2 files changed, 571 insertions, 0 deletions
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/moz.build b/toolkit/components/resistfingerprinting/tests/gtest/moz.build
new file mode 100644
index 0000000000..dcc6a7e12e
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/tests/gtest/moz.build
@@ -0,0 +1,5 @@
+UNIFIED_SOURCES += [
+    "test_reduceprecision.cpp",
+]
+
+FINAL_LIBRARY = "xul-gtest"
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp b/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp
new file mode 100644
index 0000000000..5d8b598ff0
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp
@@ -0,0 +1,566 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * 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 <math.h>
+
+#include "gtest/gtest.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefService.h"
+#include "nsServiceManagerUtils.h"
+#include "nsRFPService.h"
+
+using namespace mozilla;
+
+// clang-format off
+/*
+   Hello! Are you looking at this file because you got an error you don't understand?
+   Perhaps something that looks like the following?
+
+    toolkit/components/resistfingerprinting/tests/test_reduceprecision.cpp:15: Failure
+      Expected: reduced1
+        Which is: 2064.83
+      To be equal to: reduced2
+        Which is: 2064.83
+
+   "Gosh," you might say, "They sure look equal to me. What the heck is going on here?"
+
+   The answer lies beyond what you can see, in that which you cannot see. One must
+   journey into the depths, the hidden, that which the world fights its hardest to
+   conceal from us.
+
+   Specifically: you need to look at more decimal places. Run the test with:
+       MOZ_LOG="nsResistFingerprinting:5"
+
+   And look for two successive lines similar to the below (the format will probably
+   be different by the time you read this comment):
+      V/nsResistFingerprinting Given: 2064.83384599999999, Reciprocal Rounding with 50000.00000000000000, Intermediate: 103241692.00000000000000, Got: 2064.83383999999978
+      V/nsResistFingerprinting Given: 2064.83383999999978, Reciprocal Rounding with 50000.00000000000000, Intermediate: 103241691.00000000000000, Got: 2064.83381999999983
+
+   Look at the last two values:
+      Got: 2064.83383999999978
+      Got: 2064.83381999999983
+
+   They're supposed to be equal. They're not. But they both round to 2064.83.
+   Good luck and godspeed.
+*/
+// clang-format on
+
+bool setupJitter(bool enabled) {
+  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+
+  bool jitterEnabled = false;
+  if (prefs) {
+    prefs->GetBoolPref(
+        "privacy.resistFingerprinting.reduceTimerPrecision.jitter",
+        &jitterEnabled);
+    prefs->SetBoolPref(
+        "privacy.resistFingerprinting.reduceTimerPrecision.jitter", enabled);
+  }
+
+  return jitterEnabled;
+}
+
+void cleanupJitter(bool jitterWasEnabled) {
+  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+  if (prefs) {
+    prefs->SetBoolPref(
+        "privacy.resistFingerprinting.reduceTimerPrecision.jitter",
+        jitterWasEnabled);
+  }
+}
+
+void process(double clock, nsRFPService::TimeScale clockUnits,
+             double precision) {
+  double reduced1 = nsRFPService::ReduceTimePrecisionImpl(
+      clock, clockUnits, precision, -1, TimerPrecisionType::Normal);
+  double reduced2 = nsRFPService::ReduceTimePrecisionImpl(
+      reduced1, clockUnits, precision, -1, TimerPrecisionType::Normal);
+  ASSERT_EQ(reduced1, reduced2);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Assumptions)
+{
+  ASSERT_EQ(FLT_RADIX, 2);
+  ASSERT_EQ(DBL_MANT_DIG, 53);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Reciprocal)
+{
+  bool jitterEnabled = setupJitter(false);
+  // This one has a rounding error in the Reciprocal case:
+  process(2064.8338460, nsRFPService::TimeScale::MicroSeconds, 20);
+  // These are just big values
+  process(1516305819, nsRFPService::TimeScale::MicroSeconds, 20);
+  process(69053.12, nsRFPService::TimeScale::MicroSeconds, 20);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_KnownGood)
+{
+  bool jitterEnabled = setupJitter(false);
+  process(2064.8338460, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(69027.62, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(69053.12, nsRFPService::TimeScale::MilliSeconds, 20);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_KnownBad)
+{
+  bool jitterEnabled = setupJitter(false);
+  process(1054.842405, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(273.53038600000002, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(628.66686500000003, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(521.28919100000007, nsRFPService::TimeScale::MilliSeconds, 20);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Edge)
+{
+  bool jitterEnabled = setupJitter(false);
+  process(2611.14, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(2611.16, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(2612.16, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(2601.64, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(2595.16, nsRFPService::TimeScale::MilliSeconds, 20);
+  process(2578.66, nsRFPService::TimeScale::MilliSeconds, 20);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Expectations)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.14, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.145, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.141, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15999, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.13, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 2611.12);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Expectations_HighRes)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.14, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.145, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.141, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15999, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.13, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 2611.12);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Expectations_RFP)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.14, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.145, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.141, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15999, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.13, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 2611.12);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_Expectations_DangerouslyNone)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.14, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.14);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.145, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.145);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.141, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.141);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15999, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.15999);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.15, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.15);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      2611.13, nsRFPService::TimeScale::MilliSeconds, 20, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 2611.13);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_ExpectedLossOfPrecision)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  // We lose integer precision at 9007199254740992 - let's confirm that.
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740992.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 9007199254740990.0);
+  // 9007199254740995 is approximated to 9007199254740996
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740995.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 9007199254740996);
+  // 9007199254740999 is approximated as 9007199254741000
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740999.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 9007199254741000.0);
+  // 9007199254743568 can be represented exactly, but will be clamped to
+  // 9007199254743564
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254743568.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 9007199254743564.0);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_ExpectedLossOfPrecision_HighRes)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  // We lose integer precision at 9007199254740992 - let's confirm that.
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740992.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 9007199254740980.0);
+  // 9007199254740995 is approximated to 9007199254740980
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740995.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 9007199254740980);
+  // 9007199254740999 is approximated as 9007199254741000
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740999.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 9007199254741000.0);
+  // 9007199254743568 can be represented exactly, but will be clamped to
+  // 9007199254743560
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254743568.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::UnconditionalAKAHighRes);
+  ASSERT_EQ(result, 9007199254743560.0);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_ExpectedLossOfPrecision_RFP)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  // We lose integer precision at 9007199254740992 - let's confirm that.
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740992.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 9007199254740990.0);
+  // 9007199254740995 is approximated to 9007199254740980
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740995.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 9007199254740995);
+  // 9007199254740999 is approximated as 9007199254741000
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740999.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 9007199254741000.0);
+  // 9007199254743568 can be represented exactly, but will be clamped to
+  // 9007199254743560
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254743568.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::RFP);
+  ASSERT_EQ(result, 9007199254743565.0);
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting,
+     ReducePrecision_ExpectedLossOfPrecision_DangerouslyNone)
+{
+  bool jitterEnabled = setupJitter(false);
+  double result;
+  // We lose integer precision at 9007199254740992 - let's confirm that.
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740992.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 9007199254740992.0);
+  // 9007199254740995 is approximated to 9007199254740980
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740995.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 9007199254740995);
+  // 9007199254740999 is approximated as 9007199254741000
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254740999.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 9007199254740999.0);
+  // 9007199254743568 can be represented exactly, but will be clamped to
+  // 9007199254743560
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      9007199254743568.0, nsRFPService::TimeScale::MicroSeconds, 5, -1,
+      TimerPrecisionType::DangerouslyNone);
+  ASSERT_EQ(result, 9007199254743568.0);
+  cleanupJitter(jitterEnabled);
+}
+
+// Use an ugly but simple hack to turn an integer-based rand()
+// function to a double-based one.
+#define RAND_DOUBLE (rand() * (rand() / (double)rand()))
+
+// If you're doing logging, you really don't want to run this test.
+#define RUN_AGGRESSIVE false
+
+TEST(ResistFingerprinting, ReducePrecision_Aggressive)
+{
+  if (!RUN_AGGRESSIVE) {
+    return;
+  }
+
+  bool jitterEnabled = setupJitter(false);
+
+  for (int i = 0; i < 10000; i++) {
+    // Test three different time magnitudes, with decimals.
+    // Note that we need separate variables for the different units, as scaling
+    // them after calculating them will erase effects of approximation.
+    // A magnitude in the seconds since epoch range.
+    double time1_s = fmod(RAND_DOUBLE, 1516305819.0);
+    double time1_ms = fmod(RAND_DOUBLE, 1516305819000.0);
+    double time1_us = fmod(RAND_DOUBLE, 1516305819000000.0);
+    // A magnitude in the 'couple of minutes worth of milliseconds' range.
+    double time2_s = fmod(RAND_DOUBLE, (60.0 * 60 * 5));
+    double time2_ms = fmod(RAND_DOUBLE, (1000.0 * 60 * 60 * 5));
+    double time2_us = fmod(RAND_DOUBLE, (1000000.0 * 60 * 60 * 5));
+    // A magnitude in the small range
+    double time3_s = fmod(RAND_DOUBLE, 10);
+    double time3_ms = fmod(RAND_DOUBLE, 10000);
+    double time3_us = fmod(RAND_DOUBLE, 10000000);
+
+    // Test two precision magnitudes, no decimals.
+    // A magnitude in the high milliseconds.
+    double precision1 = rand() % 250000;
+    // a magnitude in the low microseconds.
+    double precision2 = rand() % 200;
+
+    process(time1_s, nsRFPService::TimeScale::Seconds, precision1);
+    process(time1_s, nsRFPService::TimeScale::Seconds, precision2);
+    process(time2_s, nsRFPService::TimeScale::Seconds, precision1);
+    process(time2_s, nsRFPService::TimeScale::Seconds, precision2);
+    process(time3_s, nsRFPService::TimeScale::Seconds, precision1);
+    process(time3_s, nsRFPService::TimeScale::Seconds, precision2);
+
+    process(time1_ms, nsRFPService::TimeScale::MilliSeconds, precision1);
+    process(time1_ms, nsRFPService::TimeScale::MilliSeconds, precision2);
+    process(time2_ms, nsRFPService::TimeScale::MilliSeconds, precision1);
+    process(time2_ms, nsRFPService::TimeScale::MilliSeconds, precision2);
+    process(time3_ms, nsRFPService::TimeScale::MilliSeconds, precision1);
+    process(time3_ms, nsRFPService::TimeScale::MilliSeconds, precision2);
+
+    process(time1_us, nsRFPService::TimeScale::MicroSeconds, precision1);
+    process(time1_us, nsRFPService::TimeScale::MicroSeconds, precision2);
+    process(time2_us, nsRFPService::TimeScale::MicroSeconds, precision1);
+    process(time2_us, nsRFPService::TimeScale::MicroSeconds, precision2);
+    process(time3_us, nsRFPService::TimeScale::MicroSeconds, precision1);
+    process(time3_us, nsRFPService::TimeScale::MicroSeconds, precision2);
+  }
+  cleanupJitter(jitterEnabled);
+}
+
+TEST(ResistFingerprinting, ReducePrecision_JitterTestVectors)
+{
+  bool jitterEnabled = setupJitter(true);
+
+  // clang-format off
+  /*
+   * Here's our test vector. We set the secret to the 16 byte value
+   * 0x0001020304050607 0x1011121314151617
+   *
+   * We then use a stand alone XOrShift128+ generator:
+   *
+   * The midpoints are:
+   *   0    = 328
+   *   500  = 25
+   *   1000 = 73
+   *   1500 = 89
+   *   2000 = 73
+   *   2500 = 153
+   *   3000 = 9
+   *   3500 = 89
+   *   4000 = 73
+   *   4500 = 205
+   *   5000 = 253
+   *   5500 = 141
+   */
+  // clang-format on
+
+  // Set the secret
+  long long throwAway;
+  uint8_t hardcodedSecret[16] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05,
+                                 0x06, 0x07, 0x10, 0x11, 0x12, 0x13,
+                                 0x14, 0x15, 0x16, 0x17};
+
+  nsRFPService::RandomMidpoint(0, 500, -1, &throwAway, hardcodedSecret);
+
+  // Run the test vectors
+  double result;
+
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      1, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 0);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      184, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 0);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      185, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      329, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      499, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      500, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      520, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      524, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      525, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 1000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      930, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 1000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      1072, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 1000);
+
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4000, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4050, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4072, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4073, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4340, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4499, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4500, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4536, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4704, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 4500);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4705, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 5000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      4726, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 5000);
+  result = nsRFPService::ReduceTimePrecisionImpl(
+      5106, nsRFPService::TimeScale::MicroSeconds, 500, 4000,
+      TimerPrecisionType::Normal);
+  ASSERT_EQ(result, 5000);
+
+  cleanupJitter(jitterEnabled);
+}