Added example for overriding a pre-existing stub and got it to pass.

lib/rspec/mocks/method_double.rb

@@ -127,14 +127,14 @@ def add_expectation(error_generator, expectation_ordering, expected_from, opts,
       def add_negative_expectation(error_generator, expectation_ordering, expected_from, &implementation)
         configure_method
         expectation = NegativeMessageExpectation.new(error_generator, expectation_ordering, expected_from, @method_name, implementation)
-        expectations << expectation
+        expectations.unshift expectation
         expectation
       end
 
       def add_stub(error_generator, expectation_ordering, expected_from, opts={}, &implementation)
         configure_method
         stub = MessageExpectation.new(error_generator, expectation_ordering, expected_from, @method_name, nil, :any, opts, &implementation)
-        stubs << stub
+        stubs.unshift stub
         stub
       end
 

rspec-mocks.gemspec

@@ -9,7 +9,7 @@ Gem::Specification.new do |s|
 
   s.required_rubygems_version = Gem::Requirement.new("> 1.3.1") if s.respond_to? :required_rubygems_version=
   s.authors = ["David Chelimsky", "Chad Humphries"]
-  s.date = %q{2010-04-04}
+  s.date = %q{2010-04-09}
   s.description = %q{Rspec's 'test double' framework, with support for stubbing and mocking}
   s.email = %q{dchelimsky@gmail.com;chad.humphries@gmail.com}
   s.extra_rdoc_files = [

spec/rspec/mocks/stub_spec.rb

@@ -67,7 +67,7 @@ def existing_instance_method
 
       it "should return values in order to consecutive calls" do
         return_values = ["1",2,Object.new]
-        @instance.stub(:msg).and_return(return_values[0],return_values[1],return_values[2])
+        @instance.stub(:msg).and_return(*return_values)
         @instance.msg.should == return_values[0]
         @instance.msg.should == return_values[1]
         @instance.msg.should == return_values[2]
@@ -130,10 +130,16 @@ def existing_instance_method
         end.should throw_symbol(:up)
       end
 
-      it "should override a pre-existing stub" do
+      it "should override a pre-existing method" do
         @stub.stub(:existing_instance_method).and_return(:updated_stub_value)
         @stub.existing_instance_method.should == :updated_stub_value
       end
+
+      it "should override a pre-existing stub" do
+        @stub.stub(:foo) { 'bar' }
+        @stub.stub(:foo) { 'baz' }
+        @stub.foo.should == 'baz'
+      end
 
       it "should limit " do
         @stub.stub(:foo).with("bar")