Test MongoDB Repository

Write Vitest tests for MongoDB repository implementations. Requires test infrastructure setup with mongodb-memory-server.

Quick Reference

Location: tests/repositories/{entity-name}.mongodb.repository.test.ts Run tests: pnpm test -- tests/repositories/{entity-name}.mongodb.repository.test.ts

Prerequisites

1. Install Dependencies

pnpm add -D mongodb-memory-server

2. Configure Vitest

Update vitest.config.ts:

export default defineConfig({
  test: {
    include: ["tests/**/*.test.ts"],
    globalSetup: ["./tests/config/mongodb.global.ts"],
    setupFiles: ["./tests/config/mongodb.setup.ts"],
    pool: "forks", // Avoid database conflicts
    // ... other config
  },
});

3. Create Test Config Files

You need two configuration files. See REFERENCE.md for complete files:

• tests/config/mongodb.global.ts - Starts/stops MongoDB Memory Server
• tests/config/mongodb.setup.ts - Mocks database connection, provides test helpers

Test Structure

import {
  describe,
  it,
  expect,
  beforeEach,
  afterEach,
  beforeAll,
  afterAll,
} from "vitest";
import { MongoDb{Entity}Repository } from "@/repositories/mongodb/{entity-name}.mongodb.repository";
import type { MongoClient, Db } from "mongodb";
import type {
  Create{Entity}Type,
  Update{Entity}Type,
  {Entity}QueryParamsType,
} from "@/schemas/{entity-name}.schema";

describe("MongoDb{Entity}Repository", () => {
  let repository: MongoDb{Entity}Repository;
  let testClient: MongoClient;
  let testDb: Db;
  const testUserId = "test-user-123";

  beforeAll(async () => {
    // Global helper from mongodb.setup.ts
    const { db, client } = await setupTestDatabase();
    testDb = db;
    testClient = client;
  });

  afterAll(async () => {
    await cleanupTestDatabase(testClient);
  });

  beforeEach(async () => {
    repository = new MongoDb{Entity}Repository();
    await repository.clear();
  });

  afterEach(async () => {
    await repository.clear();
  });

  // Test cases...
});

Test Cases

CRUD Operations

Same patterns as MockDB tests. See test-mockdb-repository skill for:

• create
• findById
• findAll (with filtering, pagination, sorting)
• update
• remove

MongoDB-Specific: Data Validation

describe("data validation", () => {
  it("validates data using Zod schema when mapping from document", async () => {
    const data: Create{Entity}Type = { content: "Valid content" };
    const result = await repository.create(data, testUserId);

    // Zod validation ensures proper types
    expect(result.id).toBeTruthy();
    expect(result.createdAt).toBeInstanceOf(Date);
    expect(result.updatedAt).toBeInstanceOf(Date);
  });
});

MongoDB-Specific: Database Indexes

describe("database indexes", () => {
  it("creates proper indexes for performance", async () => {
    // Create entity to trigger collection initialization
    await repository.create({ content: "Test" }, testUserId);
    const stats = await repository.getStats();

    expect(stats.indexes).toContain("_id_");
    expect(stats.indexes).toContain("{entities}_createdBy");
    expect(stats.indexes).toContain("{entities}_createdAt_desc");
    expect(stats.indexes).toContain("{entities}_{field}_text");
  });
});

MongoDB-Specific: Helper Methods

describe("helper methods", () => {
  beforeEach(async () => {
    await repository.create({ content: "Test 1" }, testUserId);
    await repository.create({ content: "Test 2" }, testUserId);
  });

  it("clears all entities", async () => {
    await repository.clear();
    const result = await repository.findAll({});
    expect(result.data).toHaveLength(0);
  });

  it("returns collection stats", async () => {
    const stats = await repository.getStats();
    expect(stats.count).toBe(2);
    expect(stats.indexes).toEqual(expect.any(Array));
  });
});

What to Test

Test Infrastructure Explained

vitest.config.ts

mongodb.global.ts

• Starts mongodb-memory-server once for entire test run
• Stores URI and database name in process.env
• Tears down when all tests complete

mongodb.setup.ts

• Mocks @/config/mongodb.setup module
• Provides global setupTestDatabase() and cleanupTestDatabase() helpers
• Redirects repository database calls to the in-memory server

Complete Example

See REFERENCE.md for:

• Complete MongoDB repository test file
• vitest.config.ts configuration
• tests/config/mongodb.global.ts
• tests/config/mongodb.setup.ts

What NOT to Do

• Do NOT forget to set up the test infrastructure files
• Do NOT run MongoDB tests in parallel (use pool: "forks")
• Do NOT forget beforeAll/afterAll for database setup/teardown
• Do NOT forget to call repository.clear() in beforeEach/afterEach
• Do NOT skip index tests - they verify performance optimization