Ensure sc.close() is executed before FixedChannelPoolTest.testCloseAsync() returns (netty#9298)

Motivation:

We observed some test-failues sometimes in the CI which happened if sc.close() was not completed before the next test did run. If this happened we would fail the bind(...) as the LocalAddress was still in use.

Modifications:

Await the close before return

Result:

Fixes race in testsuite which resulted in FixedChannelPoolTest.testAcquireNewConnection to fail if FixedChannelPoolTest.testCloseAsync() did run before it.

Author: normanmaurer

transport/src/test/java/io/netty/channel/pool/FixedChannelPoolTest.java

@@ -20,6 +20,7 @@
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
+import io.netty.channel.ChannelPromise;
 import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
@@ -374,13 +375,15 @@ public void initChannel(LocalChannel ch) throws Exception {
         pool.acquire().get();
         pool.acquire().get();
 
+        final ChannelPromise closePromise = sc.newPromise();
         pool.closeAsync().addListener(new GenericFutureListener<Future<? super Void>>() {
             @Override
             public void operationComplete(Future<? super Void> future) throws Exception {
                 Assert.assertEquals(0, pool.acquiredChannelCount());
-                sc.close().syncUninterruptibly();
+                sc.close(closePromise).syncUninterruptibly();
             }
         }).awaitUninterruptibly();
+        closePromise.awaitUninterruptibly();
     }
 
     private static final class TestChannelPoolHandler extends AbstractChannelPoolHandler {