backend-template/packages/web-api/test/index.test.ts

import { FastifyInstance } from 'fastify';
import {
	describe,
	it,
	expect,
	beforeAll,
	afterAll,
	vi,
} from 'vitest';
import { constants } from 'http2';
import { createServer } from '../src/server';
import { addRoutes } from '../src/routes';
import {
	AdderServiceImpl,
	ArgumentOutOfRangeError,
	InvalidArgumentTypeError,
} from '../src/modules/adder';

describe('Example', () => {
	let server: FastifyInstance;
	const body = { a: 1, b: 2 };

	beforeAll(() => {
		server = createServer();
		addRoutes(server);
	});

	afterAll(async () => {
		await server.close();
	});

  it('returns result when successful', async () => {
    const response = await server
      .inject()
      .post('/')
			.body(body)
      .headers({
        'Accept': 'application/json',
      });
    expect(response.statusCode).toBe(constants.HTTP_STATUS_OK);
  });

	it('returns error when given invalid inputs', async () => {
		vi.spyOn(AdderServiceImpl.prototype, 'addNumbers').mockImplementationOnce(() => {
			throw new InvalidArgumentTypeError('Invalid input');
		});

		const response = await server
			.inject()
			.post('/')
			.body(body)
			.headers({
				'Accept': 'application/json',
			});
		expect(response.statusCode).toBe(constants.HTTP_STATUS_BAD_REQUEST);
	});

	it('returns error when given out-of-range inputs', async () => {
		vi.spyOn(AdderServiceImpl.prototype, 'addNumbers').mockImplementationOnce(() => {
			throw new ArgumentOutOfRangeError('Out of range');
		});

		const response = await server
			.inject()
			.post('/')
			.body(body)
			.headers({
				'Accept': 'application/json',
			});
		expect(response.statusCode).toBe(constants.HTTP_STATUS_BAD_REQUEST);
	});

	it('returns error when an unexpected error occurs', async () => {
		vi.spyOn(AdderServiceImpl.prototype, 'addNumbers').mockImplementationOnce(() => {
			throw new Error('Unexpected error');
		});

		const response = await server
			.inject()
			.post('/')
			.body({ a: 1, b: 2 })
			.headers({
				'Accept': 'application/json',
			});
		expect(response.statusCode).toBe(constants.HTTP_STATUS_INTERNAL_SERVER_ERROR);
	});
});