Memoize the result of Grape::Middleware::Base#response.

Signed-off-by: Hermann Mayer <[email protected]>

Author: Jack12816

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#2192](https://github.com/ruby-grape/grape/pull/2192): Memoize the result of Grape::Middleware::Base#response - [@Jack12816](https://github.com/Jack12816).
 * Your contribution here.
 
 ### 1.6.0 (2021/10/04)

lib/grape/middleware/base.rb

@@ -60,7 +60,7 @@ def after; end
       def response
         return @app_response if @app_response.is_a?(Rack::Response)
 
-        Rack::Response.new(@app_response[2], @app_response[0], @app_response[1])
+        @app_response = Rack::Response.new(@app_response[2], @app_response[0], @app_response[1])
       end
 
       def content_type_for(format)

spec/grape/middleware/base_spec.rb

@@ -77,42 +77,46 @@
   describe '#response' do
     subject { Grape::Middleware::Base.new(response) }
 
+    before { subject.call({}) }
+
     context Array do
       let(:response) { ->(_) { [204, { abc: 1 }, 'test'] } }
 
       it 'status' do
-        subject.call({})
         expect(subject.response.status).to eq(204)
       end
 
       it 'body' do
-        subject.call({})
         expect(subject.response.body).to eq(['test'])
       end
 
       it 'header' do
-        subject.call({})
         expect(subject.response.header).to have_key(:abc)
       end
+
+      it 'returns the memoized Rack::Response instance' do
+        expect(subject.response).to be(subject.response)
+      end
     end
 
     context Rack::Response do
       let(:response) { ->(_) { Rack::Response.new('test', 204, abc: 1) } }
 
       it 'status' do
-        subject.call({})
         expect(subject.response.status).to eq(204)
       end
 
       it 'body' do
-        subject.call({})
         expect(subject.response.body).to eq(['test'])
       end
 
       it 'header' do
-        subject.call({})
         expect(subject.response.header).to have_key(:abc)
       end
+
+      it 'returns the memoized Rack::Response instance' do
+        expect(subject.response).to be(subject.response)
+      end
     end
   end