How to make a unit test for ajax calls

Question

I am a newbie in creating unit tests for JavaScripts. In my unit test I keep on getting "AssertError: expected "ok" but was [undefined] " as a result. Can any teach me how to do a unit test for ajax calls? Thanks. By the way, I'm using JsTestDriver for testing my unit tests.

Here's my source file:

function getReport(m, y)
{
$.ajax({
    url: "url/to",
    data: {
        m:m,
        y:y
    },
    dataType: 'json',
    success:function (res) {
            return res;

    }       
});

}

Here's my test file:

TestCase("Report", {

  "test get report": function () {
 assertEquals("ok", getReport(1, 2015));
}   
});

The `getReport` function does not return a value. What's returning the value is the success callback which is called asynchronously. The framework you are using should have some way of delaying the assertion until the callback is executed. But I can't be more helpful as I don't have experience on js unit testing :( — Diego, Jan 24 '15 at 02:59

score 4 · Accepted Answer · edited May 23 '17 at 12:09

Before we go further with your question let me ask mine: why do you need to test Ajax requests? Generally, with unit tests you don't test vendor code and functionality such as 3rd party functions, APIs, network issues, database etc. Focus on unit testing the code your team and you created. Let vendor test their code. In this particular example, jQuery Ajax should be tested by jQuery provider, not you.

There is another reason why you shouldn't test Ajax: the test will transfer from unit to integration test because you test that backend returns the correct value from server. That being said, you test how client+server code work together.

The right way to go is to isolate your unit test from external calls by using mocks, spy or stubs. If you are unsure what they are - search in the Internet. All the popular unit testing frameworks and libraries support and provide the easy way to use them.

You might want to test it anyway, for this purpose visit a related post: Unit testing AJAX requests with QUnit

Good luck with unit tests!

Why test Ajax requests? 1. Because endpoints can and do change/break. Having a SMALL test example makes it easier to debug what went wrong. 2. We've also recently ripped jQuery out of our code base because it bloated for our uses -- we have migrated everything over to native Javascript sans $.ajax(). This means we needed to verify what jQuery is doing internally and make sure our native replacement is implementing/emulating the API correctly. — Michaelangel007, Sep 14 '17 at 21:36

How to make a unit test for ajax calls

1 Answers1