[LANG-1568]

org.apache.commons.lang3.function.FailableConsumer.andThen(FailableConsumer<?
super T, E>)

src/main/java/org/apache/commons/lang3/function/FailableBiFunction.java

@@ -57,7 +57,7 @@ public interface FailableBiFunction<T, U, R, E extends Throwable> {
      * @param after the operation to perform after this one.
      * @return a composed {@code FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
      * @throws E Thrown when a consumer fails.
-     * @throws NullPointerException if after is null.
+     * @throws NullPointerException if {@code after} is null.
      */
     default <V> FailableBiFunction<T, U, V, E> andThen(final FailableFunction<? super R, ? extends V, E> after) throws E {
         Objects.requireNonNull(after);

src/main/java/org/apache/commons/lang3/function/FailableConsumer.java

@@ -17,17 +17,33 @@
 
 package org.apache.commons.lang3.function;
 
+import java.util.Objects;
 import java.util.function.Consumer;
 
 /**
  * A functional interface like {@link Consumer} that declares a {@code Throwable}.
  *
- * @param <O> Consumed type 1.
+ * @param <T> Consumed type 1.
  * @param <E> Thrown exception.
  * @since 3.11
  */
 @FunctionalInterface
-public interface FailableConsumer<O, E extends Throwable> {
+public interface FailableConsumer<T, E extends Throwable> {
+
+    /** NOP singleton */
+    @SuppressWarnings("rawtypes")
+    final FailableConsumer NOP = t -> {/* NOP */};
+
+    /**
+     * Returns The NOP singleton.
+     *
+     * @param <T> Consumed type 1.
+     * @param <E> Thrown exception.
+     * @return The NOP singleton.
+     */
+    static <T, E extends Throwable> FailableConsumer<T, E> nop() {
+        return NOP;
+    }
 
     /**
      * Accepts the consumer.
@@ -35,5 +51,21 @@ public interface FailableConsumer<O, E extends Throwable> {
      * @param object the parameter for the consumable to accept
      * @throws E Thrown when the consumer fails.
      */
-    void accept(O object) throws E;
+    void accept(T object) throws E;
+
+    /**
+     * Returns a composed {@code Consumer} like {@link Consumer#andThen(Consumer)}.
+     *
+     * @param after the operation to perform after this operation
+     * @return a composed {@code Consumer} like {@link Consumer#andThen(Consumer)}.
+     * @throws E Thrown when a consumer fails.
+     * @throws NullPointerException if {@code after} is null
+     */
+    default FailableConsumer<T, E> andThen(final FailableConsumer<? super T, E> after) throws E {
+        Objects.requireNonNull(after);
+        return (final T t) -> {
+            accept(t);
+            after.accept(t);
+        };
+    }
 }

src/test/java/org/apache/commons/lang3/function/FailableFunctionsTest.java

@@ -269,7 +269,7 @@ public class FailableFunctionsTest {
     private static final IllegalStateException ILLEGAL_STATE_EXCEPTION = new IllegalStateException();
 
     @Test
-    void testAcceptBiConsumer() {
+    public void testAcceptBiConsumer() {
         final Testable<?, ?> testable = new Testable<>(null);
         Throwable e = assertThrows(IllegalStateException.class,
             () -> Failable.accept(Testable::test, testable, ILLEGAL_STATE_EXCEPTION));
@@ -290,7 +290,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptConsumer() {
+    public void testAcceptConsumer() {
         final Testable<?, ?> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(Testable::test, testable));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -311,7 +311,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptDoubleConsumer() {
+    public void testAcceptDoubleConsumer() {
         final Testable<?, Double> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(testable::testDouble, 1d));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -336,7 +336,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptIntConsumer() {
+    public void testAcceptIntConsumer() {
         final Testable<?, Integer> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(testable::testInt, 1));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -361,7 +361,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptLongConsumer() {
+    public void testAcceptLongConsumer() {
         final Testable<?, Long> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(testable::testLong, 1L));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -386,7 +386,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptObjDoubleConsumer() {
+    public void testAcceptObjDoubleConsumer() {
         final Testable<String, Double> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class,
             () -> Failable.accept(testable::testObjDouble, "X", 1d));
@@ -416,7 +416,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptObjIntConsumer() {
+    public void testAcceptObjIntConsumer() {
         final Testable<String, Integer> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(testable::testObjInt, "X", 1));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -445,7 +445,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAcceptObjLongConsumer() {
+    public void testAcceptObjLongConsumer() {
         final Testable<String, Long> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         Throwable e = assertThrows(IllegalStateException.class, () -> Failable.accept(testable::testObjLong, "X", 1L));
         assertSame(ILLEGAL_STATE_EXCEPTION, e);
@@ -531,7 +531,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAsCallable() {
+    public void testAsCallable() {
         FailureOnOddInvocations.invocations = 0;
         final FailableCallable<FailureOnOddInvocations, SomeException> failableCallable = FailureOnOddInvocations::new;
         final Callable<FailureOnOddInvocations> callable = Failable.asCallable(failableCallable);
@@ -550,7 +550,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAsConsumer() {
+    public void testAsConsumer() {
         final Testable<?, ?> testable = new Testable<>(ILLEGAL_STATE_EXCEPTION);
         final Consumer<Testable<?, ?>> consumer = Failable.asConsumer(Testable::test);
         Throwable e = assertThrows(IllegalStateException.class, () -> consumer.accept(testable));
@@ -572,7 +572,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testAsRunnable() {
+    public void testAsRunnable() {
         FailureOnOddInvocations.invocations = 0;
         final Runnable runnable = Failable.asRunnable(FailureOnOddInvocations::new);
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, runnable::run);
@@ -599,7 +599,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testBiConsumer() throws Throwable {
+    public void testBiConsumer() throws Throwable {
         final Testable<?, ?> testable = new Testable<>(null);
         final FailableBiConsumer<Testable<?, ?>, Throwable, Throwable> failableBiConsumer = (t, th) -> {
             t.setThrowable(th);
@@ -627,7 +627,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testBiConsumerAndThen() throws Throwable {
+    public void testBiConsumerAndThen() throws Throwable {
         final Testable<?, ?> testable = new Testable<>(null);
         final FailableBiConsumer<Testable<?, ?>, Throwable, Throwable> failableBiConsumer = (t, th) -> {
             t.setThrowable(th);
@@ -710,7 +710,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testCallable() {
+    public void testCallable() {
         FailureOnOddInvocations.invocations = 0;
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class,
             () -> Failable.run(FailureOnOddInvocations::new));
@@ -729,6 +729,23 @@ public class FailableFunctionsTest {
         new Functions();
     }
 
+    @Test
+    public void testConsumerAndThen() throws Throwable {
+        final Testable<?, ?> testable = new Testable<>(null);
+        final FailableConsumer<Throwable, Throwable> failableConsumer = (th) -> {
+            testable.setThrowable(th);
+            testable.test();
+        };
+        final FailableConsumer<Throwable, Throwable> nop = FailableConsumer.nop();
+        final Throwable e = assertThrows(OutOfMemoryError.class,
+            () -> nop.andThen(failableConsumer).accept(ERROR));
+        assertSame(ERROR, e);
+        // Does not throw
+        nop.andThen(nop);
+        // Documented in Javadoc edge-case.
+        assertThrows(NullPointerException.class, () -> failableConsumer.andThen(null));
+    }
+
     @Test
     public void testDoublePredicate() throws Throwable {
         FailureOnOddInvocations.invocations = 0;
@@ -920,7 +937,7 @@ public class FailableFunctionsTest {
     }
 
     @Test
-    void testRunnable() {
+    public void testRunnable() {
         FailureOnOddInvocations.invocations = 0;
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class,
             () -> Failable.run(FailureOnOddInvocations::new));
@@ -938,7 +955,7 @@ public class FailableFunctionsTest {
      * Object and Throwable.
      */
     @Test
-    void testThrows_FailableBiConsumer_Object_Throwable() {
+    public void testThrows_FailableBiConsumer_Object_Throwable() {
         new FailableBiConsumer<Object, Object, Throwable>() {
 
             @Override
@@ -953,7 +970,7 @@ public class FailableFunctionsTest {
      * generic test types.
      */
     @Test
-    void testThrows_FailableBiConsumer_String_IOException() {
+    public void testThrows_FailableBiConsumer_String_IOException() {
         new FailableBiConsumer<String, String, IOException>() {
 
             @Override
@@ -969,7 +986,7 @@ public class FailableFunctionsTest {
      * Object and Throwable.
      */
     @Test
-    void testThrows_FailableBiFunction_Object_Throwable() {
+    public void testThrows_FailableBiFunction_Object_Throwable() {
         new FailableBiFunction<Object, Object, Object, Throwable>() {
 
             @Override
@@ -984,7 +1001,7 @@ public class FailableFunctionsTest {
      * generic test types.
      */
     @Test
-    void testThrows_FailableBiFunction_String_IOException() {
+    public void testThrows_FailableBiFunction_String_IOException() {
         new FailableBiFunction<String, String, String, IOException>() {
 
             @Override
@@ -999,7 +1016,7 @@ public class FailableFunctionsTest {
      * Object and Throwable.
      */
     @Test
-    void testThrows_FailableBiPredicate_Object_Throwable() {
+    public void testThrows_FailableBiPredicate_Object_Throwable() {
         new FailableBiPredicate<Object, Object, Throwable>() {
 
             @Override
@@ -1014,7 +1031,7 @@ public class FailableFunctionsTest {
      * generic test types.
      */
     @Test
-    void testThrows_FailableBiPredicate_String_IOException() {
+    public void testThrows_FailableBiPredicate_String_IOException() {
         new FailableBiPredicate<String, String, IOException>() {
 
             @Override
@@ -1061,7 +1078,7 @@ public class FailableFunctionsTest {
      * Object and Throwable.
      */
     @Test
-    void testThrows_FailableCallable_Object_Throwable() {
+    public void testThrows_FailableCallable_Object_Throwable() {
         new FailableCallable<Object, Throwable>() {
 
             @Override
@@ -1076,7 +1093,7 @@ public class FailableFunctionsTest {
      * generic test types.
      */
     @Test
-    void testThrows_FailableCallable_String_IOException() {
+    public void testThrows_FailableCallable_String_IOException() {
         new FailableCallable<String, IOException>() {
 
             @Override
@@ -1091,7 +1108,7 @@ public class FailableFunctionsTest {
      * Object and Throwable.
      */
     @Test
-    void testThrows_FailableConsumer_Object_Throwable() {
+    public void testThrows_FailableConsumer_Object_Throwable() {
         new FailableConsumer<Object, Throwable>() {
 
             @Override
@@ -1107,7 +1124,7 @@ public class FailableFunctionsTest {
      * generic test types.
      */
     @Test
-    void testThrows_FailableConsumer_String_IOException() {
+    public void testThrows_FailableConsumer_String_IOException() {
         new FailableConsumer<String, IOException>() {
 
             @Override