JS - Mocking an uninitialized class method inside a function-CodePudding

Lets say I have this code below and I want to test someFunc() but I want to mock the doSomething() function? How can I do it in a test when the SomeClass is initialized only inside the someFunc() itself and not in the test?

class SomeClass {
  constructor(element){
    this.element = element
  }
  
  doSomething(element){
    ...
  }
}

function someFunc() {
  const newClass = new SomeClass()
  newClass.doSomething() // I want this to get to the mocked function
}

I am using jest, please help!

CodePudding user response：

Try some testing frameworks, most of them provide spies which allow you to mock specific functions for given classes.

For example, you can try Jasmine - https://jasmine.github.io/api/edge/Spy.html Where you would do something like

spyOn(newClass, 'doSomething').and.returnValue(42);

CodePudding user response：

There are multiple ways to mock es6 class in Jest: https://jestjs.io/docs/es6-class-mocks