Rescue exception autocorrect

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### New features
 
+* [#966](https://github.com/bbatsov/rubocop/issues/966): `RescueException` cop does auto-correction. ([@tamird][])
 * [#967](https://github.com/bbatsov/rubocop/issues/967): `TrivialAccessors` cop does auto-correction. ([@tamird][])
 * [#963](https://github.com/bbatsov/rubocop/issues/963): Add `AllowDSLWriters` options to `TrivialAccessors`. ([@tamird][])
 * [#969](https://github.com/bbatsov/rubocop/issues/969): Let the `Debugger` cop check for forgotten calls to byebug. ([@bquorning][])

lib/rubocop/cop/lint/rescue_exception.rb

@@ -18,6 +18,17 @@ def on_resbody(node)
         def targets_exception?(rescue_arg_node)
           Util.const_name(rescue_arg_node) == 'Exception'
         end
+
+        def autocorrect(node)
+          @corrections << lambda do |corrector|
+            corrector.remove(
+              range_with_surrounding_space(
+                node.children.first.children.first.loc.expression,
+                :left
+              )
+            )
+          end
+        end
       end
     end
   end

spec/rubocop/cop/lint/rescue_exception_spec.rb

@@ -120,4 +120,40 @@
                     'end'])
     expect(cop.offenses).to be_empty
   end
+
+  context 'without exception capture' do
+    let(:source) do
+      ['begin',
+       'rescue Exception',
+       'end']
+    end
+
+    let(:corrected_source) do
+      ['begin', # rubocop:disable WordArray
+       'rescue',
+       'end'].join("\n")
+    end
+
+    it 'autocorrects by unspecifying the exception class' do
+      expect(autocorrect_source(cop, source)).to eq(corrected_source)
+    end
+  end
+
+  context 'with exception capture' do
+    let(:source) do
+      ['begin',
+       'rescue Exception => e',
+       'end']
+    end
+
+    let(:corrected_source) do
+      ['begin',
+       'rescue => e',
+       'end'].join("\n")
+    end
+
+    it 'autocorrects by unspecifying the exception class' do
+      expect(autocorrect_source(cop, source)).to eq(corrected_source)
+    end
+  end
 end