--- jsr166/src/test/tck/LinkedListTest.java	2016/11/14 23:57:55	1.43
+++ jsr166/src/test/tck/LinkedListTest.java	2018/04/03 05:49:43	1.47
@@ -10,10 +10,11 @@ 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;
-import junit.framework.TestSuite;
 
 public class LinkedListTest extends JSR166TestCase {
     public static void main(String[] args) {
@@ -23,14 +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(
@@ -43,8 +49,8 @@ public class LinkedListTest extends JSR1
      * Returns a new queue of given size containing consecutive
      * Integers 0 ... n - 1.
      */
-    private LinkedList<Integer> populatedQueue(int n) {
-        LinkedList<Integer> q = new LinkedList<Integer>();
+    private static LinkedList<Integer> populatedQueue(int n) {
+        LinkedList<Integer> q = new LinkedList<>();
         assertTrue(q.isEmpty());
         for (int i = 0; i < n; ++i)
             assertTrue(q.offer(new Integer(i)));