I need a comprehensive unit-test suite that verifies my runtime library still works flawlessly on Android 16 (API level 16) before it ships through Google Play. A handful of JUnit tests already cover basic paths; the job is to expand that set into full coverage so every public method, edge case, and error branch is exercised. The project lives in a Gradle repo and builds with Android Studio Flamingo. Please grow the existing test module, keeping the current naming conventions, and use JUnit 4/5 together with Robolectric or any other framework that lets the suite run headless on the CI server. MockK and Mockito are both wired in if you need them. Deliverables • Clean, self-documenting test code committed to a new branch • A coverage report showing at least 90 % line coverage on API 16 stubs • Updated CI workflow so the suite runs with ./gradlew test • A short README outlining setup, commands, and any new dependencies Acceptance criteria: all tests pass on API 16 emulation, the build stays green for higher API levels, and no existing functionality is broken or suppressed.