8254692: (se) Clarify the behaviour of the non-abstract SelectorProvider::inheritedChannel

Reviewed-by: chegar, bpb, alanb

src/java.base/share/classes/java/nio/channels/spi/SelectorProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -301,6 +301,9 @@ public abstract class SelectorProvider {
      * returned. Subsequent invocations of this method return the same
      * channel. </p>
      *
+     * @implSpec The default implementation of this method returns
+     * {@code null}.
+     *
      * @return  The inherited channel, if any, otherwise {@code null}.
      *
      * @throws  IOException

test/jdk/java/nio/channels/etc/ProtocolFamilies.java

@@ -22,7 +22,6 @@
  */
 
 import jdk.test.lib.NetworkConfiguration;
-import jdk.test.lib.Platform;
 import jdk.test.lib.net.IPSupport;
 import org.testng.annotations.BeforeTest;
 import org.testng.annotations.DataProvider;
@@ -31,11 +30,8 @@ import org.testng.Assert.ThrowingRunnable;
 import java.io.IOException;
 import java.net.*;
 import java.nio.channels.*;
-import java.nio.channels.spi.AbstractSelector;
 import java.nio.channels.spi.SelectorProvider;
 import static java.lang.System.out;
-import static java.lang.System.getProperty;
-import static java.lang.Boolean.parseBoolean;
 import static java.net.StandardProtocolFamily.INET;
 import static java.net.StandardProtocolFamily.INET6;
 import static jdk.test.lib.net.IPSupport.*;
@@ -305,26 +301,6 @@ public class ProtocolFamilies {
         assertThrows(UOE, () -> SelectorProvider.provider().openDatagramChannel(BAD_PF));
     }
 
-    // A concrete subclass of SelectorProvider, in order to test implSpec
-    static final SelectorProvider customerSelectorProvider = new SelectorProvider() {
-        @Override public DatagramChannel openDatagramChannel() { return null; }
-        @Override public DatagramChannel openDatagramChannel(ProtocolFamily family) { return null; }
-        @Override public Pipe openPipe() { return null; }
-        @Override public AbstractSelector openSelector() { return null; }
-        @Override public ServerSocketChannel openServerSocketChannel() { return null; }
-        @Override public SocketChannel openSocketChannel() { return null; }
-    };
-
-    // Tests the specified default implementation of SelectorProvider
-    @Test
-    public void testCustomProvider() {
-        assertThrows(NPE, () -> customerSelectorProvider.openSocketChannel(null));
-        assertThrows(NPE, () -> customerSelectorProvider.openServerSocketChannel(null));
-
-        assertThrows(UOE, () -> customerSelectorProvider.openSocketChannel(BAD_PF));
-        assertThrows(UOE, () -> customerSelectorProvider.openServerSocketChannel(BAD_PF));
-    }
-
     // Helper methods
 
     private static SocketChannel openSC(StandardProtocolFamily family)

test/jdk/java/nio/channels/spi/SelectorProvider/TestDefaultImplementation.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8254692
+ * @summary Basic test for java.nio.channels.spi.SelectorProvider.java default implementation
+ * @run testng TestDefaultImplementation
+ */
+
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+import java.net.ProtocolFamily;
+import java.nio.channels.*;
+import java.nio.channels.spi.AbstractSelector;
+import java.nio.channels.spi.SelectorProvider;
+
+import static org.testng.Assert.assertNull;
+import static org.testng.Assert.assertThrows;
+
+public class TestDefaultImplementation {
+    static final Class<UnsupportedOperationException> UOE = UnsupportedOperationException.class;
+    static final Class<NullPointerException> NPE = NullPointerException.class;
+    static final ProtocolFamily BAD_PF = () -> "BAD_PROTOCOL_FAMILY";
+
+    @Test
+    public void testSelectorProvider() throws IOException {
+        CustomSelectorProviderImpl customSpi = new CustomSelectorProviderImpl();
+
+        assertNull(customSpi.inheritedChannel());
+
+        assertThrows(NPE, () -> customSpi.openSocketChannel(null));
+        assertThrows(NPE, () -> customSpi.openServerSocketChannel(null));
+
+        assertThrows(UOE, () -> customSpi.openSocketChannel(BAD_PF));
+        assertThrows(UOE, () -> customSpi.openServerSocketChannel(BAD_PF));
+    }
+
+    // A concrete subclass of SelectorProvider, in order to test the
+    // default java.nio.channels.spi.SelectorProvider implementation
+    static class CustomSelectorProviderImpl extends SelectorProvider {
+        @Override public DatagramChannel openDatagramChannel() { return null; }
+        @Override public DatagramChannel openDatagramChannel(ProtocolFamily family) { return null; }
+        @Override public Pipe openPipe() { return null; }
+        @Override public AbstractSelector openSelector() { return null; }
+        @Override public ServerSocketChannel openServerSocketChannel() { return null; }
+        @Override public SocketChannel openSocketChannel() { return null; }
+    }
+}