Jasmine toEqual for complex objects (mixed with functions)

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();
});