--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/test/hotspot/gtest/gc/z/test_zBitMap.cpp	2018-06-08 19:47:00.516470001 +0200
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * ORACLE PROPRIETARY/CONFIDENTIAL.  Use is subject to license terms.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zBitMap.inline.hpp"
+#include "unittest.hpp"
+
+class ZBitMapTest : public ::testing::Test {
+protected:
+  static void test_set_pair_unset(size_t size, bool finalizable) {
+    ZBitMap bitmap(size);
+
+    for (BitMap::idx_t i = 0; i < size - 1; i++) {
+      if ((i + 1) % BitsPerWord == 0) {
+        // Can't set pairs of bits in different words.
+        continue;
+      }
+
+      // ZBitMaps are not cleared when constructed.
+      bitmap.clear();
+
+      bool inc_live = false;
+
+      bool ret = bitmap.par_set_bit_pair(i, finalizable, inc_live);
+      EXPECT_TRUE(ret) << "Failed to set bit";
+      EXPECT_TRUE(inc_live) << "Should have set inc_live";
+
+      // First bit should always be set
+      EXPECT_TRUE(bitmap.at(i)) << "Should be set";
+
+      // Second bit should only be set when marking strong
+      EXPECT_NE(bitmap.at(i + 1), finalizable);
+    }
+  }
+
+  static void test_set_pair_set(size_t size, bool finalizable) {
+    ZBitMap bitmap(size);
+
+    for (BitMap::idx_t i = 0; i < size - 1; i++) {
+      if ((i + 1) % BitsPerWord == 0) {
+        // Can't set pairs of bits in different words.
+        continue;
+      }
+
+      // Fill the bitmap with ones.
+      bitmap.set_range(0, size);
+
+      bool inc_live = false;
+
+      bool ret = bitmap.par_set_bit_pair(i, finalizable, inc_live);
+      EXPECT_FALSE(ret) << "Should not succeed setting bit";
+      EXPECT_FALSE(inc_live) << "Should not have set inc_live";
+
+      // Both bits were pre-set.
+      EXPECT_TRUE(bitmap.at(i)) << "Should be set";
+      EXPECT_TRUE(bitmap.at(i + 1)) << "Should be set";
+    }
+  }
+
+  static void test_set_pair_set(bool finalizable) {
+    test_set_pair_set(2,   finalizable);
+    test_set_pair_set(62,  finalizable);
+    test_set_pair_set(64,  finalizable);
+    test_set_pair_set(66,  finalizable);
+    test_set_pair_set(126, finalizable);
+    test_set_pair_set(128, finalizable);
+  }
+
+  static void test_set_pair_unset(bool finalizable) {
+    test_set_pair_unset(2,   finalizable);
+    test_set_pair_unset(62,  finalizable);
+    test_set_pair_unset(64,  finalizable);
+    test_set_pair_unset(66,  finalizable);
+    test_set_pair_unset(126, finalizable);
+    test_set_pair_unset(128, finalizable);
+  }
+
+};
+
+TEST_F(ZBitMapTest, test_set_pair_set) {
+  test_set_pair_set(false);
+  test_set_pair_set(true);
+}
+
+TEST_F(ZBitMapTest, test_set_pair_unset) {
+  test_set_pair_unset(false);
+  test_set_pair_unset(true);
+}