Fix condition and fix test to catch that broken condition

Author: eregon

lib/timeout.rb

@@ -72,7 +72,7 @@ def initialize
     end
 
     if defined?(Ractor.store_if_absent) &&
-       defined?(Ractor.shareble?) && Ractor.shareable?(GET_TIME)
+       defined?(Ractor.shareable?) && Ractor.shareable?(GET_TIME)
 
        # Ractor support if
        # 1. Ractor.store_if_absent is available
@@ -85,8 +85,6 @@ def initialize
        def self.instance
          Ractor[:timeout_gem_state]
        end
-
-       ::Timeout::RACTOR_SUPPORT = true # for test
     else
       GLOBAL_STATE = State.new
 

test/test_timeout.rb

@@ -299,5 +299,5 @@ def test_ractor
 
       assert_equal :ok, r
     end;
-  end if Timeout.const_defined?(:RACTOR_SUPPORT)
+  end if defined?(::Ractor) && RUBY_VERSION >= '4.0'
 end