Add fail spec for ruby-grape#1757

lib/grape/middleware/error.rb

@@ -127,13 +127,7 @@ def run_rescue_handler(handler, error)
           handler = public_method(handler)
         end
 
-        response = handler.arity.zero? ? instance_exec(&handler) : instance_exec(error, &handler)
-        valid_response?(response) ? response : run_rescue_handler(:default_rescue_handler, error)
-      end
-
-      def valid_response?(response)
-        # Rack::Response.new(...).finish generates an array with size 3
-        response.is_a?(Array) && response.size == 3
+        handler.arity.zero? ? instance_exec(&handler) : instance_exec(error, &handler)
       end
     end
   end

spec/grape/api_spec.rb

@@ -1724,30 +1724,16 @@ class CustomError < Grape::Exceptions::Base; end
       expect(last_response.body).to eq('Formatter Error')
     end
 
-    context 'validates response processed by exception handler' do
-      it 'calls default_rescue_handler when response is invalid' do
-        subject.rescue_from :all do
-          error!('Internal Server Error')
-          nil # invalid response caused by return nil
-        end
-        subject.get('/invalid_response') { raise 'rain!' }
-
-        expect_any_instance_of(Grape::Middleware::Error).to receive(:default_rescue_handler).and_call_original
-        get '/invalid_response'
-        expect(last_response.status).to eql 500
-        expect(last_response.body).to eq('rain!')
+    it 'can rescue exception no mater what returned by rescue_from' do
+      subject.rescue_from :all do
+        error!('Internal Server Error')
+        Grape::API.logger.error('Internal Server Error')
       end
+      subject.get('/') { raise 'rain!' }
 
-      it 'calls custom handler when response is valid' do
-        subject.rescue_from :all do
-          error!('Internal Server Error')
-        end
-        subject.get('/valid_response') { raise 'rain!' }
-
-        get '/valid_response'
-        expect(last_response.status).to eql 500
-        expect(last_response.body).to eq('Internal Server Error')
-      end
+      get '/'
+      expect(last_response.status).to eql 500
+      expect(last_response.body).to eq 'Internal Server Error'
     end
   end