Wrap T/U and/or MiniTest assertions in a separate scope from that of the

example.

lib/rspec/rails/adapters.rb

@@ -15,21 +15,47 @@ def teardown(*methods)
           methods.each {|method| after { send method } }
         end
       end
+
+      module InstanceMethods
+        def method_name
+          @example
+        end
+      end
     end
 
     module TestUnitAssertionAdapter
       extend ActiveSupport::Concern
-      def method_name
-        @example
+
+      class AssertionDelegate
+        include Test::Unit::Assertions
       end
 
-      include Test::Unit::Assertions
+      module ClassMethods
+        def assertion_method_names
+          Test::Unit::Assertions.public_instance_methods.select{|m| m.to_s =~ /^assert/} +
+            [:build_message]
+        end
 
-      included do
-        before do
-          @_result = Struct.new(:add_assertion).new
+        def define_assertion_delegators
+          assertion_method_names.each do |m|
+            class_eval <<-CODE
+              def #{m}(*args, &block)
+                assertion_delegate.send :#{m}, *args, &block
+              end
+            CODE
+          end
         end
       end
+
+      module InstanceMethods
+        def assertion_delegate
+          @assertion_delegate ||= AssertionDelegate.new
+        end
+      end
+
+      included do
+        define_assertion_delegators
+      end
     end
   end
 end

spec/rspec/rails/assertion_adapter_spec.rb

@@ -0,0 +1,28 @@
+require "spec_helper"
+
+describe RSpec::Rails::TestUnitAssertionAdapter do
+  include RSpec::Rails::TestUnitAssertionAdapter
+
+  Test::Unit::Assertions.public_instance_methods.select{|m| m.to_s =~ /^assert/}.each do |m|
+    if m.to_s == "assert_equal"
+      it "exposes #{m} to host examples" do
+        assert_equal 3,3
+        expect do
+          assert_equal 3,4
+        end.to raise_error(ActiveSupport::TestCase::Assertion)
+      end
+    else
+      it "exposes #{m} to host examples" do
+        methods.should include(m)
+      end
+    end
+  end
+
+  it "does not expose internal methods of MiniTest" do
+    methods.should_not include("_assertions")
+  end
+
+  it "does not expose MiniTest's message method" do
+    methods.should_not include("message")
+  end
+end