@blixis-io/testing

Build a real application in a test, optionally with fakes swapped in, and hit it with real requests. See Testing for the concepts.

Test.createModule(metadata).compile(options?)

const Test: {
  createModule(metadata?: ModuleMetadata): TestModuleBuilder;
};

class TestModuleBuilder {
  override<T>(token: Token<T>, definition: OverrideDefinition<T>): this;
  compile(options?: Omit<HttpApplicationOptions, "overrides">): Promise<TestApplication>;
}

type OverrideDefinition<T> =
  | Omit<ClassProvider<T>, "provide">
  | Omit<ValueProvider<T>, "provide">
  | Omit<FactoryProvider<T>, "provide">
  | Omit<ExistingProvider<T>, "provide">;

createModule(metadata) takes the same shape as @Module({...}) (imports/providers/controllers — see @blixis-io/core reference) and wraps it in a synthetic root module internally. .override(token, definition) is chainable and queues a provider replacement, applied before the module graph resolves — definition is any provider shape minus provide (see @blixis-io/di reference). .compile(options?) builds the real HttpApplication (accepting the same bodyLimit option as createHttpApplication — see @blixis-io/http reference — but not overrides, since that’s what .override() is for) and returns a TestApplication.

TestApplication

class TestApplication {
  constructor(app: HttpApplication);
  request(path: string, init?: TestRequestInit): Promise<Response>;
  get<T>(token: Token<T>): T;
  close(signal?: string): Promise<void>;
}

interface TestRequestInit extends Omit<RequestInit, "body"> {
  body?: RequestInit["body"];
  json?: unknown; // JSON-stringified into the body, sets content-type: application/json automatically
}

Thin sugar over a real HttpApplication (see @blixis-io/http reference) — request() resolves path against http://localhost and builds the Request for you, so app.request("/posts") works without constructing a URL by hand. get() and close() pass straight through to the underlying HttpApplication.

TestApplication’s constructor is public — you can wrap an HttpApplication you built another way (say, one from createHttpApplication directly) to get the request() helper without going through Test.createModule() at all.