Minimal unit test coverage: no tests for transforms, sensors, networking, or Signal K

[mairas]

Description

The project has only 6 test files covering:

• CRGB color type
• ValueProducer lifecycle
• Event loop initialization
• LED blinker patterns
• TaskQueueProducer
• Basic offline functionality

Not tested: Any transform, any sensor, Signal K protocol, networking, configuration persistence, JSON serialization, or the entire connect_to pipeline.

Given the number of correctness bugs found in this review (variable shadowing, assignment typos, buffer resize bugs, uninitialized values), the lack of unit tests for transforms is a significant risk.

Recommendation

Priority areas for test coverage:

1. Transforms -- especially CurveInterpolator, MovingAverage, LambdaTransform, Hysteresis, Frequency
2. JSON serialization -- to_json/from_json round-trip tests for all configurable objects
3. Nullable -- edge cases for each type specialization
4. Multi-input transforms -- once a unified pattern is designed (see No unified multi-input transform pattern (three inconsistent approaches) #899)

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Found during code review (2026-03-25)