Fail fast when DefaultChannelPromise is constructed with null as Channel.

Motivation:

We should fail fast when DefaultChannelPromise is constructed with null as Channel as otherwise it will fail with a NPE once we call setSuccess / setFailure.

Modifications:

Add null check and test.

Result:

Fail fast.

transport/src/main/java/io/netty/bootstrap/AbstractBootstrap.java

@@ -313,9 +313,11 @@ public abstract class AbstractBootstrap<B extends AbstractBootstrap<B, C>, C ext
             if (channel != null) {
                 // channel can be null if newChannel crashed (eg SocketException("too many open files"))
                 channel.unsafe().closeForcibly();
+                // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
+                return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t);
             }
             // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
-            return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t);
+            return new DefaultChannelPromise(new FailedChannel(), GlobalEventExecutor.INSTANCE).setFailure(t);
         }
 
         ChannelFuture regFuture = group().register(channel);

transport/src/main/java/io/netty/bootstrap/FailedChannel.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2017 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.bootstrap;
+
+import io.netty.channel.AbstractChannel;
+import io.netty.channel.ChannelConfig;
+import io.netty.channel.ChannelMetadata;
+import io.netty.channel.ChannelOutboundBuffer;
+import io.netty.channel.ChannelPromise;
+import io.netty.channel.DefaultChannelConfig;
+import io.netty.channel.EventLoop;
+
+import java.net.SocketAddress;
+
+final class FailedChannel extends AbstractChannel {
+    private static final ChannelMetadata METADATA = new ChannelMetadata(false);
+    private final ChannelConfig config = new DefaultChannelConfig(this);
+
+    FailedChannel() {
+        super(null);
+    }
+
+    @Override
+    protected AbstractUnsafe newUnsafe() {
+        return new FailedChannelUnsafe();
+    }
+
+    @Override
+    protected boolean isCompatible(EventLoop loop) {
+        return false;
+    }
+
+    @Override
+    protected SocketAddress localAddress0() {
+        return null;
+    }
+
+    @Override
+    protected SocketAddress remoteAddress0() {
+        return null;
+    }
+
+    @Override
+    protected void doBind(SocketAddress localAddress) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    protected void doDisconnect() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    protected void doClose() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    protected void doBeginRead() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    protected void doWrite(ChannelOutboundBuffer in) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public ChannelConfig config() {
+        return config;
+    }
+
+    @Override
+    public boolean isOpen() {
+        return false;
+    }
+
+    @Override
+    public boolean isActive() {
+        return false;
+    }
+
+    @Override
+    public ChannelMetadata metadata() {
+        return METADATA;
+    }
+
+    private final class FailedChannelUnsafe extends AbstractUnsafe {
+        @Override
+        public void connect(SocketAddress remoteAddress, SocketAddress localAddress, ChannelPromise promise) {
+            promise.setFailure(new UnsupportedOperationException());
+        }
+    }
+}

transport/src/main/java/io/netty/channel/DefaultChannelPromise.java

@@ -21,6 +21,8 @@ import io.netty.util.concurrent.EventExecutor;
 import io.netty.util.concurrent.Future;
 import io.netty.util.concurrent.GenericFutureListener;
 
+import static io.netty.util.internal.ObjectUtil.checkNotNull;
+
 /**
  * The default {@link ChannelPromise} implementation.  It is recommended to use {@link Channel#newPromise()} to create
  * a new {@link ChannelPromise} rather than calling the constructor explicitly.
@@ -37,7 +39,7 @@ public class DefaultChannelPromise extends DefaultPromise<Void> implements Chann
      *        the {@link Channel} associated with this future
      */
     public DefaultChannelPromise(Channel channel) {
-        this.channel = channel;
+        this.channel = checkNotNull(channel, "channel");
     }
 
     /**
@@ -48,7 +50,7 @@ public class DefaultChannelPromise extends DefaultPromise<Void> implements Chann
      */
     public DefaultChannelPromise(Channel channel, EventExecutor executor) {
         super(executor);
-        this.channel = channel;
+        this.channel = checkNotNull(channel, "channel");
     }
 
     @Override

transport/src/test/java/io/netty/channel/DefaultChannelPromiseTest.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2017 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.channel;
+
+import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.util.concurrent.ImmediateEventExecutor;
+import org.junit.Test;
+
+public class DefaultChannelPromiseTest {
+
+    @Test(expected = NullPointerException.class)
+    public void testNullChannel() {
+        new DefaultChannelPromise(null);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testChannelWithNullExecutor() {
+        new DefaultChannelPromise(new EmbeddedChannel(), null);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testNullChannelWithExecutor() {
+        new DefaultChannelPromise(null, ImmediateEventExecutor.INSTANCE);
+    }
+}