How to check for a JSON response using RSpec? - ruby-on-rails

Question

I have the following code in my controller:
format.json { render :json => {
:flashcard => #flashcard,
:lesson => #lesson,
:success => true
}
In my RSpec controller test I want to verify that a certain scenario does receive a success json response so I had the following line:
controller.should_receive(:render).with(hash_including(:success => true))
Although when I run my tests I get the following error:
Failure/Error: controller.should_receive(:render).with(hash_including(:success => false))
(#<AnnoController:0x00000002de0560>).render(hash_including(:success=>false))
expected: 1 time
received: 0 times
Am I checking the response incorrectly?

Answer 1

You could parse the response body like this:
parsed_body = JSON.parse(response.body)
Then you can make your assertions against that parsed content.
parsed_body["foo"].should == "bar"

Answer 2

You can examine the response object and verify that it contains the expected value:
#expected = {
:flashcard => #flashcard,
:lesson => #lesson,
:success => true
}.to_json
get :action # replace with action name / params as necessary
response.body.should == #expected
EDIT
Changing this to a post makes it a bit trickier. Here's a way to handle it:
it "responds with JSON" do
my_model = stub_model(MyModel,:save=>true)
MyModel.stub(:new).with({'these' => 'params'}) { my_model }
post :create, :my_model => {'these' => 'params'}, :format => :json
response.body.should == my_model.to_json
end
Note that mock_model will not respond to to_json, so either stub_model or a real model instance is needed.

Answer 3

Building off of Kevin Trowbridge's answer
response.header['Content-Type'].should include 'application/json'

Answer 4

There's also the json_spec gem, which is worth a look
https://github.com/collectiveidea/json_spec

Answer 5

Simple and easy to way to do this.
# set some variable on success like :success => true in your controller
controller.rb
render :json => {:success => true, :data => data} # on success
spec_controller.rb
parse_json = JSON(response.body)
parse_json["success"].should == true

Answer 6

You can also define a helper function inside spec/support/
module ApiHelpers
def json_body
JSON.parse(response.body)
end
end
RSpec.configure do |config|
config.include ApiHelpers, type: :request
end
and use json_body whenever you need to access the JSON response.
For example, inside your request spec you can use it directly
context 'when the request contains an authentication header' do
it 'should return the user info' do
user = create(:user)
get URL, headers: authenticated_header(user)
expect(response).to have_http_status(:ok)
expect(response.content_type).to eq('application/vnd.api+json')
expect(json_body["data"]["attributes"]["email"]).to eq(user.email)
expect(json_body["data"]["attributes"]["name"]).to eq(user.name)
end
end

Answer 7

Another approach to test just for a JSON response (not that the content within contains an expected value), is to parse the response using ActiveSupport:
ActiveSupport::JSON.decode(response.body).should_not be_nil
If the response is not parsable JSON an exception will be thrown and the test will fail.

Answer 8

You could look into the 'Content-Type' header to see that it is correct?
response.header['Content-Type'].should include 'text/javascript'

Answer 9

When using Rails 5 (currently still in beta), there's a new method, parsed_body on the test response, which will return the response parsed as what the last request was encoded at.
The commit on GitHub: https://github.com/rails/rails/commit/eee3534b

Answer 10

A lot of the above answers are a bit out of date, so this is a quick summary for a more recent version of RSpec (3.8+). This solution raises no warnings from rubocop-rspec and is inline with rspec best practices:
A successful JSON response is identified by two things:
The content type of the response is application/json
The body of the response can be parsed without errors
Assuming that the response object is the anonymous subject of the test, both of the above conditions can be validate using Rspec's built in matchers:
context 'when response is received' do
subject { response }
# check for a successful JSON response
it { is_expected.to have_attributes(content_type: include('application/json')) }
it { is_expected.to have_attributes(body: satisfy { |v| JSON.parse(v) }) }
# validates OP's condition
it { is_expected.to satisfy { |v| JSON.parse(v.body).key?('success') }
it { is_expected.to satisfy { |v| JSON.parse(v.body)['success'] == true }
end
If you're prepared to name your subject then the above tests can be simplified further:
context 'when response is received' do
subject(:response) { response }
it 'responds with a valid content type' do
expect(response.content_type).to include('application/json')
end
it 'responds with a valid json object' do
expect { JSON.parse(response.body) }.not_to raise_error
end
it 'validates OPs condition' do
expect(JSON.parse(response.body, symoblize_names: true))
.to include(success: true)
end
end

Answer 11

JSON comparison solution
Yields a clean but potentially large Diff:
actual = JSON.parse(response.body, symbolize_names: true)
expected = { foo: "bar" }
expect(actual).to eq expected
Example of console output from real data:
expected: {:story=>{:id=>1, :name=>"The Shire"}}
got: {:story=>{:id=>1, :name=>"The Shire", :description=>nil, :body=>nil, :number=>1}}
(compared using ==)
Diff:
## -1,2 +1,2 ##
-:story => {:id=>1, :name=>"The Shire"},
+:story => {:id=>1, :name=>"The Shire", :description=>nil, ...}
(Thanks to comment by #floatingrock)
String comparison solution
If you want an iron-clad solution, you should avoid using parsers which could introduce false positive equality; compare the response body against a string. e.g:
actual = response.body
expected = ({ foo: "bar" }).to_json
expect(actual).to eq expected
But this second solution is less visually friendly as it uses serialized JSON which would include lots of escaped quotation marks.
Custom matcher solution
I tend to write myself a custom matcher that does a much better job of pinpointing at exactly which recursive slot the JSON paths differ. Add the following to your rspec macros:
def expect_response(actual, expected_status, expected_body = nil)
expect(response).to have_http_status(expected_status)
if expected_body
body = JSON.parse(actual.body, symbolize_names: true)
expect_json_eq(body, expected_body)
end
end
def expect_json_eq(actual, expected, path = "")
expect(actual.class).to eq(expected.class), "Type mismatch at path: #{path}"
if expected.class == Hash
expect(actual.keys).to match_array(expected.keys), "Keys mismatch at path: #{path}"
expected.keys.each do |key|
expect_json_eq(actual[key], expected[key], "#{path}/:#{key}")
end
elsif expected.class == Array
expected.each_with_index do |e, index|
expect_json_eq(actual[index], expected[index], "#{path}[#{index}]")
end
else
expect(actual).to eq(expected), "Type #{expected.class} expected #{expected.inspect} but got #{actual.inspect} at path: #{path}"
end
end
Example of usage 1:
expect_response(response, :no_content)
Example of usage 2:
expect_response(response, :ok, {
story: {
id: 1,
name: "Shire Burning",
revisions: [ ... ],
}
})
Example output:
Type String expected "Shire Burning" but got "Shire Burnin" at path: /:story/:name
Another example output to demonstrate a mismatch deep in a nested array:
Type Integer expected 2 but got 1 at path: /:story/:revisions[0]/:version
As you can see, the output tells you EXACTLY where to fix your expected JSON.

Answer 12

If you want to take advantage of the hash diff Rspec provides, it is better to parse the body and compare against a hash. Simplest way I've found:
it 'asserts json body' do
expected_body = {
my: 'json',
hash: 'ok'
}.stringify_keys
expect(JSON.parse(response.body)).to eql(expected_body)
end

Answer 13

I found a customer matcher here: https://raw.github.com/gist/917903/92d7101f643e07896659f84609c117c4c279dfad/have_content_type.rb
Put it in spec/support/matchers/have_content_type.rb and make sure to load stuff from support with something like this in you spec/spec_helper.rb
Dir[Rails.root.join('spec/support/**/*.rb')].each {|f| require f}
Here is the code itself, just in case it disappeared from the given link.
RSpec::Matchers.define :have_content_type do |content_type|
CONTENT_HEADER_MATCHER = /^(.*?)(?:; charset=(.*))?$/
chain :with_charset do |charset|
#charset = charset
end
match do |response|
_, content, charset = *content_type_header.match(CONTENT_HEADER_MATCHER).to_a
if #charset
#charset == charset && content == content_type
else
content == content_type
end
end
failure_message_for_should do |response|
if #charset
"Content type #{content_type_header.inspect} should match #{content_type.inspect} with charset #{#charset}"
else
"Content type #{content_type_header.inspect} should match #{content_type.inspect}"
end
end
failure_message_for_should_not do |model|
if #charset
"Content type #{content_type_header.inspect} should not match #{content_type.inspect} with charset #{#charset}"
else
"Content type #{content_type_header.inspect} should not match #{content_type.inspect}"
end
end
def content_type_header
response.headers['Content-Type']
end
end

Answer 14

For Your JSON response you should parse that response for expected results
For Instance: parsed_response = JSON.parse(response.body)
You can check other variables which is included in response like
expect(parsed_response["success"]).to eq(true)
expect(parsed_response["flashcard"]).to eq("flashcard expected value")
expect(parsed_response["lesson"]).to eq("lesson expected value")
expect(subject["status_code"]).to eq(201)
I prefer also check keys of JSON response, For Example:
expect(body_as_json.keys).to match_array(["success", "lesson","status_code", "flashcard"])
Here, We can use should matchers For expected results in Rspec