Tests for 5 classes (Issue #29)

[drhiidden]

Added unit tests for utility classes, builders, and handlers to improve test coverage.

Files

GeminiModels - 7 tests, 96 lines
Model constants for Gemini 2.0/2.5/3.0/3.1. Uses reflection for the private constructor. 100% covered.

StreamingPromptRunnerBuilder - 6 tests, 156 lines
Builder record for streaming prompt execution. Tests exception handling and field validation. 98% (record internals unreachable).

ObservationKeys - 11 tests, 155 lines
Key formatters for observation tracking. Empty strings, special chars, nulls all handled. 100%.

NonEmbabelTracingObservationHandler - 4 tests, 115 lines
Context filter for tracing. Standard contexts pass, Embabel contexts are excluded. 100%.

WaitFor - 11 tests, 176 lines
Java HITL sugar for WaitKt. Tests delegation to fromForm(), confirm(), waitFor(). Null handling and exception types. 100%.

Updates (017e4de)

Applied review feedback:

• Private constructor tests now only verify visibility (no reflection invocation)
• Removed redundant assertNotNull before assertEquals (21 lines cleaned)
• Renamed confirmationThrowsOnNullWhat → confirmationThrowsOnNullPayload
• Removed redundant empty constructor from CustomObservationContext
• Removed redundant test createsHandlerWithTracer

Net: -43 lines of unnecessary code.

Standards

• Copyright headers
• JUnit 5.12.2 / Mockito 5.18.0
• @DisplayName on all tests, camelCase names
• AAA comments (Arrange, Act, Assert)
• Mockito patterns per module (@ExtendWith in observability, private final in api)

39 tests pass.

Run

mvn test -pl embabel-agent-api -Dtest=GeminiModelsTest,StreamingPromptRunnerBuilderTest,WaitForTest
mvn test -pl embabel-agent-observability -Dtest=ObservationKeysTest,NonEmbabelTracingObservationHandlerTest

Thanks for reviewing!

[simeshev]

1. Copyright and licence headers disappeared. Please make sure headers are present.
2. StreamingPromptRunnerBuilderTest is no longer using @ExtendWith(MockitoExtension.class) and @Mock - any particular reason?
3. Add comments // Arrange, // Act, // Assert to the appropriate sections of the tests.

[simeshev]

Looks good now.