TestGen Skill - AI Test Generation

testgen <target> [--type] [--focus] [--depth]
    │
    ├─→ Step 1: Analyze Target
    │     ├─ File exists? → Read and parse
    │     ├─ Function specified? → Extract signature
    │     ├─ Directory? → List source files
    │     └─ Find existing tests (avoid duplicates)
    │
    ├─→ Step 2: Detect Framework (parallel)
    │     ├─ package.json → jest/vitest/mocha/cypress/playwright
    │     ├─ pyproject.toml → pytest/unittest
    │     ├─ go.mod → go test
    │     ├─ Cargo.toml → cargo test
    │     ├─ composer.json → phpunit/pest
    │     └─ Check existing test patterns
    │
    ├─→ Step 3: Load Project Standards
    │     ├─ AGENTS.md, CLAUDE.md conventions
    │     ├─ Existing test file structure
    │     └─ Naming conventions (*.test.ts vs *.spec.ts)
    │
    ├─→ Step 4: Route to Expert Agent
    │     ├─ .ts → typescript-expert
    │     ├─ .tsx/.jsx → react-expert
    │     ├─ .vue → vue-expert
    │     ├─ .py → python-expert
    │     ├─ .go → go-expert
    │     ├─ .rs → rust-expert
    │     ├─ .php → laravel-expert
    │     ├─ E2E/Cypress → cypress-expert
    │     ├─ Playwright → typescript-expert
    │     ├─ --visual → Chrome DevTools MCP
    │     └─ Multi-file → parallel expert dispatch
    │
    ├─→ Step 5: Generate Tests
    │     ├─ Create test file in correct location
    │     ├─ Follow detected conventions
    │     └─ Include: happy path, edge cases, error handling
    │
    └─→ Step 6: Integration
          ├─ Auto-create task (TaskCreate) for verification
          └─ Suggest: run tests, /review, /save

# Check if target exists
test -f "$TARGET" && echo "FILE" || test -d "$TARGET" && echo "DIRECTORY"

# For function-specific: extract signature
command -v ast-grep >/dev/null 2>&1 && ast-grep -p "function $FUNCTION_NAME" "$FILE"

# Fallback to ripgrep
rg "(?:function|const|def|public|private)\s+$FUNCTION_NAME" "$FILE" -A 10

fd -e test.ts -e spec.ts -e test.js -e spec.js | rg "$BASENAME"
fd "test_*.py" | rg "$BASENAME"

cat package.json 2>/dev/null | jq -r '.devDependencies | keys[]' | grep -E 'jest|vitest|mocha|cypress|playwright|@testing-library'

grep -E "pytest|unittest|nose" pyproject.toml setup.py requirements*.txt 2>/dev/null

test -f go.mod && echo "go test available"

test -f Cargo.toml && echo "cargo test available"

cat composer.json 2>/dev/null | jq -r '.["require-dev"] | keys[]' | grep -E 'phpunit|pest|codeception'

# Claude Code conventions
cat AGENTS.md 2>/dev/null | head -50
cat CLAUDE.md 2>/dev/null | head -50

# Test config files
cat jest.config.* vitest.config.* pytest.ini pyproject.toml 2>/dev/null | head -30

# JavaScript
src/utils/helper.ts → src/utils/__tests__/helper.test.ts  # __tests__ folder
                    → src/utils/helper.test.ts            # co-located
                    → tests/utils/helper.test.ts          # separate tests/

# Python
app/utils/helper.py → tests/test_helper.py               # tests/ folder
                    → tests/utils/test_helper.py         # mirror structure

# Go
pkg/auth/token.go → pkg/auth/token_test.go               # co-located (required)

# Rust
src/auth.rs → src/auth.rs (mod tests { ... })            # inline tests
            → tests/auth_test.rs                          # integration tests

Task tool with subagent_type: "[detected]-expert"
Prompt includes:
  - Source file content
  - Function signatures to test
  - Detected framework and conventions
  - Requested test type and focus

TaskCreate:
  subject: "Run generated tests for src/auth.ts"
  description: "Verify generated tests pass and review edge cases"
  activeForm: "Running generated tests for auth.ts"

Tests generated: src/auth.test.ts

Next steps:
1. Run tests: npm test src/auth.test.ts
2. Review and refine edge cases
3. Use /save to persist tasks across sessions

command -v jq >/dev/null 2>&1 && cat package.json | jq '.devDependencies' || cat package.json