output success status on failure like discourse does

app/controllers/discourse_donations/charges_controller.rb

@@ -22,7 +22,7 @@ module DiscourseDonations
       end
 
       if output['messages'].present?
-        render(:json => output) and return
+        render(:json => output.merge(success: false)) and return
       end
 
       payment = DiscourseDonations::Stripe.new(secret_key, stripe_options)

spec/controllers/discourse_donations/charges_controller_spec.rb

@@ -1,6 +1,14 @@
 require 'rails_helper'
 require_relative '../../support/dd_helper'
 
+shared_examples 'failure response' do |message_key|
+  let(:body) { JSON.parse(response.body) }
+
+  it 'has status 200' do expect(response).to have_http_status(200) end
+  it 'has an error message' do expect(body['messages']).to include(I18n.t(message_key)) end
+  it 'is not successful' do expect(body['success']).to eq false end
+end
+
 module DiscourseDonations
   RSpec.describe ChargesController, type: :controller do
     routes { DiscourseDonations::Engine.routes }
@@ -12,10 +20,6 @@ module DiscourseDonations
       SiteSetting.stubs(:discourse_donations_currency).returns('AUD')
     end
 
-    def include_message(key)
-      include(I18n.t(key))
-    end
-
     it 'responds ok for anonymous users' do
       post :create, { email: 'foobar@example.com' }
       expect(body['messages']).to include('Payment complete.')
@@ -32,26 +36,32 @@ module DiscourseDonations
     describe 'new user' do
       let(:params) { { create_account: 'true', email: 'email@example.com', password: 'secret', username: 'mr-pink' } }
 
-      it 'requires an email' do
+      describe 'requires an email' do
-        post :create, params.merge(email: '')
+        before { post :create, params.merge(email: '') }
-        expect(body['messages']).to include_message('login.missing_user_field')
+        include_examples 'failure response', 'login.missing_user_field'
       end
 
-      it 'requires a username' do
+      describe 'requires a username' do
-        post :create, params.merge(username: '')
+        before { post :create, params.merge(username: '') }
-        expect(body['messages']).to include_message('login.missing_user_field')
+        include_examples 'failure response', 'login.missing_user_field'
       end
 
-      it 'disallows usernames that are reserved' do
+      describe 'reserved usernames' do
+        before do
           User.expects(:reserved_username?).returns(true)
           post :create, params
-        expect(body['messages']).to include_message('login.reserved_username')
         end
 
-      it 'requires a minimum password length' do
+        include_examples 'failure response', 'login.reserved_username'
+      end
+
+      describe 'minimum password length' do
+        before do
           User.expects(:max_password_length).returns(params[:password].length - 1)
           post :create, params
-        expect(body['messages']).to include_message('login.password_too_long')
+        end
+
+        include_examples 'failure response', 'login.password_too_long'
       end
     end