object-sandbox

Save and restore definition of Nodejs objects to allow stubbing of properties, methods, getters, and setters during testing.

Usage

Sandbox objects

let obj1 = {
    method() { console.log('original'); }
};
let obj2 = {
    foo: 'bar'
};

const objectSandbox = require('object-sandbox');
let sandbox = objectSandbox.create(obj1, obj2);

Sandbox addtional objects

let obj3 = { another: 'object' };
sandbox.add(obj3);

Change object properties

obj1.method = () => console.log('stubbed');
obj2.foo = 'rab';

obj1.method(); // stubbed
obj2.foo === 'rab' // true

Restore all objects in the sandbox

sandbox.restore(); 

obj1.method(); // original
obj2.foo === 'bar' // true

This can be used to sandbox and restore objects with sinon stubbed getters and setters, as sinon doesn't support restoring getters (2.2.0), as it tries to run the getter while restoring, and sinon.sandbox doesn't support defining getters.

const sinon = require('sinon');
require('chai').should();

const objectSandbox = require('object-sandbox');

class MyClass {
    constructor() {
        this.event = 'no event';
    }
    get prop() {
        this.event = 'original getter run';
        return 'original value';
    }
    set prop(value) {
        this.event = 'original setter run: ' + value;
    }
}

describe('Sandboxed object', () => {
    let sandbox, instance;

    beforeEach( () => {
        sandbox = objectSandbox.create(MyClass.prototype);
        sinon.stub(MyClass.prototype, 'prop').get(function () {
            this.event = 'stubbed getter run';
            return 'test value';
        });
        instance = new MyClass;
    });

    afterEach( () => {
        sandbox.restore();
    });

    it('returns the stubbed getter', () => {
        instance.prop.should.equal('test value');
        instance.event.should.equal('stubbed getter run');
    });

    it('runs the original setter', () => {
        instance.prop = 'new value';
        instance.event.should.equal('original setter run: new value');
    });

    it('runs the original getter when restored', () => {
        sandbox.restore();
        instance.prop.should.equal('original value');
        instance.event.should.equal('original getter run');
    });

    it('does not run any getters or setters when restoring', () => {
        sandbox.restore();
        instance.event.should.equal('no event');
    });
});