CODEWITHSUNDEEP
javascriptunit-testing
ThinkBonobo
ThinkBonobo

Reputation: 16515

Wrong type of error when testing javascript function

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?

Upvotes: 1

Views: 100

Answers (2)

TaoPR
TaoPR

Reputation: 6052

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);
});

Upvotes: 1

SLaks
SLaks

Reputation: 887413

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.

Upvotes: 4

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