* lib/ostruct.rb: Raise RuntimeError when modifying frozen instances

instead of TypeError. Patch by Kenichi Kamiya. [Fixes GH-383]

* test/ostruct/test_ostruct.rb: Added tests for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43402 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/ostruct.rb

@@ -152,7 +152,7 @@ class OpenStruct
     begin
       @modifiable = true
     rescue
-      raise TypeError, "can't modify frozen #{self.class}", caller(3)
+      raise RuntimeError, "can't modify frozen #{self.class}", caller(3)
     end
     @table
   end

test/ostruct/test_ostruct.rb

@@ -46,14 +46,14 @@ class TC_OpenStruct < Test::Unit::TestCase
     o = OpenStruct.new
     o.a = 'a'
     o.freeze
-    assert_raise(TypeError) {o.b = 'b'}
+    assert_raise(RuntimeError) {o.b = 'b'}
     assert_not_respond_to(o, :b)
-    assert_raise(TypeError) {o.a = 'z'}
+    assert_raise(RuntimeError) {o.a = 'z'}
     assert_equal('a', o.a)
     o = OpenStruct.new :a => 42
     def o.frozen?; nil end
     o.freeze
-    assert_raise(TypeError, '[ruby-core:22559]') {o.a = 1764}
+    assert_raise(RuntimeError, '[ruby-core:22559]') {o.a = 1764}
   end
 
   def test_delete_field