More detailed error message when and_raise gets a class whose constru…

…ctor requires 1 or more args.

- #99, #100.

lib/rspec/mocks/message_expectation.rb

@@ -179,9 +179,12 @@ def invoke(*args, &block)
 
         begin
           begin
-            Kernel::raise(@exception_to_raise) unless @exception_to_raise.nil?
-          rescue ArgumentError => ex
-            Kernel::raise ex.exception("Errors raised by expectations cannot have constructors that take arguments. #{@exception_to_raise.to_s} has a constructor requiring #{@exception_to_raise.instance_method(:initialize).arity}.")
+            raise(@exception_to_raise) unless @exception_to_raise.nil?
+          rescue ArgumentError => e
+            raise e.exception(<<-MESSAGE)
+'and_raise' can only accept an Exception class if an instance can be constructed with no arguments.
+#{@exception_to_raise.to_s}'s initialize method requires #{@exception_to_raise.instance_method(:initialize).arity} arguments, so you have to supply an instance instead.
+MESSAGE
           end
           Kernel::throw(*@args_to_throw) unless @args_to_throw.empty?
 

spec/rspec/mocks/mock_spec.rb

@@ -216,16 +216,16 @@ def @mock.method_with_default_argument(arg={}); end
         }.should raise_error(RuntimeError, "error message")
       end
 
-      it "fails with nice message if passed Exception requires constructor arguments" do
-        class ErrorThatHasAConstructorTakingArguments < RuntimeError
+      it "fails with helpful message if submitted Exception requires constructor arguments" do
+        class ErrorWithNonZeroArgConstructor < RuntimeError
           def initialize(i_take_an_argument)
           end
         end
 
-        @mock.should_receive(:something).and_raise(ErrorThatHasAConstructorTakingArguments)
+        @mock.stub(:something).and_raise(ErrorWithNonZeroArgConstructor)
         lambda {
           @mock.something
-        }.should raise_error(ArgumentError, "Errors raised by expectations cannot have constructors that take arguments. RSpec::Mocks::ErrorThatHasAConstructorTakingArguments has a constructor requiring 1.")
+        }.should raise_error(ArgumentError, /^'and_raise' can only accept an Exception class if an instance/)
       end
 
       it "raises RuntimeError with passed message" do