How to spyOn a static class method with Jasmine

javascript class static jasmine spy
Sherman Hui picture Sherman Hui · Jan 31, 2017 · Viewed 18.1k times · Source

I have a class with a static method that I want to test in Jasmine. I understand that static methods are not callable on instances of the class. So besides the fact that it cannot find the method to spyOn, my test does not pass, but how would one go about testing static methods in a class with Jasmine?

class Foo {
    static foobar (a, b) {
      return a * b
    }
}

Jasmine Test

it ('should test a static method', () => {
    let foo = new Foo()
    spyOn(foo, 'foobar')
    foo.foobar(2,3)
    expect(foo.foobar).toBe(6)
})

Answer

Daniel A. White picture Daniel A. White · Jan 31, 2017

You should be able to use spyOn(Foo, 'foobar') to make it a spy.

Also spies are not intended to directly be tested - they are a tool so that you can test other code more deterministically and in isolation.

Related questions

TypeScript static classes

I wanted to move to TypeScript from traditional JS because I like the C#-like syntax. My problem is that I can't find out how to declare static classes in TypeScript. In C#, I often use static classes to organize …

Read More
Call static methods from regular ES6 class methods

What's the standard way to call static methods? I can think of using constructor or using the name of the class itself, I don't like the latter since it doesn't feel necessary. Is the former the recommended way, or is …

Read More
js call static method from class

I have a class with a static method: class User { constructor() { User.staticMethod(); } static staticMethod() {} } Is there something like this so for static methods (i.e. refer to the current class without an instance). this.staticMethod() so I don't have …

Read More