diff -r 000000000000 -r 6474c204b198 mfbt/tests/TestRollingMean.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mfbt/tests/TestRollingMean.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,121 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/RollingMean.h"
+
+using mozilla::RollingMean;
+
+class MyClass
+{
+  public:
+    uint32_t value;
+
+    MyClass(uint32_t val = 0) : value(val) {
+    }
+
+    bool operator==(const MyClass& other) const {
+      return value == other.value;
+    }
+
+    MyClass operator+(const MyClass& other) const {
+      return MyClass(value + other.value);
+    }
+
+    MyClass operator-(const MyClass& other) const {
+      return MyClass(value - other.value);
+    }
+
+    MyClass operator/(uint32_t div) const {
+      return MyClass(value / div);
+    }
+};
+
+class RollingMeanSuite
+{
+  public:
+    RollingMeanSuite()
+    { }
+
+    void runTests() {
+      testZero();
+      testClear();
+      testRolling();
+      testClass();
+      testMove();
+    }
+
+  private:
+    void testZero() {
+      RollingMean<uint32_t, uint64_t> mean(3);
+      MOZ_RELEASE_ASSERT(mean.empty());
+    }
+
+    void testClear() {
+      RollingMean<uint32_t, uint64_t> mean(3);
+
+      mean.insert(4);
+      MOZ_RELEASE_ASSERT(mean.mean() == 4);
+
+      mean.clear();
+      MOZ_RELEASE_ASSERT(mean.empty());
+
+      mean.insert(3);
+      MOZ_RELEASE_ASSERT(mean.mean() == 3);
+    }
+
+    void testRolling() {
+      RollingMean<uint32_t, uint64_t> mean(3);
+
+      mean.insert(10);
+      MOZ_RELEASE_ASSERT(mean.mean() == 10);
+
+      mean.insert(20);
+      MOZ_RELEASE_ASSERT(mean.mean() == 15);
+
+      mean.insert(35);
+      MOZ_RELEASE_ASSERT(mean.mean() == 21);
+
+      mean.insert(5);
+      MOZ_RELEASE_ASSERT(mean.mean() == 20);
+
+      mean.insert(10);
+      MOZ_RELEASE_ASSERT(mean.mean() == 16);
+    }
+
+    void testClass() {
+      RollingMean<MyClass, MyClass> mean(3);
+
+      mean.insert(MyClass(4));
+      MOZ_RELEASE_ASSERT(mean.mean() == MyClass(4));
+
+      mean.clear();
+      MOZ_RELEASE_ASSERT(mean.empty());
+    }
+
+    void testMove() {
+      RollingMean<uint32_t, uint64_t> mean(3);
+      mean = RollingMean<uint32_t, uint64_t>(4);
+      MOZ_RELEASE_ASSERT(mean.maxValues() == 4);
+
+      mean.insert(10);
+      MOZ_RELEASE_ASSERT(mean.mean() == 10);
+
+      mean = RollingMean<uint32_t, uint64_t>(3);
+      mean.insert(30);
+      mean.insert(40);
+      mean.insert(50);
+      mean.insert(60);
+      MOZ_RELEASE_ASSERT(mean.mean() == 50);
+    }
+
+};
+
+int main()
+{
+  RollingMeanSuite suite;
+  suite.runTests();
+  return 0;
+}