Added test for uniquifyName.

core/src/test/java/hudson/tasks/test/TestObjectTest.java

 package hudson.tasks.test;
 
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.List;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -16,5 +20,28 @@ public class TestObjectTest {
         Assert.assertFalse(encoded.contains("/"));
         Assert.assertFalse(encoded.contains(":"));
     }
+
+    @Test public void uniquifyName() {
+        for (int i = 0; i < 2; i++) { // different parents
+            final List<TestObject> ts = new ArrayList<TestObject>();
+            for (int j = 0; j < 10; j++) {
+                final String name = "t" + (int) Math.sqrt(j); // partly unique names
+                ts.add(new SimpleCaseResult() {
+                    @Override public String getSafeName() {
+                        return uniquifyName(ts, name);
+                    }
+                });
+            }
+            List<String> names = new ArrayList<String>();
+            for (TestObject t : ts) {
+                names.add(t.getSafeName());
+            }
+            Assert.assertEquals("[t0, t1, t1_2, t1_3, t2, t2_2, t2_3, t2_4, t2_5, t3]", names.toString());
+            Reference<?> r = new WeakReference<Object>(ts.get(4)); // arbitrarily
+            ts.clear();
+            System.gc();
+            Assert.assertNull(r.get());
+        }
+    }
     
 }