diff --git a/src/tests/pagemap_unittest.cc b/src/tests/pagemap_unittest.cc
new file mode 100644
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+++ b/src/tests/pagemap_unittest.cc
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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2003, Google Inc.
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// 
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ---
+// Author: Sanjay Ghemawat
+
+#include "config_for_unittests.h"
+#include <stdio.h>
+#include <stdlib.h>
+#if defined HAVE_STDINT_H
+#include <stdint.h>             // to get intptr_t
+#elif defined HAVE_INTTYPES_H
+#include <inttypes.h>           // another place intptr_t might be defined
+#endif
+#include <sys/types.h>
+#include <vector>
+#include "base/logging.h"
+#include "pagemap.h"
+
+using std::vector;
+
+static void Permute(vector<intptr_t>* elements) {
+  if (elements->empty())
+    return;
+  const size_t num_elements = elements->size();
+  for (size_t i = num_elements - 1; i > 0; --i) {
+    const size_t newpos = rand() % (i + 1);
+    const intptr_t tmp = (*elements)[i];   // swap
+    (*elements)[i] = (*elements)[newpos];
+    (*elements)[newpos] = tmp;
+  }
+}
+
+// Note: we leak memory every time a map is constructed, so do not
+// create too many maps.
+
+// Test specified map type
+template <class Type>
+void TestMap(int limit, bool limit_is_below_the_overflow_boundary) {
+  RAW_LOG(INFO, "Running test with %d iterations...\n", limit);
+
+  { // Test sequential ensure/assignment
+    Type map(malloc);
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      map.Ensure(i, 1);
+      map.set(i, (void*)(i+1));
+      CHECK_EQ(map.get(i), (void*)(i+1));
+    }
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      CHECK_EQ(map.get(i), (void*)(i+1));
+    }
+  }
+
+  { // Test bulk Ensure
+    Type map(malloc);
+    map.Ensure(0, limit);
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      map.set(i, (void*)(i+1));
+      CHECK_EQ(map.get(i), (void*)(i+1));
+    }
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      CHECK_EQ(map.get(i), (void*)(i+1));
+    }
+  }
+
+  // Test that we correctly notice overflow
+  {
+    Type map(malloc);
+    CHECK_EQ(map.Ensure(limit, limit+1), limit_is_below_the_overflow_boundary);
+  }
+
+  { // Test randomized accesses
+    srand(301);   // srand isn't great, but it's portable
+    vector<intptr_t> elements;
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) elements.push_back(i);
+    Permute(&elements);
+
+    Type map(malloc);
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      map.Ensure(elements[i], 1);
+      map.set(elements[i], (void*)(elements[i]+1));
+      CHECK_EQ(map.get(elements[i]), (void*)(elements[i]+1));
+    }
+    for (intptr_t i = 0; i < static_cast<intptr_t>(limit); i++) {
+      CHECK_EQ(map.get(i), (void*)(i+1));
+    }
+  }
+}
+
+// REQUIRES: BITS==10, i.e., valid range is [0,1023].
+// Representations for different types will end up being:
+//    PageMap1: array[1024]
+//    PageMap2: array[32][32]
+//    PageMap3: array[16][16][4]
+template <class Type>
+void TestNext(const char* name) {
+  RAW_LOG(ERROR, "Running NextTest %s\n", name);
+  Type map(malloc);
+  char a, b, c, d, e;
+
+  // When map is empty
+  CHECK(map.Next(0) == NULL);
+  CHECK(map.Next(5) == NULL);
+  CHECK(map.Next(1<<30) == NULL);
+
+  // Add a single value
+  map.Ensure(40, 1);
+  map.set(40, &a);
+  CHECK(map.Next(0) == &a);
+  CHECK(map.Next(39) == &a);
+  CHECK(map.Next(40) == &a);
+  CHECK(map.Next(41) == NULL);
+  CHECK(map.Next(1<<30) == NULL);
+
+  // Add a few values
+  map.Ensure(41, 1);
+  map.Ensure(100, 3);
+  map.set(41, &b);
+  map.set(100, &c);
+  map.set(101, &d);
+  map.set(102, &e);
+  CHECK(map.Next(0) == &a);
+  CHECK(map.Next(39) == &a);
+  CHECK(map.Next(40) == &a);
+  CHECK(map.Next(41) == &b);
+  CHECK(map.Next(42) == &c);
+  CHECK(map.Next(63) == &c);
+  CHECK(map.Next(64) == &c);
+  CHECK(map.Next(65) == &c);
+  CHECK(map.Next(99) == &c);
+  CHECK(map.Next(100) == &c);
+  CHECK(map.Next(101) == &d);
+  CHECK(map.Next(102) == &e);
+  CHECK(map.Next(103) == NULL);
+}
+
+int main(int argc, char** argv) {
+  TestMap< TCMalloc_PageMap1<10> > (100, true);
+  TestMap< TCMalloc_PageMap1<10> > (1 << 10, false);
+  TestMap< TCMalloc_PageMap2<20> > (100, true);
+  TestMap< TCMalloc_PageMap2<20> > (1 << 20, false);
+  TestMap< TCMalloc_PageMap3<20> > (100, true);
+  TestMap< TCMalloc_PageMap3<20> > (1 << 20, false);
+
+  TestNext< TCMalloc_PageMap1<10> >("PageMap1");
+  TestNext< TCMalloc_PageMap2<10> >("PageMap2");
+  TestNext< TCMalloc_PageMap3<10> >("PageMap3");
+
+  printf("PASS\n");
+  return 0;
+}