Rubocop fixes

.rubocop.yml

@@ -28,3 +28,5 @@ Style/HashTransformKeys:
   Enabled: false
 Style/HashTransformValues:
   Enabled: false
+AllCops:
+  NewCops: enable

lib/omniauth/strategies/google_oauth2.rb

@@ -202,15 +202,16 @@ def image_size_opts_passed?
 
       def image_params
         image_params = []
-        if options[:image_size].is_a?(Integer)
+        case options[:image_size]
+        when Integer
           image_params << "s#{options[:image_size]}"
-        elsif options[:image_size].is_a?(Hash)
+        when Hash
           image_params << "w#{options[:image_size][:width]}" if options[:image_size][:width]
           image_params << "h#{options[:image_size][:height]}" if options[:image_size][:height]
         end
         image_params << 'c' if options[:image_aspect_ratio] == 'square'
 
-        '/' + image_params.join('-')
+        "/#{image_params.join('-')}"
       end
 
       def strip_unnecessary_query_parameters(query_parameters)

spec/omniauth/strategies/google_oauth2_spec.rb

@@ -324,20 +324,20 @@
     it 'has the correct default callback path' do
       allow(subject).to receive(:full_host) { base_url }
       allow(subject).to receive(:script_name) { '' }
-      expect(subject.send(:callback_url)).to eq(base_url + '/auth/google_oauth2/callback')
+      expect(subject.send(:callback_url)).to eq("#{base_url}/auth/google_oauth2/callback")
     end
 
     it 'should set the callback path with script_name if present' do
       allow(subject).to receive(:full_host) { base_url }
       allow(subject).to receive(:script_name) { '/v1' }
-      expect(subject.send(:callback_url)).to eq(base_url + '/v1/auth/google_oauth2/callback')
+      expect(subject.send(:callback_url)).to eq("#{base_url}/v1/auth/google_oauth2/callback")
     end
 
     it 'should set the callback_path parameter if present' do
       @options = { callback_path: '/auth/foo/callback' }
       allow(subject).to receive(:full_host) { base_url }
       allow(subject).to receive(:script_name) { '' }
-      expect(subject.send(:callback_url)).to eq(base_url + '/auth/foo/callback')
+      expect(subject.send(:callback_url)).to eq("#{base_url}/auth/foo/callback")
     end
   end