feat: ensure that all data written by MonitoredPipe is ASCII-8BIT encoded

Author: jcouball

lib/process_executer/monitored_pipe.rb

@@ -128,6 +128,13 @@ def initialize(redirection_destination, chunk_size: 100_000)
       @condition_variable = ConditionVariable.new
       @chunk_size = chunk_size
       @pipe_reader, @pipe_writer = IO.pipe
+
+      # Set the encoding of the pipe reader to ASCII_8BIT. This is not strictly
+      # necessary since read_nonblock always returns a String where encoding is
+      # Encoding::ASCII_8BIT, but it is a good practice to explicitly set the
+      # encoding.
+      pipe_reader.set_encoding(Encoding::ASCII_8BIT)
+
       @state = :open
       @thread = start_monitoring_thread
 
@@ -400,6 +407,7 @@ def monitor
     # @return [void]
     # @api private
     def monitor_pipe
+      # read_nonblock always returns a String where encoding is Encoding::ASCII_8BIT
       new_data = pipe_reader.read_nonblock(chunk_size)
       write_data(new_data)
     rescue IO::WaitReadable

spec/process_executer/monitored_pipe_spec.rb

@@ -744,4 +744,28 @@
       end
     end
   end
+
+  describe 'encoding of output' do
+    let(:output_writer) do
+      Class.new do
+        def initialize
+          @data = []
+        end
+
+        attr_reader :data
+
+        def write(new_data)
+          @data << new_data
+        end
+      end.new
+    end
+
+    it 'should write data with BINARY encoding' do
+      monitored_pipe.write('違いを生み出すサンプルテキスト'.encode(Encoding::UTF_8))
+      monitored_pipe.write('이것은 파일이다'.encode(Encoding::UTF_8))
+      monitored_pipe.close
+      expect(output_writer.data.size).to eq(2)
+      expect(output_writer.data).to all(satisfy { |d| d.encoding == Encoding::BINARY })
+    end
+  end
 end