Merge pull request #2019 from argos83/allow_adding_formatter_subclass

Allow adding a subclass of an already added formatter

Author: JonRowe

lib/rspec/core/formatters.rb

@@ -182,7 +182,7 @@ def register(formatter, notifications)
 
     def duplicate_formatter_exists?(new_formatter)
       @formatters.any? do |formatter|
-        formatter.class === new_formatter && formatter.output == new_formatter.output
+        formatter.class == new_formatter.class && formatter.output == new_formatter.output
       end
     end
 

spec/rspec/core/formatters_spec.rb

@@ -137,6 +137,19 @@ module RSpec::Core::Formatters
           }.to change { loader.formatters.length }
         end
       end
+
+      context "When a custom formatter exists" do
+        specific_formatter = RSpec::Core::Formatters::JsonFormatter
+        generic_formatter = specific_formatter.superclass
+
+        before { loader.add generic_formatter, output }
+
+        it "adds a subclass of that formatter for the same output target" do
+          expect {
+            loader.add specific_formatter, output
+          }.to change { loader.formatters.length }
+        end
+      end
     end
 
     describe "#setup_default" do