add Module#class_eval test

test/t/module.rb

@@ -31,6 +31,22 @@ assert('Module#append_features', '15.2.2.4.10') do
   Test4AppendFeatures2.const_get(:Const4AppendFeatures2) == Test4AppendFeatures2
 end
 
+assert('Module#class_eval', '15.2.2.4.15') do
+  class Test4ClassEval
+    @a = 11
+    @b = 12
+  end
+  Test4ClassEval.class_eval do
+    def method1
+    end
+  end
+  r = Test4ClassEval.instance_methods
+  Test4ClassEval.class_eval{ @a } == 11 and
+  Test4ClassEval.class_eval{ @b } == 12 and
+  r.class == Array and r.include?(:method1)
+end
+
+
 assert('Module#class_variables', '15.2.2.4.19') do
   class Test4ClassVariables1
     @@var1 = 1