Merge pull request #237 from rspec/non-pass-through-exceptions

Define module we can use to safely rescue most exceptions.

Author: xaviershay

lib/rspec/support.rb

@@ -118,6 +118,17 @@ def self.warning_notifier
       @warning_notifier ||= DEFAULT_WARNING_NOTIFIER
     end
 
+    # @private
+    module AllExceptionsExceptOnesWeMustNotRescue
+      # These exceptions are dangerous to rescue as rescuing them
+      # would interfere with things we should not interfere with.
+      AVOID_RESCUING = [NoMemoryError, SignalException, Interrupt, SystemExit]
+
+      def self.===(exception)
+        AVOID_RESCUING.none? { |ar| ar === exception }
+      end
+    end
+
     # The Differ is only needed when a a spec fails with a diffable failure.
     # In the more common case of all specs passing or the only failures being
     # non-diffable, we can avoid the extra cost of loading the differ, diff-lcs,

spec/rspec/support_spec.rb

@@ -207,5 +207,42 @@ def append_to_array_instead_of_warning
         }.to append_to_array_instead_of_warning
       end
     end
+
+    describe Support::AllExceptionsExceptOnesWeMustNotRescue do
+      it "rescues a StandardError" do
+        expect {
+          begin
+            raise StandardError
+          rescue subject
+          end
+        }.not_to raise_error
+      end
+
+      it 'rescues an Exception' do
+        expect {
+          begin
+            raise Exception
+          rescue subject
+          end
+        }.not_to raise_error
+      end
+
+      Support::AllExceptionsExceptOnesWeMustNotRescue::AVOID_RESCUING.each do |klass|
+        exception = if klass == SignalException
+                      SignalException.new("INT")
+                    else
+                      klass
+                    end
+
+        it "does not rescue a #{klass}" do
+          expect {
+            begin
+              raise exception
+            rescue subject
+            end
+          }.to raise_error(klass)
+        end
+      end
+    end
   end
 end