# Unit Testing Implementation

**Status**: In Progress  
**Owner**: Theater Team  
**Reference Change**: [2025-04-01-unit-testing-implementation.md](/changes/proposals/2025-04-01-unit-testing-implementation.md)

## Overview

This change implements comprehensive unit and integration tests for key Theater components as outlined in the original proposal.

## Progress

### Completed

- ✅ Created test directory structure
- ✅ Implemented test utilities (mocks and helpers)
- ✅ Added StateChain unit tests
- ✅ Added ActorStore unit tests
- ✅ Added ActorHandle unit tests (basic functionality)
- ✅ Added ContentStore unit tests
- ✅ Added message serialization/deserialization tests
- ✅ Fixed component compatibility issues

### In Progress

- ⏳ Implement ActorHandle call_function tests with proper ComponentType traits
- ⏳ Complete handler interface mocks and tests
- ⏳ Implement full lifecycle integration tests

### Pending

- ⏳ Add supervision tests
- ⏳ Add CI integration
- ⏳ Update documentation with examples

## Next Steps

1. Complete the mock WASM component to enable full actor runtime testing
2. Create mocks for handler interfaces to test handler interactions
3. Add integration tests for messaging between multiple actors
4. Add CI configuration to run tests on PRs and main branch
5. Measure test coverage and identify gaps
6. Document testing patterns and best practices

## Issues/Questions

- Need to determine the best approach for mocking WASM components in tests
- Our attempt to implement unit tests found several API differences from expected:
  - MessageEventData is an enum, not a struct
  - ActorMetrics has a different structure than originally expected
  - ContentStore API has changed (methods and parameter types)
- Consider using a separate test fixture for integration tests to avoid slow compile times
- Investigate test coverage reporting options

## Implementation Notes

### Mock WASM Component Strategy

To effectively test the actor runtime without requiring real WASM components, we need to develop a comprehensive mocking strategy:

1. Create a `MockActorInstance` that implements the same interface as real actor instances
2. Implement controlled responses for function calls
3. Add the ability to simulate errors and timeouts
4. Create factories for generating common test actors

### Handler Interface Testing

For testing handler interfaces:

1. Create mock implementations of each handler type
2. Implement controlled behavior for testing specific scenarios
3. Add utilities for verifying handler lifecycle events
4. Test interactions between handlers and actors

### Integration Test Strategy

For end-to-end testing:

1. Create a fixture with a real Theater runtime but mock actors
2. Test complete actor lifecycle (create → initialize → message → terminate)
3. Test parent-child supervision scenarios
4. Test error handling and recovery

## Completion Criteria

This change will be considered complete when:

1. All planned unit and integration tests are implemented
2. Test coverage exceeds 70% for core components
3. CI integration is complete
4. Documentation is updated with testing examples and guidance
5. All tests pass reliably without flakiness