Jasmine toEqual for complex objects (mixed with functions) - jasmine

Question

Currently, I have a function that sometimes return an object with some functions inside. When using expect(...).toEqual({...}) it doesn't seem to match those complex objects. Objects having functions or the File class (from input type file), it just can't. How to overcome this?

Answer 1

Try the Underscore _.isEqual() function:
expect(_.isEqual(obj1, obj2)).toEqual(true);
If that works, you could create a custom matcher:
this.addMatchers({
toDeepEqual: function(expected) {
return _.isEqual(this.actual, expected);
};
});
You can then write specs like the following:
expect(some_obj).toDeepEqual(expected_obj);

Answer 2

As Vlad Magdalin pointed out in the comments, making the object to a JSON string, it can be as deep as it is, and functions and File/FileList class. Of course, instead of toString() on the function, it could just be called 'Function'
function replacer(k, v) {
if (typeof v === 'function') {
v = v.toString();
} else if (window['File'] && v instanceof File) {
v = '[File]';
} else if (window['FileList'] && v instanceof FileList) {
v = '[FileList]';
}
return v;
}
beforeEach(function(){
this.addMatchers({
toBeJsonEqual: function(expected){
var one = JSON.stringify(this.actual, replacer).replace(/(\\t|\\n)/g,''),
two = JSON.stringify(expected, replacer).replace(/(\\t|\\n)/g,'');
return one === two;
}
});
});
expect(obj).toBeJsonEqual(obj2);

Answer 3

If anyone is using node.js like myself, the following method is what I use in my Jasmine tests when I am only concerned with comparing the simple properties while ignoring all functions. This method requires json-stable-stringify which is used to sort the object properties prior to serializing.
Usage:
var stringify = require('json-stable-stringify');
var obj1 = {
func: function() {
},
str1: 'str1 value',
str2: 'str2 value',
nest1: {
nest2: {
val1:'value 1',
val2:'value 2',
someOtherFunc: function() {
}
}
}
};
var obj2 = {
str2: 'str2 value',
str1: 'str1 value',
func: function() {
},
nest1: {
nest2: {
otherFunc: function() {
},
val2:'value 2',
val1:'value 1'
}
}
};
it('should compare object properties', function () {
expect(stringify(obj1)).toEqual(stringify(obj2));
});

Answer 4

Extending #Vlad Magdalin's answer, this worked in Jasmine 2:
http://jasmine.github.io/2.0/custom_matcher.html
beforeEach(function() {
jasmine.addMatchers({
toDeepEqual: function(util, customEqualityTesters) {
return {
compare: function(actual, expected) {
var result = {};
result.pass = _.isEqual(actual, expected);
return result;
}
}
}
});
});
If you're using Karma, put that in the startup callback:
callback: function() {
// Add custom Jasmine matchers.
beforeEach(function() {
jasmine.addMatchers({
toDeepEqual: function(util, customEqualityTesters) {
return {
compare: function(actual, expected) {
var result = {};
result.pass = _.isEqual(actual, expected);
return result;
}
}
}
});
});
window.__karma__.start();
});

Answer 5

here's how I did it using the Jasmine 2 syntax.
I created a customMatchers module in ../support/customMatchers.js (I like making modules).
"use strict";
/**
* Custom Jasmine matchers to make unit testing easier.
*/
module.exports = {
// compare two functions.
toBeTheSameFunctionAs: function(util, customEqualityTesters) {
let preProcess = function(func) {
return JSON.stringify(func.toString()).replace(/(\\t|\\n)/g,'');
};
return {
compare: function(actual, expected) {
return {
pass: (preProcess(actual) === preProcess(expected)),
message: 'The functions were not the same'
};
}
};
}
}
Which is then used in my test as follows:
"use strict";
let someExternalFunction = require('../../lib/someExternalFunction');
let thingBeingTested = require('../../lib/thingBeingTested');
let customMatchers = require('../support/customMatchers');
describe('myTests', function() {
beforeEach(function() {
jasmine.addMatchers(customMatchers);
let app = {
use: function() {}
};
spyOn(app, 'use');
thingBeingTested(app);
});
it('calls app.use with the correct function', function() {
expect(app.use.calls.count()).toBe(1);
expect(app.use.calls.argsFor(0)).toBeTheSameFunctionAs(someExternalFunction);
});
});

Answer 6

If you want to compare two objects but ignore their functions, you can use the methods _.isEqualWith together with _.isFunction from lodash as follows.
function ignoreFunctions(objValue, otherValue) {
if (_.isFunction(objValue) && _.isFunction(otherValue)) {
return true;
}
}
it('check object equality but ignore their functions', () => {
...
expect(_.isEqualWith(actualObject, expectedObject, ignoreFunctions)).toBeTrue();
});