The testing package provides utilities for unit and integration testing of nestelia applications.

Quick Start

import { describe, expect, it, beforeAll } from "bun:test";
import { Injectable } from "nestelia";
import { Test, TestingModule } from "nestelia/testing";

@Injectable()
class UserService {
  getUsers() {
    return [{ id: 1, name: "John" }];
  }
}

describe("UserService", () => {
  let module: TestingModule;
  let userService: UserService;

  beforeAll(async () => {
    module = await Test.createTestingModule({
      providers: [UserService],
    }).compile();

    userService = module.get(UserService);
  });

  it("should return users", () => {
    expect(userService.getUsers()).toEqual([{ id: 1, name: "John" }]);
  });
});

Mocking Dependencies

Override with Value

const mockDb = {
  query: () => [{ id: 1, name: "Mock User" }],
};

const module = await Test.createTestingModule({
  providers: [UserService, DatabaseService],
})
  .overrideProvider(DatabaseService)
  .useValue(mockDb)
  .compile();

Override with Class

class MockDatabaseService {
  query() {
    return [{ id: 1, name: "Mock" }];
  }
}

const module = await Test.createTestingModule({
  providers: [UserService, DatabaseService],
})
  .overrideProvider(DatabaseService)
  .useClass(MockDatabaseService)
  .compile();

Override with Factory

const module = await Test.createTestingModule({
  providers: [UserService, DatabaseService],
})
  .overrideProvider(DatabaseService)
  .useFactory(() => ({
    query: () => [{ id: 1, name: "Factory Mock" }],
  }))
  .compile();

API Reference

Test.createTestingModule(metadata)

Creates a TestingModuleBuilder.

Parameters:

• metadata — Module configuration (providers, imports, controllers)

TestingModuleBuilder

Method	Description
.overrideProvider(token)	Start overriding a provider
.useValue(value)	Replace with a static value
.useClass(metatype)	Replace with a different class
.useFactory(factory, inject?)	Replace with a factory function
.compile()	Build and return a Promise<TestingModule>

TestingModule

Method	Description
.get<T>(token)	Get a provider instance (synchronous)
.resolve<T>(token)	Resolve a provider (async, for request-scoped)
.has(token)	Check if a provider is registered