chai-subset

"containSubset" object properties matcher for Chai assertion library

Installation

npm install --save-dev chai-subset

Usage

common.js

1var chai = require('chai');
2var chaiSubset = require('chai-subset');
3chai.use(chaiSubset);

in your spec.js

1var obj = {
2	a: 'b',
3	c: 'd',
4	e: {
5		foo: 'bar',
6		baz: {
7			qux: 'quux'
8		}
9	}
10};
11	
12expect(obj).to.containSubset({
13	a: 'b',
14	e: {
15		baz: {
16			qux: 'quux'
17		}
18	}
19});
20
21// or using a compare function
22expect(obj).containSubset({
23	a: (expectedValue) => expectedValue,
24	c: (expectedValue) => expectedValue === 'd'
25})
26
27// or with 'not'
28expect(obj).to.not.containSubset({
29	g: 'whatever'
30});

Also works good with arrays and should interface

1var list = [{a: 'a', b: 'b'}, {v: 'f', d: {z: 'g'}}];
2
3list.should.containSubset([{a:'a'}]); //Assertion error is not thrown
4list.should.containSubset([{a:'a',  b: 'b'}]); //Assertion error is not thrown
5
6list.should.containSubset([{a:'a', b: 'bd'}]); 
7/*throws
8AssertionError: expected
9[
10    {
11        "a": "a",
12        "b": "b"
13    },
14    {
15        "v": "f",
16        "d": {
17            "z": "g"
18        }
19    }
20]
21to contain subset 
22[ { a: 'a', b: 'bd' } ]
23*/

and with assert interface

1assert.containSubset({a: 1, b: 2}, {a: 1});