Why this if statement is not covered in jasmin-karma-istanbul report

Question

So here is curious case of a statement not getting covered by jasmin karma test runner, here is the function under testing

aFunction(fewParams) {
   
    if (fewCondition) {
    
      let elements = document.querySelectorAll(`[id^=${aParam}]`);
      let anElement = find(elements, (el) => el.classList.contains('a-class-name'));
      if (anElement) {
         /* rest of the logic */
      }
      if (updatedConditions) {
        /*rest of the logic*/
      }
    }
  }

and here is the test

 describe('aFunction', () => {
    it('it should do aFunctionality', () => {
      spyOn(document, "querySelectorAll").and.callFake(function() {
        return {
              value: true,
              classList: {
                remove: () => {},
                add: () => {},
                contains: () => { return ["a-class-name"] }
              }   
          }
      });
      componentInstance.aFunction("test", 1, true);
      expect(componentInstance.something).toBe(soemthing);
    });
  });

So the issue is here the

if (anElement) { 

}

statement is not getting covered even if the mock function for querySelectorAll is returning a classlist with required value.

Can you please help me with this?

Answer 1

If you spy on an element it looks like it is swallowing any runtime errors.

This is quite similar to the last issue, where add and remove was undefined. This time the problem is, that you are mocking the querySelectorAll method, which would need to return an array, so that the find method will be defined. You are returning an object and the find method does not exists on an object.

You would need to return something like this:

spyOn(document, "querySelectorAll").and.callFake(function() {
        return [{ // note the array here
              value: true,
              classList: {
                remove: () => {},
                add: () => {},
                contains: () => { return ["a-class-name"] }
              }   
          }]
      });