Merge branch '__rultor'

src/main/java/org/cactoos/list/ListIteratorNoNulls.java

@@ -33,8 +33,6 @@
  *
  * @param <T> Element type
  * @since 0.39
- * @todo #1247:30min Add also some null checks both to the `set` and
- *  the `add` methods, then also add some tests to validate this behaviour.
  */
 public final class ListIteratorNoNulls<T> implements ListIterator<T> {
 
@@ -97,11 +95,21 @@ public void remove() {
 
     @Override
     public void set(final T item) {
+        if (item == null) {
+            throw new IllegalArgumentException(
+                "Item can't be NULL in #set(T)"
+            );
+        }
         this.listiterator.set(item);
     }
 
     @Override
     public void add(final T item) {
+        if (item == null) {
+            throw new IllegalArgumentException(
+                "Item can't be NULL in #add(T)"
+            );
+        }
         this.listiterator.add(item);
     }
 

src/test/java/org/cactoos/list/ListIteratorNoNullsTest.java

@@ -135,4 +135,38 @@ void mustSetValueListIterator() {
             new ScalarHasValue<>(4)
         ).affirm();
     }
+
+    @Test
+    void mustThrowsErrorIfAddANullItem() {
+        new Assertion<>(
+            "must throw error if add a null item",
+            () -> {
+                new ListIteratorNoNulls<>(
+                    new ListOf<>(1, 2, 3).listIterator()
+                ).add(null);
+                return 0;
+            },
+            new Throws<>(
+                "Item can't be NULL in #add(T)",
+                IllegalArgumentException.class
+            )
+        ).affirm();
+    }
+
+    @Test
+    void mustThrowsErrorIfSetANullItem() {
+        new Assertion<>(
+            "must throw error if set a null item",
+            () -> {
+                new ListIteratorNoNulls<>(
+                    new ListOf<>(1, 2, 3).listIterator()
+                ).set(null);
+                return 0;
+            },
+            new Throws<>(
+                "Item can't be NULL in #set(T)",
+                IllegalArgumentException.class
+            )
+        ).affirm();
+    }
 }