assert_throws

# File lib/test/unit/assertions.rb, line 390
      def assert_throws(expected_symbol, message="", &proc)
        _wrap_assertion do
          assert_instance_of(Symbol, expected_symbol, "assert_throws expects the symbol that should be thrown for its first argument")
          assert_block("Should have passed a block to assert_throws."){block_given?}
          caught = true
          begin
            catch(expected_symbol) do
              proc.call
              caught = false
            end
            full_message = build_message(message, "<?> should have been thrown.", expected_symbol)
            assert_block(full_message){caught}
          rescue NameError, ThreadError => error
            if UncaughtThrow[error.class] !~ error.message
              raise error
            end
            full_message = build_message(message, "<?> expected to be thrown but\n<?> was thrown.", expected_symbol, $1.intern)
            flunk(full_message)
          end
        end
      end