Add IORunnable.noop()

Author: garydgregory

src/changes/changes.xml

@@ -102,6 +102,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add BrokenInputStream.Builder.</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add PathUtils.getExtension(Path).</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add ThrottledInputStream.</action>
+      <action dev="ggregory" type="add"                due-to="Gary Gregory">Add IORunnable.noop().</action>
       <!--  UPDATE -->
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Bump commons.bytebuddy.version from 1.14.10 to 1.14.11 #534.</action>
     </release>

src/main/java/org/apache/commons/io/function/Constants.java

@@ -28,6 +28,11 @@ final class Constants {
     @SuppressWarnings("rawtypes")
     static final IOBiConsumer IO_BI_CONSUMER = (t, u) -> {/* No-op */};
 
+    /**
+     * No-op singleton.
+     */
+    static final IORunnable IO_RUNNABLE = () -> {/* No-op */};
+
     /**
      * No-op singleton.
      */

src/main/java/org/apache/commons/io/function/IORunnable.java

@@ -28,6 +28,16 @@
 @FunctionalInterface
 public interface IORunnable {
 
+    /**
+     * Returns the constant no-op runnable.
+     *
+     * @return a constant no-op runnable.
+     * @since 2.16.0
+     */
+    static IORunnable noop() {
+        return Constants.IO_RUNNABLE;
+    }
+
     /**
      * Creates a {@link Runnable} for this instance that throws {@link UncheckedIOException} instead of {@link IOException}.
      *

src/test/java/org/apache/commons/io/function/IORunnableTest.java

@@ -20,6 +20,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
@@ -55,4 +56,11 @@ public void testAsRunnable() throws Exception {
         assertNull(Executors.callable(runnable.asRunnable()).call());
     }
 
+    @SuppressWarnings("cast")
+    @Test
+    public void testNoop() throws IOException {
+        assertTrue(IORunnable.noop() instanceof IORunnable);
+        IORunnable.noop().run();
+    }
+
 }