Fix failing channel tests on JRuby

Author: pitr-ch

spec/concurrent/channel/buffered_channel_spec.rb

@@ -53,9 +53,10 @@ module Concurrent
 
       describe '#pop' do
         it 'should block if buffer is empty' do
-          t = Thread.new { channel.pop }
-          sleep(0.05)
-          expect(t.status).to eq 'sleep'
+          event = Event.new
+          Thread.new { channel.pop; event.set }
+          expect(event.wait(0.1)).to eq false
+          channel.push true
         end
 
         it 'returns value if buffer is not empty' do

spec/concurrent/channel/unbuffered_channel_spec.rb

@@ -19,9 +19,10 @@ module Concurrent
 
         describe '#pop' do
           it 'should block' do
-            t = Thread.new { channel.pop }
-            sleep(0.05)
-            expect(t.status).to eq 'sleep'
+            event = Event.new
+            Thread.new { channel.pop; event.set }
+            expect(event.wait(0.1)).to eq false
+            channel.push true
           end
         end