Checking the functionality of a feature with Jasmine framework in an Angular application

I am working on writing unit test cases and achieving code coverage for the code snippet below. Any advice on how to proceed?

itemClick($event: any) {
for (let obj of this.tocFiles) {
  let results = this.getchildren(obj, label);
  if (results) {
    console.log(results, 'results');
    this.clickedItem = results.children;
    break;
  }
}
}

 getchildren(obj: any, label: any) {
    if (obj.label == label) {
      return obj;
    }

    if (obj.children) {
      for (let item of obj.children) {
        let check: any = this.getchildren(item, label);
        if (check) {
          return check;
        }
      }
    }
    return null;
  }

Here is a sample test case that I have written,

it('When clicking on breadcrumb value, itemClick() should be called',()=>{ 
  const onClick = spyOn(component, 'itemClick'); 
  component.itemClick(undefined); 
  expect(onClick).toHaveBeenCalled(); 
});

However, I am facing difficulty in getting this code covered under code coverage.

Answer №1

By using the spyOn method, you can observe how a function is called and with what arguments, while losing sight of the internal workings of the function.

To strike a balance between monitoring function calls and retaining access to the implementation details, the .and.callThrough() method can be employed to actually execute the function and record its invocation details.

it('The itemClick() function should be invoked upon clicking a breadcrumb value', () => {
  // Add .and.callThrough() here 
  const onClick = spyOn(component, 'itemClick').and.callThrough(); 
  component.itemClick(undefined); 
  expect(onClick).toHaveBeenCalled(); 
});

However, it is worth noting that the test described above may not be optimal as it involves spying on a method, calling that method, and then expecting it to have been called.

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