Handle syntax error in Ripper

Ripper might fail to parse a Ruby source even if the current runtime
parsed it properly, because some versions of JRuby have different
implementation of runtime parser and Ripper parser.

jruby/jruby#2427

So we handle the syntax error in Ripper and fall back to the simple
single line extraction in that case.

Author: yujinakayama

lib/rspec/core/formatters/snippet_extractor.rb

@@ -55,7 +55,7 @@ def expression_lines
             end
 
             source.lines[(line_range.begin - 1)..(line_range.end - 1)]
-          rescue NoExpressionAtLineError
+          rescue SyntaxError, NoExpressionAtLineError
             [self.class.extract_line_at(source.path, beginning_line_number)]
           end
 

lib/rspec/core/source.rb

@@ -26,6 +26,7 @@ def ast
         @ast ||= begin
           require 'ripper'
           sexp = Ripper.sexp(source)
+          raise SyntaxError unless sexp
           Node.new(sexp)
         end
       end

spec/rspec/core/formatters/snippet_extractor_spec.rb

@@ -250,6 +250,24 @@ def another_expression(*)
         end
       end
 
+      context 'when Ripper cannot parse the source', :isolated_directory do
+        let(:file_path) do
+          'invalid_source.rb'
+        end
+
+        let(:line_number) do
+          1
+        end
+
+        before do
+          File.write(file_path, 'invalid_source]')
+        end
+
+        it 'returns the line by falling back to the simple single line extraction' do
+          expect(expression_lines).to eq(['invalid_source]'])
+        end
+      end
+
       context 'when max line count is given' do
         let(:max_line_count) do
           2