Include exception that raised failure in backtrace

lib/rspec/core/formatters/exception_presenter.rb

@@ -31,8 +31,36 @@ def colorized_message_lines(colorizer=::RSpec::Core::Formatters::ConsoleCodes)
           end
         end
 
-        def formatted_backtrace
-          backtrace_formatter.format_backtrace(exception_backtrace, example.metadata)
+        def formatted_backtrace(exception=@exception)
+          backtrace_formatter.format_backtrace((exception.backtrace || []), example.metadata) +
+            formatted_cause(exception)
+        end
+
+        if RSpec::Support::RubyFeatures.supports_exception_cause?
+          def formatted_cause(exception)
+            last_cause = final_exception(exception)
+            cause = []
+
+            if exception.cause
+              cause << '------------------'
+              cause << '--- Caused by: ---'
+              cause << "#{exception_class_name(last_cause)}:" unless exception_class_name(last_cause) =~ /RSpec/
+
+              encoded_string(last_cause.message.to_s).split("\n").each do |line|
+                cause << "  #{line}"
+              end
+
+              cause << ("  #{backtrace_formatter.format_backtrace(last_cause.backtrace, example.metadata).first}")
+            end
+
+            cause
+          end
+        else
+          # :nocov:
+          def formatted_cause(_)
+            []
+          end
+          # :nocov:
         end
 
         def colorized_formatted_backtrace(colorizer=::RSpec::Core::Formatters::ConsoleCodes)
@@ -56,6 +84,14 @@ def failure_slash_error_line
 
       private
 
+        def final_exception(exception)
+          if exception.cause
+            final_exception(exception.cause)
+          else
+            exception
+          end
+        end
+
         def description_and_detail(colorizer, indentation)
           detail = detail_formatter.call(example, colorizer, indentation)
           return (description || detail) unless description && detail
@@ -81,7 +117,7 @@ def encoded_string(string)
           # :nocov:
         end
 
-        def exception_class_name
+        def exception_class_name(exception=@exception)
           name = exception.class.name.to_s
           name = "(anonymous error class)" if name == ''
           name

spec/rspec/core/formatters/exception_presenter_spec.rb

@@ -11,6 +11,7 @@ module RSpec::Core
     before do
       allow(example.execution_result).to receive(:exception) { exception }
       example.metadata[:absolute_file_path] = __FILE__
+      allow(exception).to receive(:cause) if RSpec::Support::RubyFeatures.supports_exception_cause?
     end
 
     describe "#fully_formatted" do
@@ -49,9 +50,9 @@ module RSpec::Core
       end
 
       it "allows the caller to specify additional indentation" do
-        presenter = Formatters::ExceptionPresenter.new(exception, example, :indentation => 4)
+        the_presenter = Formatters::ExceptionPresenter.new(exception, example, :indentation => 4)
 
-        expect(presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |    1) Example
           |       Failure/Error: # The failure happened here!#{ encoding_check }
@@ -64,9 +65,9 @@ module RSpec::Core
       it 'passes the indentation on to the `:detail_formatter` lambda so it can align things' do
         detail_formatter = Proc.new { "Some Detail" }
 
-        presenter = Formatters::ExceptionPresenter.new(exception, example, :indentation => 4,
+        the_presenter = Formatters::ExceptionPresenter.new(exception, example, :indentation => 4,
                                                        :detail_formatter => detail_formatter)
-        expect(presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |    1) Example
           |       Some Detail
@@ -78,11 +79,11 @@ module RSpec::Core
       end
 
       it 'allows the caller to omit the description' do
-        presenter = Formatters::ExceptionPresenter.new(exception, example,
+        the_presenter = Formatters::ExceptionPresenter.new(exception, example,
                                                        :detail_formatter => Proc.new { "Detail!" },
                                                        :description_formatter => Proc.new { })
 
-        expect(presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |  1) Detail!
           |     Failure/Error: # The failure happened here!#{ encoding_check }
@@ -93,9 +94,9 @@ module RSpec::Core
       end
 
       it 'allows the failure/error line to be used as the description' do
-        presenter = Formatters::ExceptionPresenter.new(exception, example, :description_formatter => lambda { |p| p.failure_slash_error_line })
+        the_presenter = Formatters::ExceptionPresenter.new(exception, example, :description_formatter => lambda { |p| p.failure_slash_error_line })
 
-        expect(presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |  1) Failure/Error: # The failure happened here!#{ encoding_check }
           |       Boom
@@ -105,13 +106,13 @@ module RSpec::Core
       end
 
       it 'allows a caller to specify extra details that are added to the bottom' do
-        presenter = Formatters::ExceptionPresenter.new(
+        the_presenter = Formatters::ExceptionPresenter.new(
           exception, example, :extra_detail_formatter => lambda do |failure_number, colorizer, indentation|
             "#{indentation}extra detail for failure: #{failure_number}\n"
           end
         )
 
-        expect(presenter.fully_formatted(2)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+        expect(the_presenter.fully_formatted(2)).to eq(<<-EOS.gsub(/^ +\|/, ''))
           |
           |  2) Example
           |     Failure/Error: # The failure happened here!#{ encoding_check }
@@ -121,8 +122,35 @@ module RSpec::Core
           |     extra detail for failure: 2
         EOS
       end
-    end
 
+      let(:the_exception) { instance_double(Exception, :cause => second_exception, :message => "Boom\nBam", :backtrace => [ "#{__FILE__}:#{line_num}"]) }
+
+      let(:second_exception) do
+        instance_double(Exception, :cause => first_exception, :message => "Second\nexception", :backtrace => ["#{__FILE__}:#{__LINE__}"])
+      end
+
+      let(:first_exception) do
+        instance_double(Exception, :cause => nil, :message => "Real\nculprit", :backtrace => ["#{__FILE__}:#{__LINE__}"])
+      end
+
+      it 'includes the first exception that caused the failure', :if => RSpec::Support::RubyFeatures.supports_exception_cause? do
+        the_presenter = Formatters::ExceptionPresenter.new(the_exception, example)
+
+        expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+          |
+          |  1) Example
+          |     Failure/Error: # The failure happened here!#{ encoding_check }
+          |       Boom
+          |       Bam
+          |     # ./spec/rspec/core/formatters/exception_presenter_spec.rb:#{line_num}
+          |     # ------------------
+          |     # --- Caused by: ---
+          |     #   Real
+          |     #   culprit
+          |     #   ./spec/rspec/core/formatters/exception_presenter_spec.rb:133
+        EOS
+      end
+    end
     describe "#read_failed_line" do
       def read_failed_line
         presenter.send(:read_failed_line)

spec/rspec/core/notifications_spec.rb

@@ -18,6 +18,7 @@
   end
 
   it 'provides `colorized_formatted_backtrace`, which formats the backtrace and colorizes it' do
+    allow(exception).to receive(:cause) if RSpec::Support::RubyFeatures.supports_exception_cause?
     allow(RSpec.configuration).to receive(:color_enabled?).and_return(true)
     expect(notification.colorized_formatted_backtrace).to eq(["\e[36m# #{RSpec::Core::Metadata.relative_path(__FILE__)}:#{exception_line}\e[0m"])
   end