Unit tests for signal engine (packages/core)

[naimkatiman]

Tests: Signal Engine Unit Test Coverage

Current state

The signal engine in packages/core/src/signals/engine.ts has little to no unit test coverage. This is a critical path — signal logic bugs directly affect users.

What to test

For each indicator function, write tests covering:

1. RSI calculator

   • RSI > 70 → SELL vote
   • RSI < 30 → BUY vote
   • RSI 30–70 → HOLD vote
   • Edge cases: empty data, single candle

2. MACD crossover

   • MACD crosses above signal line → BUY
   • MACD crosses below signal line → SELL
   • No crossover → HOLD

3. Bollinger Band squeeze

   • Bands narrow (squeeze) + breakout up → BUY
   • Bands narrow (squeeze) + breakout down → SELL

4. EMA crossover

   • 9 EMA crosses above 21 EMA → BUY
   • 9 EMA crosses below 21 EMA → SELL

5. Signal aggregator

   • 4 BUY votes, 1 SELL → final signal = BUY
   • Verify confidence score calculation

Tech

• Test framework: Jest or Vitest (match whatever is in package.json)
• Mock OHLCV data: use fixture files in __tests__/fixtures/

Acceptance criteria

• 80%+ line coverage on packages/core/src/signals/engine.ts
• All indicator edge cases tested
• Tests run via npm test in CI
• No false positives (tests pass on correct logic, fail on broken logic)

Good first issue because

Pure unit tests — no infrastructure, no Docker, just TypeScript and test fixtures.