Wrong type of error when testing javascript function

Question

I am trying to test the following code:

  /** ABSTRACT METHOD PLACEHOLDER */
MyResult.prototype.get = throwNotImplementedError;

function throwNotImplementedError(resultId) {
    throw new NotImplementedError('Please implement in Item Groups and Items. This call is abstract');
}

with the following test.

it('should have a placeholder for get', function(){
    expect(function(){return MyResult.get(123);}).toThrowError(NotImplementedError);
});

What ends up happenining is that a TypeError is thrown instead of my custom NotImplementedError. The type error's message is: "MyResult.get is not a function".

I'm wondering if it might have something to do with calling the variable in the prototype 'get' but I think I've seen examples like this where they name javascript classes and use a custom method that they call get. It seems to work for other calls.

Do you have any advice on why it doesn't work for this call?

Answer 1

The error is completely correct.

You defined MyResult.prototype.get , which has nothing to do with MyResult.get .

You probably want to create an instance.

Answer 2

It's a prototype function

So you have to test get function with an instance of an object like this:

it('should have a placeholder for get', function(){
    var resultObj = new MyResult(); // Create an instance of your object
    expect(function(){return resultObj.get(123);}).toThrowError(NotImplementedError);
});