NestJS Test Suite Builder

The goal of this library is to eliminate the necessity of duplicating setup and teardown procedures in your tests. During the development process, I found that utilizing a custom test runner greatly enhanced the API. However, I prefer to wait for native support of top-level async/await in Jest to avoid potential issues or incompatibilities that may arise in the future.

Getting Started

yarn add nestjs-tsb

Create a fixture

A fixture serves as a container for your shared configuration. Additionally, you can utilize Jest hooks within the fixture to execute top-level operations. However, please keep in mind the behavior of Jest's describe grouping when working with fixtures.

class MyFixture extends TestFixture {
  public constructor() {
    super({
      providers: [MyFakeService, Gateway],
    });
  }

  public override configureProviders = (
    builder: ITestingModuleBuilder): VoidType => 
      builder
        .overrideProvider(Gateway)
        .useClass(FakeGateway);
}

Setup your Test Suite

const myFixture = new MyFixture();
const suite = new TestSuiteBuilder(myFixture).compile();

describe("test suite should", () => {
  test("include the dependencies from the fixture", async () => {
    const service = suite.getProvider(MyFakeService);

    expect(service).toBeDefined();
    expect(service).toBeInstanceOf(MyFakeService);
  });
});

Customize your current Fixture

Please be aware that by using this approach, your other configuration will be overridden.

class CustomizedFixture extends MyFixture {
  public override configureProviders = (
    builder: ITestingModuleBuilder): VoidType => 
      builder
        .overrideProvider(Gateway)
        .useClass(NewGateway);
}

Upcoming Features

The APIs displayed here are not yet finalized; they are provided for contextual purposes.

TestContext extensions

Add metadata to your test context.

Customize your current Fixture through the builder

const myFixture = new MyFixture();
const suite = new TestSuiteBuilder(myFixture)
  .subsitute(Gateway, NewGateway)
  .compile();

Get your overrides from the suite directly

const newGateway = suite.get('gateway')
// or with some magic
const newGateway = suite.newGateway