Call super in Formatter.close methods to ensure sync is reset

lib/rspec/core/formatters/base_formatter.rb

@@ -23,6 +23,7 @@ class BaseFormatter
         def initialize(output)
           @output = output || StringIO.new
           @example_group = nil
+          @sync_started = false
         end
 
         # @api public
@@ -54,16 +55,23 @@ def close(_notification)
       private
 
         def start_sync_output
-          @old_sync, output.sync = output.sync, true if output_supports_sync
+          if output_supports_sync
+            @sync_started = true
+            @old_sync, output.sync = output.sync, true
+          end
         end
 
         def restore_sync_output
-          output.sync = @old_sync if output_supports_sync && !output.closed?
+          output.sync = @old_sync if sync_started? && !output.closed?
         end
 
         def output_supports_sync
           output.respond_to?(:sync=)
         end
+
+        def sync_started?
+          @sync_started
+        end
       end
     end
   end

lib/rspec/core/formatters/base_text_formatter.rb

@@ -63,11 +63,11 @@ def seed(notification)
         #
         # @param _notification [NullNotification] (Ignored)
         def close(_notification)
-          return if output.closed?
-
-          output.puts
-
-          output.flush
+          unless output.closed?
+            output.puts
+            output.flush
+          end
+          super
         end
       end
     end

lib/rspec/core/formatters/json_formatter.rb

@@ -55,6 +55,7 @@ def seed(notification)
 
         def close(_notification)
           output.write @output_hash.to_json
+          super
         end
 
         def dump_profile(profile)

spec/rspec/core/formatters/base_text_formatter_spec.rb

@@ -8,6 +8,11 @@
     let(:output_to_close) { File.new("./output_to_close", "w") }
     let(:formatter) { described_class.new(output_to_close) }
 
+    before do
+      # Call `formatter.start` in order to initialize `@old_sync` before using in `BaseFormatter#close`
+      formatter.start(RSpec::Core::Notifications::StartNotification.new({:count => 1}))
+    end
+
     after do
       # Windows appears to not let the `:isolated_directory` shared group
       # cleanup if the file isn't closed.
@@ -30,6 +35,15 @@
       formatter.close(RSpec::Core::Notifications::NullNotification)
       expect(output_to_close.closed?).to be(false)
     end
+
+    it "restores the output's sync setting" do
+      if !output_to_close.respond_to?(:sync=)
+        skip "output_to_close does not support sync, so closing the formatter will not reset it"
+      end
+      expect {
+        formatter.close(RSpec::Core::Notifications::NullNotification)
+      }.to change(output_to_close, :sync).from(true).to(false)
+    end
   end
 
   describe "#dump_summary" do