Spec has no expectations - Jasmine testing the callback function

user_7509513 0
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I have a method which is being called using a d3 timer. Whenever the method is called, the method emits an object with a couple of values. One of the values increases over time. I would like to write a test to check whether the values are in the ascending order or not (i.e., increasing over time or not).

So, to tackle this, In my test, I subscribe to the event emitter and inside the subscription, I am pushing the object which I receive into a local array. And then, I am expecting the array[i] to be less than the array[i+1]. I think my logic is perfectly correct but I am not sure why I am getting an error from Jasmine saying that the spec has no expectations even though I have one.

Here is the code:

let x = d3.timer((elapsed) => { 
    this.method(); // call the function
    if(elapsed >= 500) {
     x.stop(); // stops the timer.
    }
});

method(elapsed) {
 // do something
 if(elapsed > 500) {
   this.output.emit({x: somevalue, y: somevalue, f: increasingvalue });
 }
}

The Jasmine Spec:

it('my spec', inject([JumpService], (service: JumpService) =>{
  array = [];
  //service calls the method
  service.output.subscribe(e => {
   array.push(e);
   // A console statement here will give me the length and the object pushed.
   for(let i = 0; i< array.length - 1; i++) {
    expect(array[i].f).toBeLessThan(array[i+1].f);
   }

  });

}));

Am I doing anything wrong here? How can I tackle such kind of a scenario? Please guide me in a right direction.

Thank you.

jasmine2.0 jasmine angular typescript javascript
4 Answers

Try using async function from @angular/core/testing. It

Wraps a test function in an asynchronous test zone. The test will automatically complete when all asynchronous calls within this zone are done. Can be used to wrap an {@link inject} call.

Please find code example below:

it('...', async(inject([AClass], (object) => {
  object.doSomething.then(() => {
   expect(...);
  })
});
user_13700290

I was successful in using waitForAsync to wrap my it function in.

it('should display correct data', waitForAsync(() => {

    fixture.whenStable().then(() => {
      // expect 
    });
 }));
user_85637050

You should use done() at the end of the promise, but from Jasmine 2.8.0 that will not work because there is not implementation for a done() method. You should test your promises like:

it('does test promise',
    inject([MyService], async (myService: MyService) => {
        const result = await myService.serviceToTest()
        expect(result).not.toBeNull()
        expect(result).toBe('Some Value')
     })
)

Hope that this help you

user_106489870
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