Review usages of defined?

Author: eregon

lib/concurrent-ruby/concurrent/thread_safe/synchronized_delegator.rb

@@ -2,49 +2,46 @@
 require 'monitor'
 
 module Concurrent
-  unless defined?(SynchronizedDelegator)
-
-    # This class provides a trivial way to synchronize all calls to a given object
-    # by wrapping it with a `Delegator` that performs `Monitor#enter/exit` calls
-    # around the delegated `#send`. Example:
-    #
-    #   array = [] # not thread-safe on many impls
-    #   array = SynchronizedDelegator.new([]) # thread-safe
-    #
-    # A simple `Monitor` provides a very coarse-grained way to synchronize a given
-    # object, in that it will cause synchronization for methods that have no need
-    # for it, but this is a trivial way to get thread-safety where none may exist
-    # currently on some implementations.
-    #
-    # This class is currently being considered for inclusion into stdlib, via
-    # https://bugs.ruby-lang.org/issues/8556
-    #
-    # @!visibility private
-    class SynchronizedDelegator < SimpleDelegator
-      def setup
-        @old_abort = Thread.abort_on_exception
-        Thread.abort_on_exception = true
-      end
+  # This class provides a trivial way to synchronize all calls to a given object
+  # by wrapping it with a `Delegator` that performs `Monitor#enter/exit` calls
+  # around the delegated `#send`. Example:
+  #
+  #   array = [] # not thread-safe on many impls
+  #   array = SynchronizedDelegator.new([]) # thread-safe
+  #
+  # A simple `Monitor` provides a very coarse-grained way to synchronize a given
+  # object, in that it will cause synchronization for methods that have no need
+  # for it, but this is a trivial way to get thread-safety where none may exist
+  # currently on some implementations.
+  #
+  # This class is currently being considered for inclusion into stdlib, via
+  # https://bugs.ruby-lang.org/issues/8556
+  #
+  # @!visibility private
+  class SynchronizedDelegator < SimpleDelegator
+    def setup
+      @old_abort = Thread.abort_on_exception
+      Thread.abort_on_exception = true
+    end
 
-      def teardown
-        Thread.abort_on_exception = @old_abort
-      end
+    def teardown
+      Thread.abort_on_exception = @old_abort
+    end
 
-      def initialize(obj)
-        __setobj__(obj)
-        @monitor = Monitor.new
-      end
+    def initialize(obj)
+      __setobj__(obj)
+      @monitor = Monitor.new
+    end
 
-      def method_missing(method, *args, &block)
-        monitor = @monitor
-        begin
-          monitor.enter
-          super
-        ensure
-          monitor.exit
-        end
+    def method_missing(method, *args, &block)
+      monitor = @monitor
+      begin
+        monitor.enter
+        super
+      ensure
+        monitor.exit
       end
-
     end
+
   end
 end

spec/concurrent/atomic/atomic_reference_spec.rb

@@ -180,6 +180,12 @@ module Concurrent
   end
 
   RSpec.describe AtomicReference do
+    if RUBY_ENGINE != 'ruby'
+      it 'does not load the C extension' do
+        expect(defined?(Concurrent::CAtomicReference)).to be_falsey
+      end
+    end
+
     if Concurrent.on_jruby?
       it 'inherits from JavaAtomicReference' do
         expect(described_class.ancestors).to include(Concurrent::JavaAtomicReference)

spec/concurrent/exchanger_spec.rb

@@ -239,7 +239,7 @@ module Concurrent
     end
   end
 
-  if defined? JavaExchanger
+  if Concurrent.on_jruby?
     RSpec.describe JavaExchanger do
       it_behaves_like :exchanger
     end

spec/concurrent/thread_safe/no_unsafe_spec.rb

@@ -1,4 +1,6 @@
-if defined?(JRUBY_VERSION) && ENV['TEST_NO_UNSAFE']
+require 'concurrent/utility/engine'
+
+if Concurrent.on_jruby? && ENV['TEST_NO_UNSAFE']
   # to be used like this: rake test TEST_NO_UNSAFE=true
   load 'test/package.jar'
   java_import 'thread_safe.SecurityManager'