node-shared

Service provider for Node.JS without pain with Dependency Injection Container, dependency registration, and configuration.

• You can use it at any place of your application without rewrite your applications architecture or other preparations or initializations.
• Each dependency can be class or function.
• You can override your dependencies for unit testing without hack standard Node.JS require mechanism.
• You can use TypeScript or JavaScript.

Examples

import { shared } from "node-shared";

// It is can be service or shared state or cross requests data
class Users {
  async getById(id) {
    ...
  }
}

const sharedUsers = () => shared(Users);

// And with express for example
app.get("/user/:id", async (req, res) => {
  const users = sharedUsers();
  res.json(await users.getById(req.params.id));
});

And

import { shared } from "node-shared";
// ...

class Db { /* ... */ }
class Server { /* ... */ }
// ...

// Inject dependencies using a shared function and class properties
export default class App {
  db = shared(Db);
  server = shared(Server);
  // ...
  start() {
    this.db.init();
    // ...
  }
}

// index.ts
new App().start(); // You can create an instance directly as usually class

Unit testing

You can use mock to provide mocks into your dependencies.

import { mock } from "node-shared";
import { Users, Api } from "./shareds";

test("Users service should call api service inside", async () => {
  const apiMock = mock(Api, {
    getUserById: jest.fn();
  });

  const users = new Users();

  await users.getById("John");
  expect(apiMock.getUserById).toHaveBeenCalledWith("John");
});

If you use Jest for unit testing you need to add some code to your jest.config.json file.

// jest.config.json
{
  ...
  setupFilesAfterEnv: [
    "node-shared/jest"
  ],
  ...
}

This code means that after each test cached shareds instances will be clear. For another testing frameworks, you need call free after each test case manually for cleanup cached instances of dependencies.

afterEach(require("node-shared").free);

API Reference

shared

Returns instance of your dependency. Each dependency can be class or function.

• For class. The class will be instantiated once and cached
• For function. The function will be called and result cached

const db = shared(Db);

mock

Define resolved value for any dependency.

const mockedDb = mock(Db, {
  connect: jest.fn()
});

shared(Db).connect();
expect(mockedDb.connect).toHaveBeenCalled();

free

Clean all cached shared instances. It's needed for testing usually. Has no parameters.

free()

Install

npm i node-shared

Enjoy and Happy Coding!