stub.js

// This is a hack for stubbing functions with arguments in jasmine2

function With(stub, values) {
  this.stub = stub;
  this.values = values;
}

With.prototype.andReturn = function (returnValue) {
  this.stub.addStubbedCall(this.values, returnValue);
};

function Stub() {
  this.stubbedCalls = [];
}

Stub.prototype.with = function () {
  var values = [];
  for (var _i = 0; _i < arguments.length; _i++) {
    values[_i - 0] = arguments[_i];
  }
  return new With(this, values);
};

Stub.prototype.addStubbedCall = function (values, returnValue) {
  this.stubbedCalls.push({ values: values, returnValue: returnValue });
};

Stub.prototype.andReturn = function (returnValue) {
  this.addStubbedCall([], returnValue);
};

Stub.prototype.getStubbedReturnValue = function (values) {
  var stubbedCall = _.find(this.stubbedCalls, function (value) { return _.isEqual(value.values, values); });
  return stubbedCall && stubbedCall.returnValue;
};

function stub(object, functionName) {
  var stub = new Stub();
  if (!object[functionName].calls) {
    spyOn(object, functionName).and.callFake(function fake() {
      var values = [];
      for (var _i = 0; _i < arguments.length; _i++) {
        values[_i - 0] = arguments[_i];
      }
      return stub.getStubbedReturnValue(values);
    });
  }
  return stub;
}

// example usage

let x = {add: function(x, y) {}};
stub(x, 'add').with(1, 2).andReturn(3);
stub(x, 'add').with(2, 3).andReturn(5);
console.log(x.add(1, 2));  // logs 3
console.log(x.add(2, 3));  // logs 5