Deep Object Equality of only own Object's Properties in Chai

Question

I have an object that I would like to do a deep comparison against another object in chaijs. The trouble is that one object has a large number of enumerable properties and the other object is a simple, straightforward object ({}).

For example, I have expect(obj1).to.eql(obj2); where obj1 is an object with many additional enumerable properties that a library added and obj2 was simply created via var obj2 = { someValue: true }.

This problem can be solved by abusing JSON.stringify and JSON.parse like so

expect(JSON.parse(JSON.stringify(obj1))).to.eql(obj2);

but that is a pretty lame hack. I can't image that I am the first one to run into this predicament but my searches have turned up empty. What is the recommended approach here?

Answer 1

You can try to use chai-shallow-deep-equal. It does not perform full equality check, but check that second object contains set of properties of first object.

Here's usage example:

var chai = require('chai');
chai.use(require('chai-shallow-deep-equal'));

var obj1 = {name: 'Michel', language: 'javascript'};
var obj2 = {name: 'Michel'};
var obj3 = {name: 'Michel', age: 43};

expect(obj1).to.shallowDeepEqual(obj2); // true
expect(obj1).to.shallowDeepEqual(obj3); // false, age is undefined in obj1