testeves

A workaround testing strategy for highly coupled legacy codebase.

Why

Sometimes you need to test some legacy code which is not actually testable. Refactoring the codebase to write testable code may be hard or it doesn't worth.

How

It's important to learn how testeves works. It is a simple concept. You emit events at critical points in the codebase. The test agent will listen for these events and execute expectations.

Install

Requires Node >= 8.

From npm:

npm install @vaju/testeves

From Github Package Registry. (Guide).

(✔ Type definitions included for TypeScript)

Usage

The tests for this repo (inside the /tests dir) is an ideal example.

The code you need to test: foo.js

const { Testeves } = require('@vaju/testeves');
// or
import { Testeves } from '@vaju/testeves';

// create a hook
const hook = new Testeves();

// ... somewhere in the actual codebase we want to test ...

function foo() {
  ['a', 'b', 'c'].forEach(item => {
    // emit events
    hook.emit({ [item]: true });
  });
  // when the flow is complete, call finishProcess().
  return hook.finishProcess();
}

module.exports = { foo, hook };

Then the test file: foo.spec.js

const { foo, hook } = require('./foo');

// Start the observer. Here is where
// the emitted events are stored.
const observer = hook.listen();

// Before running into actual tests, wait for
// the entire flow to complete.
beforeAll(() => {
  // invoke the function.
  foo();
  // hook.isFinished returns a promise, which is
  // resolved when the hook.finishProcess() is called
  // in the testing code.
  return hook.isFinished;
});

describe('testing', () => {
  test('testing a', () => {
    // the observer object stores the emitted
    // events and their values.
    expect(observer.a).toBe(true);
  });
  test('testing b', () => {
    expect(observer.b).toBe(true);
  });
  test('testing c', () => {
    expect(observer.c).toBe(true);
  });
});

Licence

MIT © Vajahath Ahmed