Extract and unit-test BootstrapManager::getTestDirPath()

[remyperona]

🤖 AI-generated — created by an automated pipeline. Review before acting on this.

Context
PR #55 (issue #52) made src/{Unit,Integration}/bootstrap.php self-locating via BootstrapManager::setupConstants(). During grooming, an optional testability refactor ("Option B") was deferred: extracting the test-directory default resolution logic into a dedicated helper function to improve unit test coverage. This is a nice-to-have enhancement that reduces maintenance burden in downstream repos (#30) while improving this package's own test coverage.

Dependencies
#52 / PR #55 (already shipped)

What needs to be done

1. Extract the test-directory default resolution from src/BootstrapManager::setupConstants() into a new protected static function getTestDirPath( $which_testsuite ) that returns the relative path (path= override if present, else 'Tests/' . ucfirst( $which_testsuite )), and have setupConstants() call it.
2. Create a new per-method unit test Tests/Unit/BootstrapManager/getTestDirPath.php with a Test_getTestDirPath class following the repo's one-class-per-method convention, with data providers under Tests/Fixtures/BootstrapManager/.
3. (Optionally, b1) Make setupConstants() internally idempotent by wrapping each define() in its own if ( ! defined() ) check for defense-in-depth.

Acceptance Criteria

• New getTestDirPath() function exists, is documented, and is called by setupConstants()
• New unit test file covers: no path= override (defaults to Tests/Unit and Tests/Integration), explicit path= override, trailing-slash handling
• All existing tests pass (no regressions in setupConstants() behavior)
• Test fixture files follow the repo's naming and structure conventions

Additional information
Why it matters: The setupConstants() path is process-global and irreversible; every process in this package's own suite pre-defines the constants via init-tests.php, leaving the default-path branch untested. Extracting a pure helper makes that branch testable using the same approach as getRootDir().

References: Contributes to #30 (reduce per-plugin test maintenance); follow-up to #52 / PR #55.