Expressively-mocked-fetch NPM

expressively-mocked-fetch

A fetch mock that launches express as a worker_thread to help testing.

Installation

NOTE: This library uses worker_threads, a nodejs builtin that was released with node v13.

$ npm i -D expressively-mocked-fetch

Why

Mocking fetch is annoying. I saw msw. But it didn't fit my use case. So I ended up writing a wrapper around express.js.

Develop

Download this repo and install the dependencies
Run npm run test

Usage

// with ava
const test = require("ava");
const createWorker = require("expressively-mocked-fetch");

test("if module is loaded and executed", async (t) => {
  const worker = await createWorker(`
// regular express.js code
app.get('/', function (req, res) {
  res.send("hello world");
});
  `);

  const res = await fetch(`http://localhost:${worker.port}`);
  const text = await res.text();
  t.assert(test === "hello world");
});

createWorker(string, object)

string needs to be valid Node.js JavaScript
object is of shape { requestCount: Number, port: Number }, where:
- requestCount (optional, default: 1) is the amount of times a server should respond before automatically shutting itself.
- port (optional, default: 0) is the desired port the server should launch at. For dynamic allocation by the OS, use the default value 0.
- pauseMilliseconds (optional, default: 0) the time in milliseconds a server must delay sending an answer using connect-pause.

Changelog

0.2.3

Introduce optional option pauseMilliseconds that allows simulating a server's delayed response-ability.

0.2.2

Allow template's app to be overwritten by using let.

0.2.1

(Bug fix): options allows now to set individual keys without forgetting all default options.

0.2.0

Refactor createWorker function signature to allow an options object.
Add port to options that allows a user to define a port before launching a worker.

0.1.2

Using node.js's worker_threads now allows expressively-mocked-fetch to spawn threads without the usage of temporary files. Interface remains the same.