TypeScript Test Review

Action required: Run /review typescript test to start an interactive test review. Do not perform the review manually.

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Analyze TypeScript test code for coverage gaps, edge case handling, test quality, and framework-appropriate testing practices.

Scope Determination

First, determine what to review:

1. If the user specifies test files: Review those paths
2. If the user specifies source files: Find corresponding tests and review coverage
3. If no scope specified: Review working changes
   • Check for .jj directory first, use jj diff if present
   • Otherwise use git diff to identify changed files
   • Look at both changed source and test files

Test files are commonly *.test.ts, *.spec.ts, *.test.tsx, or under __tests__/.

Review Process

1. Map source to tests: Identify modules/features lacking meaningful coverage
2. Analyze scenario coverage: happy path, failure path, boundary conditions
3. Review test quality using checklist below
4. Output findings in the standard format

Test Review Checklist

Coverage Gaps

• Public behavior and critical business logic are tested
• Error and exception paths are covered
• Boundary and edge cases covered (empty, nullish, large inputs, invalid formats)
• Authorization/permission-sensitive logic has explicit tests
• Integration boundaries (DB/API/file/network) have representative tests

Test Quality

• Tests verify behavior, not private implementation details
• Names describe intent clearly
• Assertions are specific and meaningful
• Tests are deterministic (no timing/race flakiness)
• Setup and teardown are explicit and isolated
• No hidden inter-test dependencies

Skipped & Disabled Tests

• Flag any use of it.skip, test.skip, describe.skip, xit, xdescribe, xtest, or test.todo — especially if recently added
• Look for tests with trivially passing assertions or empty bodies (a sign the test was gutted to pass)
• Check for commented-out tests or expect(true).toBe(true) placeholder assertions
• Watch for TODO/FIXME comments suggesting the test was too hard to fix and was bypassed instead
• These patterns are HIGH severity when they appear to be workarounds (e.g., an LLM disabling a test it couldn't fix rather than addressing the underlying failure)

Type-Driven Test Practices

• Test fixtures align with actual TypeScript types
• as any in tests minimized and justified
• Mocks/stubs preserve contract shape to avoid false confidence
• Runtime validators tested when used for untrusted input

Framework Patterns (Jest/Vitest/Playwright/etc.)

• Avoids over-mocking that removes behavior under test
• Uses fake timers carefully and restores state
• Async tests await all promises and assert rejection paths
• Snapshot tests are focused and reviewed (not overly broad)
• E2E tests focus on critical flows and failure cases, not only happy paths

Edge Cases & Robustness

• Empty collections/strings, null/undefined, malformed input
• Concurrency/race scenarios where relevant
• Retry/timeout/fallback behavior tested
• Idempotency and duplicate request handling tested where applicable
• Error mapping and user-visible failure responses validated

Property-Based / Fuzz Opportunities

Identify logic that would benefit from generated input testing:

• Parsers, validators, normalizers
• Serialization/deserialization roundtrip behavior
• Business invariants over wide input spaces

Output Format

Present findings as:

## Findings

### [SEVERITY] Issue Title
**File:** `path/to/file.test.ts:LINE` (or source file if missing tests)
**Category:** testing

**Issue:** Description of the testing gap or quality issue.

**Suggestion:** What to test or how to improve, with example if helpful.

**Effort:** trivial|small|medium|large

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Use severity indicators:

• HIGH: Critical untested paths, missing failure/security tests
• MEDIUM: Important edge cases missing, weak assertions
• LOW: Organization and incremental quality improvements

Summary

After all findings, provide:

• Total count by severity
• Coverage summary (areas with/without adequate tests)
• Top testing priorities
• Overall test suite assessment (1-2 sentences)