How to test a JSON REST API

Question

I'm brand new to ruby (first day working with ruby) so please forgive any novice questions and lack of understanding.

I'm trying to validate the responses to http callouts.

For example, let's say the endpoint is the following:

https://applicationname-api-sbox02.herokuapp.com

And, I'm trying to authenticate a user by sending a get request like this:

get_response = RestClient.get( "https://applicationname-api-sbox02.herokuapp.com/api/v1/users", 
                    {
                        "Content-Type" => "application/json",
                        "Authorization" => "token 4d012314b7e46008f215cdb7d120cdd7",
                        "Manufacturer-Token" => "8d0693ccfe65104600e2555d5af34213"
                    }
                )

Now, I want to validate the response and do the following: - parse the response to ensure that it is valid JSON - do some validation and verify the JSON has the correct data (verify that id == 4 for example) - if an error is encountered, raise an exception using the 'raise' method.

In my first feeble attempt I tried the following:

puts get_response.body
if get_response.code == 200
puts "********* Get current user successful"
else
puts "Get current user failed!!"
end

Now, this returned that getting the current user was successful, but how do I actually parse the json, verify the correct id, and raise an exception if an error occurred?

Duplicate of http://stackoverflow.com/questions/5410682/parsing-a-json-string-in-ruby — Aaron Kurtzhals, Dec 19 '12 at 15:17
@AaronKurtzhals: it's about setting up a test for client code, not strictly about parsing a JSON string. — Eric Walker, Dec 19 '12 at 16:28

ireddick · Accepted Answer · 2012-12-19T19:29:21.403

17

Instead of raising an exception, write a test.

A straightforward approach, using the json parser and unit test framework from the std lib:

require 'minitest/autorun'
require 'rest_client'
require 'json'

class APITest < MiniTest::Unit::TestCase
  def setup
    response = RestClient.get("https://applicationname-api-sbox02.herokuapp.com/api/v1/users", 
      {
         "Content-Type" => "application/json",
         "Authorization" => "token 4d012314b7e46008f215cdb7d120cdd7",
         "Manufacturer-Token" => "8d0693ccfe65104600e2555d5af34213"
      }
    ) 
    @data = JSON.parse response.body
  end

  def test_id_correct
    assert_equal 4, @data['id']
  end
end

Execute with ruby $filename

JSON.parse parses a JSON string into a ruby hash

Getting started with minitest

If you are using ruby 1.8, you'll need to install the json gem and either install the minitest gem, or switch to the older testunit API. If you choose the latter, then you'll need to change require 'minitest/autorun' -> require 'test/unit' and MiniTest::Unit::TestCase -> Test::Unit::TestCase

edited Dec 19 '12 at 19:29

answered Dec 19 '12 at 15:32

ireddick

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Hi @ireddick, thanks for the help. I tried your example, but got the error: uninitialized constant Minitest – Dman100 Dec 19 '12 at 15:42
I'm running 1.9.3p327 (2012-11-10) [i386-mingw321] – Dman100 Dec 19 '12 at 16:05
@Dman100 - "uninitialized constant Minitest" means you've mistyped MiniTest – ireddick Dec 19 '12 at 16:11
the test did run...thank you. Got an unexpected result though. It shows the expected result is "id" instead of the id value, which is 4. – Dman100 Dec 19 '12 at 16:29
Thanks @ireddick! Is there an eqivalent of assert not equals? – Dman100 Dec 19 '12 at 17:06
@Dman100 refute_equal - http://ruby-doc.org/stdlib-1.9.3/libdoc/minitest/unit/rdoc/MiniTest/Assertions.html#method-i-refute_equal – ireddick Dec 19 '12 at 17:12

score 4 · Answer 2 · answered Sep 18 '14 at 18:24

4

I'm a little late to the party, but I recently co-created an rspec driven framework called Airborne for just this purpose. Check it out: https://github.com/brooklynDev/airborne

answered Sep 18 '14 at 18:24

BFree

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Gabriel Pavel · Answer 3 · 2015-03-21T07:51:44.133

here is an example from our specs so you can see how we test json api:

it 'returns charge' do
  get "/charges/#{charge.id}", '', headers

  expect(response.status).to eq(200)
  expect(response).to match_response_schema(:charge)
  expect(response).to match_json(<<-JSON)
  {
    "id":"{id}",
    "email": "{email}",
    "ip": "127.0.0.1",
    "amount": 10500,
    "state": "captured",
    "captured_amount": 10500,
  }
  JSON
end

Lets look at it closely

match_response_schema(:charge)

This matcher checks that json we get in response is in general valid. We use json-schema (json schema validator) for it. Guys from Thoughtbot have a detailed guide how to use json schema validator and create own matcher in this blog post.

Understanding JSON Schema is where I got a lot of useful information on how to create schemas for JSON documents.

match_json

This is our own matcher and we have released match_json gem recently. Using it you can test structure and values of your json. Here are two great features of this matcher:

if you don't know exact values, you can use patterns like {id}, {uuid} {date_time}, etc. we have predefined patterns but you can add your own too.
you get clear failure message what is wrong with your json e.g. "5" was not found in " > array":[1,2,3]

score 0 · Answer 4 · answered Dec 19 '12 at 15:31

Parsing json can be done with the json gem: http://flori.github.com/json/

Parsed json is accessed through key/value just like in javascript. You can easily verify the values and conditionally raise errors.

Raising errors is done like so:

raise "the ID was #{id} instead of 4"

And writing unit tests can be done with Test::Unit - http://www.ruby-doc.org/stdlib-1.9.3/libdoc/test/unit/rdoc/Test/Unit.html

How to test a JSON REST API

4 Answers4