Exploring the world of Jasmine spyOn and mastering the art of utilizing spies in software

Question

Exploring the world of Jasmine spyOn and mastering the art of utilizing spies in software

I am new to JS unit testing and finding it challenging to understand how to effectively make use of Jasmine spies for creating meaningful tests.

it('should accept an array of shopping items', function() {
  spyOn(checkObj, 'getTotal');
  checkObj.getTotal([1, 2, 3]);
  expect(checkObj.getTotal).toHaveBeenCalledWith(jasmine.any(Array));
});

The test example above raises a concern regarding the hardcoded call to getTotal within the spec. While I want to ensure that the parameter passed is indeed an array and not another data type, I believe hardcoding in this manner could be problematic.

I would greatly appreciate some guidance on approaching this particular testing scenario effectively.

javascript unit-testing jasmine spyon

Answer 1

Answer №1

Spies play a crucial role in specific testing scenarios, particularly when defining the scope of unit tests. Consider a situation where you focus on the minimal unit of code, such as a method:

var x = function() { }
x.prototype.f1 = function() { 
        //do something 
};

x.prototype.f2 = function(){
          // do something else
          this.f1();
};

When testing function f2, you may not be concerned with the internal workings of f1. In this case, you can create a spy:

var a = new x();
a.f1 = jasmine.createSpy("spy-on-f1");
expect(a.f1).not.toHaveBeenCalled();
a.f2();
expect(a.f1).toHaveBeenCalled();

In AngularJS applications, it's common to use spies to mock entire services for algorithm isolation during testing.

Additionally, you have the option to replace actual function calls with fake functions like so:

a.f1 = jasmine.createSpy("fake-spy").and.callFake(function(){
    // perform a predictable action or return a globally set variable
});

Answer 2

Spies play a crucial role in specific testing scenarios, particularly when defining the scope of unit tests. Consider a situation where you focus on the minimal unit of code, such as a method:

var x = function() { }
x.prototype.f1 = function() { 
        //do something 
};

x.prototype.f2 = function(){
          // do something else
          this.f1();
};

When testing function f2, you may not be concerned with the internal workings of f1. In this case, you can create a spy:

var a = new x();
a.f1 = jasmine.createSpy("spy-on-f1");
expect(a.f1).not.toHaveBeenCalled();
a.f2();
expect(a.f1).toHaveBeenCalled();

In AngularJS applications, it's common to use spies to mock entire services for algorithm isolation during testing.

Additionally, you have the option to replace actual function calls with fake functions like so:

a.f1 = jasmine.createSpy("fake-spy").and.callFake(function(){
    // perform a predictable action or return a globally set variable
});

Exploring the world of Jasmine spyOn and mastering the art of utilizing spies in software

Answer №1

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