Introduce bang methods which raise exceptions when API returns errors

e.g.: mws_api.subscriptions.register_destination!(...)
Deprecate old methods (with no bangs)

README.markdown

@@ -32,13 +32,14 @@ Using in a simple ruby file:
 To access the apis you can use:
 
 ```ruby
-     mws_api._api_name_._action_to_calll(params={})
+     mws_api._api_name_._action_to_call!(params={})
 ```
+The method above will return an error if any `ErrorResponse` is returned from MWS
 
 Let's say we want to retrieve a list of orders using MWS orders api:
 
 ```ruby
-    mws_api.orders.list_orders(
+    mws_api.orders.list_orders!(
       "MarketplaceId.Id.1" => "marketplace id",
       created_after: Time.new(2013, 1, 1)
     )

lib/mws.rb

@@ -9,6 +9,7 @@
 
 require_relative 'mws/query'
 require_relative 'mws/connection'
+require_relative 'mws/api'
 require_relative 'mws/api/base'
 require_relative 'mws/api/orders'
 require_relative 'mws/api/reports'

lib/mws/api.rb

@@ -0,0 +1,8 @@
+module MWS
+  # API module
+  module API
+    ResponseError = Class.new(StandardError)
+
+    RESPONSE_ERROR_KEY = 'ErrorResponse'.freeze
+  end
+end

lib/mws/api/base.rb

@@ -7,6 +7,7 @@ class Base
       # TODO: Temporary solution, move to configuration
       DEFAULT_TIMEOUT = 2000
       USER_AGENT = 'User-Agent'.freeze
+      STRICT_MEHTHOD_ENDING = '!'.freeze
 
       def initialize(connection)
         @verb ||= :get
@@ -43,19 +44,40 @@ def build_query_from_params(action, params)
 
       def method_missing(name, *args)
         if self.class::ACTIONS.include?(name)
+          warn "[DEPRECATION] `#{name}` will be removed in next major version. " \
+               "Please use `#{name}!` instead."
+
           call(name, *args)
+        elsif self.class::ACTIONS.include?(method_without_bang(name))
+          response = call(method_without_bang(name), *args)
+
+          return response unless response.key?(MWS::API::RESPONSE_ERROR_KEY)
+
+          raise MWS::API::ResponseError, response.to_json
         else
           super
         end
       end
 
+      def respond_to_missing?(name, include_private = false)
+        self.class::ACTIONS.include?(name) ||
+          self.class::ACTIONS.include?(method_without_bang(name)) ||
+          super
+      end
+
       def http_request_options
         @http_request_options ||= begin
           options = { timeout: DEFAULT_TIMEOUT }
           options.merge!(headers: { USER_AGENT => MWS.user_agent }) if MWS.user_agent.present?
           options
         end
       end
+
+      private
+
+      def method_without_bang(name)
+        name.to_s.chomp(STRICT_MEHTHOD_ENDING).to_sym
+      end
     end
   end
 end

spec/mws-rb/api/base_spec.rb

@@ -40,14 +40,89 @@ def initialize(connection)
   end
 
   describe 'method_missing to call actions' do
-    before(:each) { allow(HTTParty).to receive(:get).and_return({}) }
+    before(:each) { allow(HTTParty).to receive(:get).and_return(result) }
 
-    it 'should raise exception if Actions do not contain the action name' do
-      expect { test_api.action_not_found }.to raise_error(NoMethodError)
+    context 'regular method call' do
+      let(:result) { {} }
+      let(:expected_deprication_warning) do
+        '[DEPRECATION] `test_action` will be removed in next major version. ' \
+        "Please use `test_action!` instead.\n"
+      end
+
+      it 'should raise exception if Actions do not contain the action name', :stub_stdout do
+        expect { test_api.action_not_found }.to raise_error(NoMethodError)
+      end
+
+      it 'makes api call and return result if Actions contain the action name', :stub_stdout do
+        expect(test_api.test_action).to eq result
+      end
+
+      it 'prints a deprication warning' do
+        expect { test_api.test_action }
+          .to output(expected_deprication_warning)
+          .to_stderr
+      end
+    end
+
+    context 'bang method' do
+      context 'API response does not contain errors' do
+        let(:result) { {} }
+
+        it 'raises exception if Actions do not contain the action name' do
+          expect { test_api.action_not_found! }.to raise_error(NoMethodError)
+        end
+
+        it 'makes api call and return result if Actions contain the action name' do
+          expect(test_api.test_action!).to eq result
+        end
+      end
+
+      context 'API response contains errors' do
+        let(:result) { { 'ErrorResponse' => {} } }
+
+        it 'makes api call and returns error' do
+          expect { test_api.test_action! }
+            .to raise_error MWS::API::ResponseError, '{"ErrorResponse":{}}'
+        end
+      end
+    end
+  end
+
+  describe '#respond_to_missing?' do
+    subject { test_api.respond_to?(method_name) }
+
+    context 'Actions contain method' do
+      let(:method_name) { 'test_action' }
+
+      it { is_expected.to be true }
+    end
+
+    context 'Actions do not contain method' do
+      let(:method_name) { 'missed_test_action' }
+
+      it { is_expected.to be false }
+    end
+
+    context 'Actions contain bang method' do
+      let(:method_name) { 'test_action!' }
+
+      it { is_expected.to be true }
+    end
+
+    context 'Actions do not contain bang method' do
+      let(:method_name) { 'missed_test_action!' }
+
+      it { is_expected.to be false }
+    end
+
+    context 'regular Ruby method' do
+      let(:method_name) { 'nil?' }
+
+      it { is_expected.to be true }
     end
   end
 
-  context 'user agent' do
+  context 'user agent', :stub_stdout do
     subject { test_api.test_action(params) }
 
     before do |example|

spec/spec_helper.rb

@@ -14,4 +14,10 @@
   config.filter_sensitive_data('DUMMY_AWS_SELLER_ID')  { ENV['AWS_SELLER_ID']  }
 end
 
+RSpec.configure do |config|
+  config.before(:each, :stub_stdout) do
+    allow_any_instance_of(Kernel).to receive(:warn)
+  end
+end
+
 RSpec.configure(&:raise_errors_for_deprecations!)