Testing

@blixis-io/testing builds a real application — real DI container, real router, real validation — in a test, with two conveniences on top: swapping specific providers for fakes, and a request() helper that skips building Request/URL objects by hand.

Test.createModule().compile()

import { Test } from "@blixis-io/testing";

const app = await Test.createModule({ imports: [PostsModule] }).compile();

const res = await app.request("/posts");
expect(res.status).toBe(200);

await app.close();

createModule() takes the same shape as @Module({...}) — imports, providers, controllers — and wraps it in a synthetic root module. compile() builds a full HttpApplication from it, exactly the way createHttpApplication would in production (see Routing & Controllers); nothing about request handling, validation, or guards is mocked.

.override()

Replace one provider with a fake before the module graph resolves:

const fakeRepo = { findAll: () => ["fake-1"] };

const app = await Test.createModule({ imports: [PostsModule] })
  .override(PostRepository, { useValue: fakeRepo })
  .compile();

The second argument is any provider shape minus provide ({ useValue }, { useClass }, { useFactory, inject? }, or { useExisting }) — see Dependency Injection. .override() is chainable and can be called more than once for different tokens. Overriding a token nothing in the graph actually uses is a silent no-op, not an error — worth double-checking the token matches if an override doesn’t seem to take effect.

.request()

const res = await app.request("/posts", {
  method: "POST",
  json: { title: "hi" },
});

This is sugar over app.handle(new Request(...)) — no socket involved, so tests run fast and don’t need to manage a port. path is resolved against http://localhost, so a bare path like /posts just works. The json option JSON-stringifies its value into the body and sets content-type: application/json automatically; anything else Request’s own init accepts (method, headers, a raw body) passes straight through.

.get() and .close()

app.get(PostRepository); // the resolved instance — the fake, if you overrode it
await app.close();       // runs OnApplicationShutdown hooks

.get() is useful for asserting on injected state directly rather than only through HTTP responses — the override example above could confirm the swap with expect(app.get(PostRepository)).toBe(fakeRepo).

Next

• A full TDD walkthrough building a new endpoint: Test-Driven API Development.
• More detail on when and why to override: Overriding Providers in Tests.
• Every exported symbol: @blixis-io/testing reference.