track wrapped iterator removability in ListIteratorWrapper

src/main/java/org/apache/commons/collections4/iterators/ListIteratorWrapper.java

@@ -74,6 +74,9 @@ public class ListIteratorWrapper<E> implements ResettableListIterator<E> {
     /** Recall whether the wrapped iterator's "cursor" is in such a state as to allow remove() to be called */
     private boolean removeState;
 
+    /** Recall whether the element last returned by the wrapped iterator can still be removed from it */
+    private boolean wrappedRemovable;
+
     /**
      * Constructs a new {@code ListIteratorWrapper} that will wrap
      * the given iterator.
@@ -145,13 +148,15 @@ public E next() throws NoSuchElementException {
 
         if (currentIndex < wrappedIteratorIndex) {
             ++currentIndex;
+            removeState = wrappedRemovable && currentIndex == wrappedIteratorIndex;
             return list.get(currentIndex - 1);
         }
 
         final E retval = iterator.next();
         list.add(retval);
         ++currentIndex;
         ++wrappedIteratorIndex;
+        wrappedRemovable = true;
         removeState = true;
         return retval;
     }
@@ -187,7 +192,7 @@ public E previous() throws NoSuchElementException {
         if (currentIndex == 0) {
             throw new NoSuchElementException();
         }
-        removeState = wrappedIteratorIndex == currentIndex;
+        removeState = wrappedRemovable && wrappedIteratorIndex == currentIndex;
         return list.get(--currentIndex);
     }
 
@@ -228,6 +233,7 @@ public void remove() throws IllegalStateException {
         list.remove(removeIndex);
         currentIndex = removeIndex;
         wrappedIteratorIndex--;
+        wrappedRemovable = false;
         removeState = false;
     }
 
@@ -247,6 +253,7 @@ public void reset()  {
             return;
         }
         currentIndex = 0;
+        removeState = false;
     }
 
     /**

src/test/java/org/apache/commons/collections4/iterators/ListIteratorWrapperTest.java

@@ -180,6 +180,33 @@ public void testRemove() {
 
     }
 
+    @Test
+    void testRemoveAfterReset() {
+        final ResettableListIterator<E> iter = makeObject();
+        iter.next();
+        iter.reset();
+
+        assertThrows(IllegalStateException.class, iter::remove,
+                "ListIteratorWrapper#remove() should fail; must be repositioned after reset()");
+        assertEquals(testArray.length, list1.size());
+    }
+
+    @Test
+    void testRemoveAfterReturningToWrappedPosition() {
+        final ListIterator<E> iter = makeObject();
+        iter.next();
+        iter.next();
+        iter.previous();
+        iter.previous();
+        // read forwards out of the cache until back at the wrapped iterator's position
+        iter.next();
+        final E second = iter.next();
+
+        iter.remove();
+        assertEquals(testArray.length - 1, list1.size());
+        assertFalse(list1.contains(second), "remove() should drop the element last returned by next()");
+    }
+
     @Test
     void testReset() {
         final ResettableListIterator<E> iter = makeObject();