@tm1-oss/chai-subset

"containSubset" object properties matcher for Chai assertion library

Difference from the original package: Better error messages and contained arrays must contain identical objects in order

Installation
===========

npm install --save-dev @tm1-oss/chai-subset

Usage
=====

common.js
``js
var chai = require('chai');
var chaiSubset = require('@tm1-oss/chai-subset');
chai.use(chaiSubset);
`

in your spec.js
`js
var obj = {
a: 'b',
c: 'd',
e: {
foo: 'bar',
baz: {
qux: 'quux'
}
},
f: [ { g: 'h' }, { i: 'j' } ]
};

expect(obj).to.containSubset({
a: 'b',
e: {
baz: {
qux: 'quux'
}
}
});

// Assertion error IS NOT thrown
expect(obj).to.containSubset({
f: [ { g: 'h' }, { i: 'j' } ]
});

// Assertion error IS thrown as the contained array is not identical to the array in obj.
expect(obj).to.containSubset({
f: [ { i: 'j' } ]
});


// or using a compare function
expect(obj).containSubset({
a: (expectedValue) => expectedValue,
c: (expectedValue) => expectedValue === 'd'
})

// or with 'not'
expect(obj).to.not.containSubset({
g: 'whatever'
});
`

Also works good with arrays and should interface
`js
var list = [{a: 'a', b: 'b'}, {v: 'f', d: {z: 'g'}}];

list.should.containSubset([{a:'a'}]); //Assertion error is thrown
list.should.containSubset([{a:'a', b: 'b'}]); //Assertion error is thrown

list.should.containSubset([{a:'a', b: 'bd'}]);
/*throws
AssertionError: expected
[
{
"a": "a",
"b": "b"
},
{
"v": "f",
"d": {
"z": "g"
}
}
]
to contain subset
[ { a: 'a', b: 'bd' } ]
*/
`

and with assert interface
`js
assert.containSubset({a: 1, b: 2}, {a: 1});
``