add ability to specify custom exception handlers

change approach in exception handlers

- Allow only method name or status code as handler
- Don't require to return array with code and body

use handler as void function

Another change in exception handling apporach

- Remove `exception_code` in favour of `exception_handler` in Configuration
- Add Thorwable::Handlers, which defines handlers for all status codes
- Remove ability to specify handlers by status code in favour of explicit handlers

Rename class name to reflect recent changes

ruby 2.0.0 compatibility changes

Revert "Another change in exception handling apporach"

This reverts commit 3ee3620.

Revert "Rename class name to reflect recent changes"

This reverts commit e3c9d82.

Revert "ruby 2.0.0 compatibility changes"

This reverts commit 7729415.

small code cleanup

Don’t use protected handled_exceptions method

Rename `exception_code` to `exception_code` which returns either exception code, or handler name

lib/lotus/action/throwable.rb

@@ -74,8 +74,8 @@ def handle_exception(exception)
       # @see Lotus::Controller#handled_exceptions
       # @see Lotus::Action::Throwable#handle_exception
       # @see Lotus::Http::Status:ALL
-      def halt(code)
-        status(*Http::Status.for_code(code))
+      def halt(code = nil)
+        status(*Http::Status.for_code(code)) if code
         throw :halt
       end
 
@@ -124,7 +124,14 @@ def _dump_exception(exception)
       # @api private
       def _handle_exception(exception)
         raise unless configuration.handle_exceptions
-        halt configuration.exception_code(exception.class)
+        handler = configuration.exception_handler(exception.class)
+
+        if handler.is_a?(Symbol)
+          method(handler).call(exception)
+          halt
+        else
+          halt handler
+        end
       end
     end
   end

lib/lotus/controller/configuration.rb

@@ -192,7 +192,7 @@ def handle_exception(exception)
       # @api private
       #
       # @see Lotus::Controller::Configuration#handle_exception
-      def exception_code(exception)
+      def exception_handler(exception)
         @handled_exceptions.fetch(exception) { DEFAULT_ERROR_CODE }
       end
 

test/action_test.rb

@@ -30,13 +30,6 @@
       response[2].must_equal ['Hi from TestAction!']
     end
 
-    it 'returns an HTTP 500 status code when an exception is raised' do
-      response = ErrorCallAction.new.call({})
-
-      response[0].must_equal 500
-      response[2].must_equal ['Internal Server Error']
-    end
-
     it 'exposes validation errors' do
       action     = ParamsValidationAction.new
       code, _, _ = action.call({})
@@ -45,6 +38,29 @@
       action.errors.for(:email).must_include Lotus::Validations::Error.new(:email, :presence, true, nil)
     end
 
+    describe 'when exception handling code is enabled' do
+      it 'returns an HTTP 500 status code when an exception is raised' do
+        response = ErrorCallAction.new.call({})
+
+        response[0].must_equal 500
+        response[2].must_equal ['Internal Server Error']
+      end
+
+      it 'handles exception with specified method' do
+        response = ErrorCallWithMethodNameAsHandlerAction.new.call({})
+
+        response[0].must_equal 501
+        response[2].must_equal ['Please go away!']
+      end
+
+      it 'handles exception with specified status code' do
+        response = ErrorCallWithSpecifiedStatusCodeAction.new.call({})
+
+        response[0].must_equal 422
+        response[2].must_equal ['Unprocessable Entity']
+      end
+    end
+
     describe 'when exception handling code is disabled' do
       before do
         ErrorCallAction.configuration.handle_exceptions = false

test/configuration_test.rb

@@ -44,10 +44,10 @@ module CustomAction
     end
   end
 
-  describe 'exception_code' do
+  describe 'exception_handler' do
     describe 'when the given error is unknown' do
       it 'returns the default value' do
-        @configuration.exception_code(Exception).must_equal 500
+        @configuration.exception_handler(Exception).must_equal 500
       end
     end
 
@@ -56,8 +56,8 @@ module CustomAction
         @configuration.handle_exception NotImplementedError => 400
       end
 
-      it 'returns the default value' do
-        @configuration.exception_code(NotImplementedError).must_equal 400
+      it 'returns given value' do
+        @configuration.exception_handler(NotImplementedError).must_equal 400
       end
     end
   end

test/fixtures.rb

@@ -101,6 +101,31 @@ def call(params)
   end
 end
 
+class ErrorCallWithMethodNameAsHandlerAction
+  include Lotus::Action
+
+  handle_exception StandardError => :handler
+
+  def call(params)
+    raise StandardError
+  end
+
+  private
+  def handler(exception)
+    status 501, 'Please go away!'
+  end
+end
+
+class ErrorCallWithSpecifiedStatusCodeAction
+  include Lotus::Action
+
+  handle_exception StandardError => 422
+
+  def call(params)
+    raise StandardError
+  end
+end
+
 class ExposeAction
   include Lotus::Action