testing-gaps

# Testing Gaps Find untested branches and missing real-world test scenarios for a source file. ## Workflow 1. **Run text coverage** for the target file 2. **Identify uncovered branches** from the output 3. **Cross-reference** with test file to understand what's tested 4. **Report** uncovered branches + missing real-world scenarios ## Step 1: Run Coverage Use `cargo llvm-cov` with `--text` output (not `--html`) for parseable results. ```bash # Full coverage, filtered to target file cargo llvm-cov test --text \ --ignore-run-fail \ --ignore-filename-regex '(_test.rs|\/test\/)' \ 2>/dev/null | sed -n '/TARGET_FILE\.rs:/,/^$/p' ``` Example for `preferred_semver.rs`: ```bash cargo llvm-cov test --text \ --ignore-run-fail \ --ignore-filename-regex '(_test.rs|\/test\/)' \ 2>/dev/null | sed -n '/preferred_semver\.rs:/,/^$/p' ``` ## Step 2: Read Coverage Output The text format shows per-line execution counts: ``` 42| 80| .and_then(|range| ...) # Hit 80 times 74| 0| Some(preferred) # Never hit 321| 0| instance.mark_conflict(...) # Never hit ``` - `count > 0` = covered - `count = 0` = uncovered branch - `^N` annotations on sub-expressions show partial coverage within a line ### Extract only uncovered lines ```bash ... | grep -E '^\s+\d+\|\s+0\|' ``` ## Step 3: Classify Gaps For each uncovered branch, determine: 1. **What code path leads here?** — Trace the `if/else` chain backward 2. **What input would trigger it?** — What package.json + config combination 3. **Is it reachable?** — Some branches may be defensive/unreachable 4. **Is it worth testing?** — Real-world scenario vs theoretical edge case ### Categories | Category | Action | | -------------------------------- | ----------------- | | Real-world scenario never tested | Write a test | | Edge case in existing logic | Write a test | | Defensive branch (unreachable) | Note but skip | | Dead code | Consider removing | ## Step 4: Identify Missing Scenarios Beyond line coverage, look for missing _combinations_: - Feature A tested, Feature B tested, A+B never tested together - Only tested with one package, never with multiple - Only tested with `highestSemver`, never `lowestSemver` - Only tested with one range type (`^`), never others (`>=`, `<=`) - Only tested without semver groups, never with ## Step 5: Report Structure findings as: 1. **Uncovered branches** — Specific lines, what triggers them, why untested 2. **Missing real-world scenarios** — Combinations and interactions not covered ## Running Tests After Adding Coverage ```bash just test # All tests cargo test test_name -- --nocapture # Specific test just coverage # Regenerate coverage report ```