Testing a REST API with Frisby.js

When our web app depends on pulling data through a REST API, we need to test that the endpoints well. Thats where things become more complicated and tedious to do manually. Two great libraries, Jasmine.js and Frisby.js, can help us out here.

What is Frisby and how does it work?

We are software developers and we strive to write good code.  We try to ensure the quality of every line and workflow which in turn means testing.  Manual testing works to a point but without automated testing of REST APIs and Ajax endpoint regression testing becomes cumbersome.  Are you really going to test all the possibilities/permutations with Postman?  I didn’t think so.

Testing a REST API is not so different to testing modules, but to create “end-to-end” test cases we needed make real endpoints calls. A manual testing job quickly becomes a tedious task, so we need to find a way to make things automated.

Frisby is a REST testing framework built on node.js and jasmine, and makes testing API endpoints a very flexible and easy task.

As any normal npm package running in node, Frisby needs node.js installed first, after that you can install Frisby as a common package:

npm install -g frisby

By convention, the file name containing the Test Suite, should include the trailing word “_spec.js”, node.js runs in javascript so logically js is the extension.

In order to continue our intrduction we will study the roleAPI_spec.js, a test suite part of the package Users of Erdiko Framework:

var frisby = require('../node_modules/frisby/lib/frisby');

This is the “kickoff” for our test suite, we instance the library in a Frisby variable, it will be our object to along  the suite.

describe('Role api test suite', function() {
  var baseURL = 'http://docker.local:8088/ajax/users/roles/';
  /**---This case test the api response and check the result----*/

  frisby.create('Get all roles')
        .get(baseURL + 'roles')
        .expectStatus(200)
        .expectHeader('Content-Type', 'application/json')
        .afterJSON(function (response) {          
            expect(response.body.method).toBe('roles');
            expect(response.body.success).toBe(true);          
            expect(response.errors).toBe(false);
            expect(response.body.roles).toBeDefined();
        })     
        .toss()
});

All  Frisby test starts with frisby.create(‘A gently worded description of test’) and next we must specify the verb to make the call to our endpoint. It is obvious but must match with the endpoint structure.

In our case we used .get(baseURL + ‘roles’)

Differences between using post or get.

There are differences between verbs post and get. When we create post test cases, we should pass objects as arguments, let’s see an example grabbed from userAPI_spec.js from Users package of Erdiko framework:

/*---------------------------------------------------------*/
/*-----------------Create User success --------------------*/
frisby.create('Creation will success.')
 .post(baseURL + 'register',
 {"name":"NameTest",
  "email":"test@email.com",
  "password":"secret"},
 { json: true },
 post_header)
 .expectStatus(200)
 .toss()

By default, Frisby sends POST and PUT requests as application/x-www-form-urlencoded parameters. If we want to send a raw request content, we must use { json: true } as the third argument to the .post().

Using Expectations.

/**--checking creation with expectations --*/
frisby.create('Checking user created exist.')
    .get(baseURL + 'retrieve?id=' + USER_ID)
    .expectStatus(200)
    .afterJSON(function (response) {
        expect(response.body.method).toBe('retrieve');
        expect(response.body.success).toBe(true);
        expect(response.body.user.id).toBe(response.body.user.id);
        expect(response.body.user.email).toBe(newUser.email);
        expect(response.body.user.name).toBe(newUser.name);
        expect(response.body.user.role.id).toBe(newUser.role);
    })
   .toss()

In comparison with our traditional phpunit, the framework to create unit test cases in php, we could say that phpunit Asserts are analog to Frisby Expectations. In particular, we are interested by that expectations to handle json code. Because that we are use the ‘expect’ clause that compare the API response with a parameter provided by us:

expect(response.body.method).toBe('retrieve')

Here we expect that ‘response.body.method’ be equals to the string ‘retrieve’. It’s important to mention that the comparison is by type and value at same time and both should match to result ‘true’.

After explain that we have a few expectations used:

  • expectJSON( [path], json )
  • expectJSONTypes( [path], json )

Managing Headers, afterJSON()

/**-----------delete user created ----------------*/
frisby.create('removing user created.')
    .get(baseURL + 'cancel?id=' + USER_ID)
    .expectStatus(200)
    .afterJSON(function (response) {
        expect(response.body.method).toBe('cancel');
        expect(response.body.success).toBe(true);
        expect(response.body.user.id).toBe(USER_ID);
    })
   .toss()

As we said previously, Frisby is an extension of Jasmine.node, and afterJSON is a very good evidence because afterJSON is the extension of after() with the convenience of parse the body obtained as response as JSON values automatically. The ‘after’ occurs immediately after the response is sent from the endpoint call and is used as a callback.

Using inspectors, inspectJSON()

Inspector helpers are useful for viewing details about the HTTP response when the test does not pass, or has trouble for some reason. They are also useful for debugging the API itself as a more user-friendly alternative to curl.

// Console output
{ url: 'http://theurl/get?foo=bar',
    headers:
    { 'Content-Length': '',
        'X-Forwarded-Port': '80',
        Connection: 'keep-alive',
        Host: 'httphost.org',
        Cookie: '',
        'Content-Type': 'application/json' },
    args: { foo: 'bar'},
    origin: '127.0.0.1' }

Basically inspectJSON() prints the raw HTTP response, other similar and general inspectors are:

  • inspectBody()
  • inspectHeaders()
  • InspectRequest()
  • InspectStatus()

Conclusion

Frisby makes it possible to write end-to-end tests with a lot of flexible tools and the process of test a complete REST API turns fun and easy. We miss the ability to ‘serialize’ test cases as in a regular test unit framework. Given the nature of javascript its possible to chain nested test cases and mimic, in some aspect, that behaviors.

We haven’t tried Newman yet, but hope to soon.  Let us know about your Frisby (and Newman) experiences.