Nestjs testing
Skill dkmqflx/nestjs-best-practices-plugin/plugins/nestjs-best-practices/skills/nestjs-testing
NestJS testing best practices (unit and e2e). Use when writing or reviewing NestJS tests — Test.createTestingModule, mocking providers, controller/service unit tests, or e2e with supertest. Triggers on TestingModule, createTestingModule, overrideProvider, or supertest.From its SKILL.md
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SKILL.md
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NestJS Testing
Best practices for testing NestJS applications, following the official testing docs
(https://docs.nestjs.com/fundamentals/testing). Covers isolated unit tests built with
Test.createTestingModule and full-stack e2e tests driven through supertest. Each rule
pairs an antipattern with the idiomatic Jest pattern.
When to Apply
Reference these guidelines when:
- Writing unit tests for a controller or service with
Test.createTestingModule - Mocking a unit's dependencies (repositories, HTTP clients, other services)
- Writing e2e tests that hit the real HTTP server via supertest
- Bypassing guards/auth or swapping providers in e2e
- Managing test data, fixtures, and teardown between tests
- Reviewing or refactoring an existing NestJS test suite
Rules
test-createtestingmodule(CRITICAL) — build the unit under test withTest.createTestingModule(...).compile()mock-dependencies(CRITICAL) — provide mock providers (useValue) for every dependency of the unitunit-test-services(HIGH) — test service logic against mocked repos/clients, never a real DBe2e-with-supertest(HIGH) — exercise the whole app over HTTP withcreateNestApplication+ supertestoverride-guards-in-e2e(HIGH) — bypass auth in e2e withoverrideGuard/overrideProviderisolated-test-data(HIGH) — fresh fixtures per test; reset mocks and tear down the app/DB between teststest-behavior-not-implementation(MEDIUM) — assert returned values and HTTP contracts, not internal call shapes
How to Use
Read the individual rule file for the explanation and before/after example:
rules/test-createtestingmodule.md
rules/mock-dependencies.md
rules/unit-test-services.md
rules/e2e-with-supertest.md
rules/override-guards-in-e2e.md
rules/isolated-test-data.md
rules/test-behavior-not-implementation.md
Each rule file contains:
- A short explanation of why it matters, tied to the official docs
- An Incorrect example (the antipattern)
- A Correct example (the idiomatic NestJS + Jest pattern)
All examples target NestJS v10/v11 with the @nestjs/testing package and supertest.
What ships with it: 7 files
11.8 KB alongside SKILL.md