Karma Jasmine Async Testing not working

Question

I'm currently trying to test something that uses async tasks, concrete I have the following lines:

setTimeout(function(){
 //do something
},300);

The setTimeout is in a function as well. Now in my test, I call this function, that contains the setTimeout and I'm getting an error, that the element I'm using inside of setTimeout is not defined/null.

Now I tried out various ways but none seems to work.

I tried to include done into my it and put the function call in a setTimeout, just like so:

setTimeout(function(){
  callTheFunctionThatContainsTheTimeout();
  done();
});

Doesn't work. I tried to import $timeout (I'm actually using angular), and then put the function call in $timeout and put a $timeout.flush afterwards, but nothing works. Does anybody know what I do wrong and how I can do it right?

Answer 1

I don't know if you really intended to call a function that contains the timeout from inside another timeout, but anyway this is feasible, if you are allowed to change the callTheFunctionThatContainsTheTimeout function.

The function would look something like:

function callTheFunctionThatContainsTheTimeout(callback) {
  setTimeout(function(){
    console.log('ooo'); // do something here
    callback(); // execute a callback function
  },300);
}

And the test would be like:

it('something to do', function(done){
  setTimeout(function(){
    callTheFunctionThatContainsTheTimeout(function(){ // the callback function
      expect(2+2).toEqual(4); // do your tests here
      done();
    });
  },200);
});

And if you do not need a second timeout, the test would look like:

it('something to do', function(done){
  callTheFunctionThatContainsTheTimeout(function(){ // the callback function
    expect(2+2).toEqual(4); // do your test here
    done();
  });
 });