--- jsr166/src/test/tck/LinkedListTest.java	2017/03/11 18:20:47	1.46
+++ jsr166/src/test/tck/LinkedListTest.java	2018/05/28 21:19:50	1.48
@@ -10,7 +10,9 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.NoSuchElementException;
+import java.util.concurrent.ThreadLocalRandom;
 
 import junit.framework.Test;
 
@@ -22,14 +24,19 @@ public class LinkedListTest extends JSR1
     public static Test suite() {
         class Implementation implements CollectionImplementation {
             public Class<?> klazz() { return LinkedList.class; }
-            public Collection emptyCollection() { return new LinkedList(); }
+            public List emptyCollection() { return new LinkedList(); }
             public Object makeElement(int i) { return i; }
             public boolean isConcurrent() { return false; }
             public boolean permitsNulls() { return true; }
         }
         class SubListImplementation extends Implementation {
-            public Collection emptyCollection() {
-                return new LinkedList().subList(0, 0);
+            public List emptyCollection() {
+                List list = super.emptyCollection();
+                ThreadLocalRandom rnd = ThreadLocalRandom.current();
+                if (rnd.nextBoolean())
+                    list.add(makeElement(rnd.nextInt()));
+                int i = rnd.nextInt(list.size() + 1);
+                return list.subList(i, i);
             }
         }
         return newTestSuite(
@@ -351,9 +358,11 @@ public class LinkedListTest extends JSR1
      */
     public void testToArray() {
         LinkedList q = populatedQueue(SIZE);
-        Object[] o = q.toArray();
-        for (int i = 0; i < o.length; i++)
-            assertSame(o[i], q.poll());
+        Object[] a = q.toArray();
+        assertSame(Object[].class, a.getClass());
+        for (Object o : a)
+            assertSame(o, q.poll());
+        assertTrue(q.isEmpty());
     }
 
     /**
@@ -364,8 +373,9 @@ public class LinkedListTest extends JSR1
         Integer[] ints = new Integer[SIZE];
         Integer[] array = q.toArray(ints);
         assertSame(ints, array);
-        for (int i = 0; i < ints.length; i++)
-            assertSame(ints[i], q.poll());
+        for (Integer o : ints)
+            assertSame(o, q.poll());
+        assertTrue(q.isEmpty());
     }
 
     /**