Fix isLibraryLoaded per-loader scope

[dlanov]

Fixes #173.

Summary

ClassLoader::isLibraryLoaded() is documented to report whether a library is loaded within the scope of that specific loader.

The previous comparison used <= when comparing the number of metaobjects owned by the loader with the total number of metaobjects for the library. Because the loader-owned metaobjects are a subset of the total, this could report the library as loaded for an on-demand loader that had not loaded it.

Require the counts to match and add a regression test using two loaders for the same library. The test verifies that:

• the on-demand loader initially reports the library as not loaded
• it reports loaded after loadLibrary()
• unloading it does not affect the other loader
• the library is no longer globally loaded after the final loader unloads it

Testing

Validated in ros:rolling-ros-base:

• colcon build --packages-select class_loader --cmake-args -DBUILD_TESTING=ON
• colcon test --packages-select class_loader
• 135 tests, 0 errors, 0 failures, 25 skipped
• ClassLoaderTest.isLibraryLoadedScopedToLoader passed
• git diff --check

Generative AI

Generative AI assisted with issue analysis, preparing the scoped edit, and test planning. I reviewed the complete diff and all test results.

[mergify]

Tick the box to add this pull request to the merge queue (same as @mergifyio queue).

• Queue this pull request