---
phase: 01-junction-fix-root-cause
plan: "02"
subsystem: streaming
tags: [rust, unit-tests, junction-fill, stathera, gap-detection]

requires:
  - phase: 01-junction-fix-root-cause/01
    provides: junction fill implementation in symbol_task

provides:
  - 4 unit tests validating all JUNC-* success criteria
  - Regression safety net for junction fill logic

affects: [phase-2-telemetry, phase-8-integration]

tech-stack:
  added: []
  patterns:
    - "Synchronous #[test] for gap detector + processor validation (no tokio runtime needed)"

key-files:
  created: []
  modified:
    - crates/opendeviationbar-streaming/src/live_engine.rs

key-decisions:
  - "Used synchronous #[test] instead of #[tokio::test] since tests exercise processor and gap detector directly without async I/O"

patterns-established:
  - "Junction test pattern: create processor + gap detector, simulate REST phase, then validate WS transition invariants"

requirements-completed: [JUNC-01, JUNC-02, JUNC-03, JUNC-04]

duration: 5 min
completed: 2026-03-19
---

# Phase 1 Plan 2: Junction Fill Unit Tests Summary

**4 unit tests validating zero Stathera gaps, Puck suppression, forming bar preservation, and monotonicity guard across REST-to-WS junction**

## Performance

- **Duration:** 5 min
- **Started:** 2026-03-19T21:40:02Z
- **Completed:** 2026-03-19T21:44:44Z
- **Tasks:** 5 (4 test implementations + 1 full suite verification)
- **Files modified:** 1

## Accomplishments

- Added `test_junction_fill_zero_stathera_gaps`: validates JUNC-03 (gap detector re-seed) and JUNC-01 (forming bar preserved)
- Added `test_junction_zero_gap_no_fill_needed`: validates happy path where first WS trade continues exactly from REST
- Added `test_junction_monotonicity_guard`: validates JUNC-04 (overlapping WS trades detected and droppable)
- Added `test_junction_forming_bar_trade_count_preserved`: validates JUNC-01/JUNC-02 (single processor carries trades across REST, junction, WS)
- Full suite: 87 tests pass, cargo clippy clean, cargo check clean

## Task Commits

Each task was committed atomically:

1. **Task 02-01: Junction fill zero Stathera gaps test** - `5224a3e` (test)
2. **Task 02-01b: Zero-gap junction path test** - `e018eb1` (test)
3. **Task 02-02: Monotonicity guard test** - `1f23092` (test)
4. **Task 02-03: Forming bar trade count preservation test** - `dfa9e51` (test)
5. **Task 02-04: Full suite verification** - no commit (verification only)

## Files Created/Modified

- `crates/opendeviationbar-streaming/src/live_engine.rs` - Added 4 unit tests to `mod tests` block

## Decisions Made

- Used synchronous `#[test]` instead of `#[tokio::test]` since tests exercise processor and gap detector directly without async I/O
- Tests require `--features binance-integration` since `live_engine` module is behind that feature gate (pre-existing condition, not a deviation)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

- Integration test files (`gap_edge_cases.rs`, `gap_event_tests.rs`, `reconnect_gap_fill.rs`) have pre-existing compilation errors unrelated to this change. Used `cargo test --lib` instead of `cargo nextest run` to isolate lib-only tests. All 87 lib tests pass.

## Next Phase Readiness

- Phase 1 complete: all 4 JUNC-\* requirements implemented (Plan 01) and tested (Plan 02)
- Ready for Phase 2 (Junction Telemetry + Audit Items)
