felt stupid. I will re-create the change on correct branch when I get back to my desk.

[sebastianbergmann]

I switched target branch in UI and immediately felt stupid. I will re-create the change on correct branch when I get back to my desk.

No worries :) Thank you for working on this.

[no-simpler]

Superseded by !1147.