Use default_rescue_handler when reponse is invalid

Author: darren987469

CHANGELOG.md

@@ -7,6 +7,7 @@
 #### Fixes
 
 * Your contribution here.
+* [#1776](https://github.com/ruby-grape/grape/pull/1776): Validates response processed by exception handler - [@darren987469](https://github.com/darren987469).
 
 ### 1.1.0 (8/4/2018)
 
@@ -21,7 +22,6 @@
 * [#1758](https://github.com/ruby-grape/grape/pull/1758): Fix expanding load_path in gemspec - [@2maz](https://github.com/2maz).
 * [#1765](https://github.com/ruby-grape/grape/pull/1765): Use 415 when request body is of an unsupported media type - [@jdmurphy](https://github.com/jdmurphy).
 * [#1771](https://github.com/ruby-grape/grape/pull/1771): Fix param aliases with 'given' blocks - [@jereynolds](https://github.com/jereynolds).
-* [#1776](https://github.com/ruby-grape/grape/pull/1776): Validates response processed by exception handler - [@darren987469](https://github.com/darren987469).
 
 ### 1.0.3 (4/23/2018)
 

lib/grape/middleware/error.rb

@@ -128,7 +128,7 @@ def run_rescue_handler(handler, error)
         end
 
         response = handler.arity.zero? ? instance_exec(&handler) : instance_exec(error, &handler)
-        valid_response?(response) ? response : error!('Internal Server Error(Invalid Response)')
+        valid_response?(response) ? response : run_rescue_handler(:default_rescue_handler, error)
       end
 
       def valid_response?(response)

spec/grape/api_spec.rb

@@ -1724,24 +1724,30 @@ class CustomError < Grape::Exceptions::Base; end
       expect(last_response.body).to eq('Formatter Error')
     end
 
-    it 'validates response processed by exception handler' do
-      subject.rescue_from ArgumentError do
-        error!('rain!')
-        nil # invalid response caused by return nil
-      end
-      subject.rescue_from :all do
-        error!('rain!')
+    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!')
       end
-      subject.get('/invalid_response') { raise ArgumentError }
-      subject.get('/valid_response') { raise 'rain!' }
 
-      get '/invalid_response'
-      expect(last_response.status).to eql 500
-      expect(last_response.body).to eq('Internal Server Error(Invalid Response)')
+      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('rain!')
+        get '/valid_response'
+        expect(last_response.status).to eql 500
+        expect(last_response.body).to eq('Internal Server Error')
+      end
     end
   end