Update some tests for the new message format of NoMethodError

test/ruby/test_module.rb

@@ -3281,7 +3281,7 @@ class TestModule < Test::Unit::TestCase
       methods = singleton_class.private_instance_methods(false)
       assert_include(methods, :#{method}, ":#{method} should be private")
 
-      assert_raise_with_message(NoMethodError, "private method `#{method}' called for main:Object") {
+      assert_raise_with_message(NoMethodError, /^private method `#{method}' called for /) {
         recv = self
         recv.#{method}
       }

test/ruby/test_nomethod_error.rb

@@ -85,7 +85,7 @@ class TestNoMethodError < Test::Unit::TestCase
     bug3237 = '[ruby-core:29948]'
     str = "\u2600"
     id = :"\u2604"
-    msg = "undefined method `#{id}' for \"#{str}\":String"
+    msg = "undefined method `#{id}' for an instance of String"
     assert_raise_with_message(NoMethodError, Regexp.compile(Regexp.quote(msg)), bug3237) do
       str.__send__(id)
     end