add rescue_from :exception to truly rescue all exceptions

Author: Jelkster

.rubocop_todo.yml

@@ -39,7 +39,7 @@ Metrics/BlockLength:
 # Offense count: 9
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 288
+  Max: 290
 
 # Offense count: 32
 Metrics/CyclomaticComplexity:
@@ -54,7 +54,7 @@ Metrics/LineLength:
 # Offense count: 57
 # Configuration parameters: CountComments.
 Metrics/MethodLength:
-  Max: 33
+  Max: 34
 
 # Offense count: 11
 # Configuration parameters: CountComments.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 #### Features
 
+* [#1754](https://github.com/ruby-grape/grape/pull/1754): Added `rescue_from :exception` to truly rescue from all exceptions - [@jelkster](https://github.com/jelkster).
 * Your contribution here.
 
 #### Fixes

README.md

@@ -2083,6 +2083,14 @@ end
 This mimics [default `rescue` behaviour](https://ruby-doc.org/core/StandardError.html) when an exception type is not provided.
 Any other exception should be rescued explicitly, see [below](#exceptions-that-should-be-rescued-explicitly).
 
+In the event you want to truly rescue all exceptions, this can be done.
+
+```ruby
+class Twitter::API < Grape::API
+  rescue_from :exception
+end
+```
+
 Grape can also rescue from all exceptions and still use the built-in exception handing.
 This will give the same behavior as `rescue_from :all` with the addition that Grape will use the exception handling defined by all Exception classes that inherit `Grape::Exceptions::Base`.
 
@@ -2289,7 +2297,7 @@ Here `'inner'` will be result of handling occured `ArgumentError`.
 
 Any exception that is not subclass of `StandardError` should be rescued explicitly.
 Usually it is not a case for an application logic as such errors point to problems in Ruby runtime.
-This is following [standard recomendations for exceptions handling](https://ruby-doc.org/core/Exception.html).
+This is following [standard recommendations for exceptions handling](https://ruby-doc.org/core/Exception.html).
 
 ### Rails 3.x
 

lib/grape/dsl/request_response.rb

@@ -116,6 +116,9 @@ def rescue_from(*args, &block)
           elsif args.include?(:grape_exceptions)
             namespace_inheritable(:rescue_all, true)
             namespace_inheritable(:rescue_grape_exceptions, true)
+          elsif args.include?(:exception)
+            namespace_inheritable(:rescue_exception, true)
+            namespace_inheritable(:exception_rescue_handler, handler)
           else
             handler_type =
               case options[:rescue_subclasses]

lib/grape/endpoint.rb

@@ -285,12 +285,14 @@ def build_stack(helpers)
                 default_status: namespace_inheritable(:default_error_status),
                 rescue_all: namespace_inheritable(:rescue_all),
                 rescue_grape_exceptions: namespace_inheritable(:rescue_grape_exceptions),
+                rescue_exception: namespace_inheritable(:rescue_exception),
                 default_error_formatter: namespace_inheritable(:default_error_formatter),
                 error_formatters: namespace_stackable_with_hash(:error_formatters),
                 rescue_options: namespace_stackable_with_hash(:rescue_options) || {},
                 rescue_handlers: namespace_reverse_stackable_with_hash(:rescue_handlers) || {},
                 base_only_rescue_handlers: namespace_stackable_with_hash(:base_only_rescue_handlers) || {},
-                all_rescue_handler: namespace_inheritable(:all_rescue_handler)
+                all_rescue_handler: namespace_inheritable(:all_rescue_handler),
+                exception_rescue_handler: namespace_inheritable(:exception_rescue_handler)
 
       stack.concat namespace_stackable(:middleware)
 

lib/grape/middleware/error.rb

@@ -13,6 +13,7 @@ def default_options
           error_formatters: {},
           rescue_all: false, # true to rescue all exceptions
           rescue_grape_exceptions: false,
+          rescue_exception: false,
           rescue_subclasses: true, # rescue subclasses of exceptions listed
           rescue_options: {
             backtrace: false, # true to display backtrace, true to let Grape handle Grape::Exceptions
@@ -36,7 +37,7 @@ def call!(env)
           error_response(catch(:error) do
             return @app.call(@env)
           end)
-        rescue StandardError => e
+        rescue Exception => e # rubocop:disable Lint/RescueException
           is_rescuable = rescuable?(e.class)
           if e.is_a?(Grape::Exceptions::Base) && (!is_rescuable || rescuable_by_grape?(e.class))
             handler = ->(arg) { error_response(arg) }
@@ -46,21 +47,14 @@ def call!(env)
           end
 
           handler.nil? ? handle_error(e) : exec_handler(e, &handler)
-        rescue Exception => e # rubocop:disable Lint/RescueException
-          handler = options[:rescue_handlers].find do |error_class, error_handler|
-            break error_handler if e.class <= error_class
-          end
-
-          raise unless handler
-
-          exec_handler(e, &handler)
         end
       end
 
       def find_handler(klass)
         handler = options[:rescue_handlers].find(-> { [] }) { |error, _| klass <= error }[1]
         handler ||= options[:base_only_rescue_handlers][klass]
         handler ||= options[:all_rescue_handler]
+        handler ||= options[:exception_rescue_handler]
 
         if handler.instance_of?(Symbol)
           raise NoMethodError, "undefined method `#{handler}'" unless respond_to?(handler)
@@ -72,7 +66,12 @@ def find_handler(klass)
 
       def rescuable?(klass)
         return false if klass == Grape::Exceptions::InvalidVersionHeader
-        rescue_all? || rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+
+        if klass <= StandardError
+          rescue_all? || rescue_exception? || rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+        else
+          rescue_exception? || rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+        end
       end
 
       def rescuable_by_grape?(klass)
@@ -129,6 +128,10 @@ def rescue_all?
         options[:rescue_all]
       end
 
+      def rescue_exception?
+        options[:rescue_exception]
+      end
+
       def rescue_class_or_its_ancestor?(klass)
         (options[:rescue_handlers] || []).any? { |error, _handler| klass <= error }
       end

spec/grape/dsl/request_response_spec.rb

@@ -157,6 +157,47 @@ def self.imbue(key, value)
           end
         end
 
+        describe ':exception' do
+          it 'sets rescue_exception to true' do
+            expect(subject).to receive(:namespace_inheritable).with(:rescue_exception, true)
+            expect(subject).to receive(:namespace_inheritable).with(:exception_rescue_handler, nil)
+            subject.rescue_from :exception
+          end
+
+          it 'sets given proc as rescue handler' do
+            rescue_handler_proc = proc {}
+            expect(subject).to receive(:namespace_inheritable).with(:rescue_exception, true)
+            expect(subject).to receive(:namespace_inheritable).with(:exception_rescue_handler, rescue_handler_proc)
+            subject.rescue_from :exception, rescue_handler_proc
+          end
+
+          it 'sets given block as rescue handler' do
+            rescue_handler_proc = proc {}
+            expect(subject).to receive(:namespace_inheritable).with(:rescue_exception, true)
+            expect(subject).to receive(:namespace_inheritable).with(:exception_rescue_handler, rescue_handler_proc)
+            subject.rescue_from :exception, &rescue_handler_proc
+          end
+
+          it 'sets a rescue handler declared through :with option' do
+            with_block = -> { 'hello' }
+            expect(subject).to receive(:namespace_inheritable).with(:rescue_exception, true)
+            expect(subject).to receive(:namespace_inheritable).with(:exception_rescue_handler, an_instance_of(Proc))
+            subject.rescue_from :exception, with: with_block
+          end
+
+          it 'abort if :with option value is not Symbol, String or Proc' do
+            expect { subject.rescue_from :exception, with: 1234 }.to raise_error(ArgumentError, "with: #{integer_class_name}, expected Symbol, String or Proc")
+          end
+
+          it 'abort if both :with option and block are passed' do
+            expect do
+              subject.rescue_from :exception, with: -> { 'hello' } do
+                error!('bye')
+              end
+            end.to raise_error(ArgumentError, 'both :with option and block cannot be passed')
+          end
+        end
+
         describe 'list of exceptions is passed' do
           it 'sets hash of exceptions as rescue handlers' do
             expect(subject).to receive(:namespace_reverse_stackable).with(:rescue_handlers, StandardError => nil)

spec/grape/middleware/exception_spec.rb

@@ -110,18 +110,35 @@ def app
   end
 
   context 'Non-StandardError exception with a provided rescue handler' do
-    subject do
-      Rack::Builder.app do
-        use Spec::Support::EndpointFaker
-        use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => -> { [200, {}, 'rescued'] } }
-        run ExceptionSpec::OtherExceptionApp
+    context 'default error response' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => nil }
+          run ExceptionSpec::OtherExceptionApp
+        end
+      end
+      it 'rescues the exception using the default handler' do
+        get '/'
+        expect(last_response.body).to eq('snow!')
       end
     end
-    it 'rescues the exception using the provided handler' do
-      get '/'
-      expect(last_response.body).to eq('rescued')
+
+    context 'custom error response' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => -> { [200, {}, 'rescued'] } }
+          run ExceptionSpec::OtherExceptionApp
+        end
+      end
+      it 'rescues the exception using the provided handler' do
+        get '/'
+        expect(last_response.body).to eq('rescued')
+      end
     end
   end
+
   context do
     subject do
       Rack::Builder.app do
@@ -324,4 +341,42 @@ def app
       expect(last_response.body).to include('error', 'rain!', 'backtrace', 'original exception', 'RuntimeError')
     end
   end
+
+  context 'with rescue_exception' do
+    context 'StandardError raised' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_exception: true
+          run ExceptionSpec::ExceptionApp
+        end
+      end
+      it 'sets the message appropriately' do
+        get '/'
+        expect(last_response.body).to eq('rain!')
+      end
+      it 'defaults to a 500 status' do
+        get '/'
+        expect(last_response.status).to eq(500)
+      end
+    end
+
+    context 'Non-StandardError raised' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_exception: true
+          run ExceptionSpec::OtherExceptionApp
+        end
+      end
+      it 'sets the message appropriately' do
+        get '/'
+        expect(last_response.body).to eq('snow!')
+      end
+      it 'defaults to a 500 status' do
+        get '/'
+        expect(last_response.status).to eq(500)
+      end
+    end
+  end
 end