Replace invalid bytes in exception message with '?'

Author: bf4

lib/rspec/core/notifications.rb

@@ -220,12 +220,26 @@ def exception_class_name
         name
       end
 
+      def exception_message
+        @exception_message ||= begin
+          if String.method_defined?(:encoding)
+            exception.message.to_s.
+            # Converting it to a higher higher character set (UTF-16) and then
+            # back (to UTF-8) ensures that you will strip away invalid or undefined byte sequences.
+            encode(::Encoding::UTF_16LE, :invalid => :replace, :undef => :replace, :replace => '?').
+            encode(::Encoding::UTF_8)
+          else
+            exception.message.to_s
+          end
+        end
+      end
+
       def failure_lines
         @failure_lines ||=
           begin
             lines = ["Failure/Error: #{read_failed_line.strip}"]
             lines << "#{exception_class_name}:" unless exception_class_name =~ /RSpec/
-            exception.message.to_s.split("\n").each do |line|
+            exception_message.split("\n").each do |line|
               lines << "  #{line}" if exception.message
             end
             lines

spec/rspec/core/encoding_spec.rb

@@ -15,8 +15,9 @@
 
   describe '#message_lines' do
     let(:message_with_invalid_byte_sequence) do
-      "\xEF \255 \xAD".force_encoding(Encoding::UTF_8)
+      "\xEF \255 \xAD I have bad bytes".force_encoding(Encoding::UTF_8)
     end
+    let(:expected_message) { "? ? ? I have bad bytes" }
     let(:exception) do
       instance_double(
         Exception,
@@ -38,8 +39,10 @@
     end
 
     context "when failure_lines contains an invalid byte sequence" do
-      it "raises an ArgumentError" do
-        expect { lines = notification.message_lines }.to raise_error(ArgumentError)
+      it "replaces bad bytes with a '?'" do
+        lines = notification.message_lines
+        expect(lines[0]).to match %r{\AFailure\/Error}
+        expect(lines[1].strip).to eq(expected_message)
       end
     end