Marketplace backend-test-writer

Use when generating tests for backend code (Express routes, MongoDB models, Node services) - analyzes file type, detects test framework from package.json, generates comprehensive tests with setup/teardown and edge case coverage

install

source · Clone the upstream repo

git clone https://github.com/aiskillstore/marketplace

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/aiskillstore/marketplace "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/9tykeshav/backend-test-writer" ~/.claude/skills/aiskillstore-marketplace-backend-test-writer && rm -rf "$T"

manifest: skills/9tykeshav/backend-test-writer/SKILL.md

Backend Test Writer

Generate comprehensive backend tests for MERN stack code. Analyzes file type, detects project conventions, produces tests that actually run.

Philosophy: Smart defaults, zero config. Detect everything from project.

Workflow

Copy and track progress:

Phase 0: Infrastructure check
Phase 1: Analyze target files
Phase 2: Generate tests
Phase 3: Report summary

Phase 0: Infrastructure Check

Before generating tests, verify setup:

Check
```
package.json
```
for test framework (Jest/Vitest/Mocha)
If none → prompt: "Set up Jest + Supertest?"
Check for
```
mongodb-memory-server
```
(needed for integration tests)
Detect test file convention (colocated vs
```
__tests__/
```
vs
```
tests/
```
)

Stop if: No test framework and user declines setup.

Phase 1: Analyze Target Files

Pattern	Type	Test Approach
`routes/` , `*.routes.js`	Route	Integration (Supertest + real DB)
`controllers/`	Controller	Integration
`services/`	Service	Unit (mocked deps)
`models/` , `*.model.js`	Model	Unit (validation tests)
`middleware/`	Middleware	Unit (mock req/res/next)
`utils/` , `helpers/`	Utility	Unit (pure functions)

Override: User can specify

--unit

--integration

Phase 2: Generate Tests

Process files sequentially with progress. User can stop anytime.

Each test includes:

Proper imports for detected framework
Setup/teardown (DB connection, cleanup)
Comprehensive coverage:
- Success cases (happy path)
- Validation errors (400)
- Not found (404)
- Auth failures (401/403) if protected
- Edge cases (duplicates, empty, null)

Reference: See test-patterns.md for complete code examples.

Phase 3: Report

Generated: X test files
Coverage: Y test cases total
Next: Run `npm test` to verify

</workflow> <quick-reference>

Quick Reference

File Type	Imports	DB Setup
Route	`supertest` , `mongodb-memory-server`	Real (in-memory)
Service	`jest`	Mocked
Model	`mongoose`	Mocked
Middleware	`jest`	None

Test Structure Pattern

describe('[Resource] [Method]', () => {
  describe('success cases', () => {
    it('should [expected behavior]', async () => {});
  });
  describe('validation errors', () => {
    it('should return 400 for [invalid case]', async () => {});
  });
  describe('edge cases', () => {
    it('should handle [edge case]', async () => {});
  });
});

</quick-reference> <checklists>

Checklists

Infrastructure (Check First)

Test framework in
```
package.json
```
Test script defined (
```
"test": "jest"
```
)
Supertest installed (integration tests)
mongodb-memory-server installed (DB tests)

Per-File Generation

</checklists> <common-mistakes>

Common Mistakes

Mistake	Fix
Starting server in tests	Import app, let Supertest handle it
No DB cleanup	Add `afterEach` with `deleteMany({})`
Testing implementation	Test behavior through HTTP interface
Missing async/await	Await async operations
Mocking in integration tests	Use real DB for integration

</common-mistakes> <guidelines>

Guidelines

Don't generate tests for unread code
Don't skip infrastructure check
Don't generate only happy paths
Don't forget cleanup between tests

</guidelines> <references>

Reference Files

Load when implementing specific patterns:

When	Reference
Writing any test	test-patterns.md
Setting up test infrastructure	test-setup.md

</references>