nonEmpty(nullCollection) allowed

Author: fluentfuture

mug/src/main/java/com/google/mu/util/Optionals.java

@@ -102,7 +102,7 @@ public static <T> Set<T> asSet(Optional<? extends T> optional) {
    * @since 8.3
    */
   public static <C extends Collection<?>> Optional<C> nonEmpty(C collection) {
-    return collection.isEmpty() ? Optional.empty() : Optional.of(collection);
+    return optional(collection != null && !collection.isEmpty(), collection);
   }
 
   /**

mug/src/test/java/com/google/mu/util/OptionalsTest.java

@@ -10,6 +10,8 @@
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 
+import java.util.Collection;
+import java.util.List;
 import java.util.Optional;
 import java.util.OptionalDouble;
 import java.util.OptionalInt;
@@ -74,6 +76,11 @@ public class OptionalsTest {
     assertThat(Optionals.asSet(Optional.of(123))).containsExactly(123);
   }
 
+  @Test public void nonEmpty_nullCollection() {
+    List<?> list = null;
+    assertThat(Optionals.nonEmpty(list)).isEmpty();
+  }
+
   @Test public void nonEmpty_emptyCollection() {
     assertThat(Optionals.nonEmpty(asList())).isEmpty();
   }
@@ -269,13 +276,15 @@ public void inOrder_bothStepsArePresent() {
         .ignore(Optionals.class.getMethod("optional", boolean.class, Object.class))
         .ignore(Optionals.class.getMethod("both", Optional.class, Optional.class))
         .ignore(Optionals.class.getMethod("nonEmpty", CharSequence.class))
+        .ignore(Optionals.class.getMethod("nonEmpty", Collection.class))
         .testAllPublicStaticMethods(Optionals.class);
     new NullPointerTester()
         .setDefault(Optional.class, Optional.of("foo"))
         .setDefault(OptionalInt.class, OptionalInt.of(123))
         .setDefault(OptionalLong.class, OptionalLong.of(123))
         .setDefault(OptionalDouble.class, OptionalDouble.of(123))
         .ignore(Optionals.class.getMethod("nonEmpty", CharSequence.class))
+        .ignore(Optionals.class.getMethod("nonEmpty", Collection.class))
         .setDefault(BiOptional.class, BiOptional.of(1, "one"))
         .ignore(Optionals.class.getMethod("optional", boolean.class, Object.class))
         .testAllPublicStaticMethods(Optionals.class);