Add m-esr52 at 52.6.0

1 files changed, 883 insertions, 0 deletions

diff --git a/toolkit/components/telemetry/tests/unit/test_nsITelemetry.js b/toolkit/components/telemetry/tests/unit/test_nsITelemetry.js
new file mode 100644
index 000000000..8dc552604
--- /dev/null
+++ b/toolkit/components/telemetry/tests/unit/test_nsITelemetry.js
@@ -0,0 +1,883 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const INT_MAX = 0x7FFFFFFF;
+
+Cu.import("resource://gre/modules/Services.jsm", this);
+Cu.import("resource://gre/modules/TelemetryUtils.jsm", this);
+
+// Return an array of numbers from lower up to, excluding, upper
+function numberRange(lower, upper)
+{
+  let a = [];
+  for (let i=lower; i<upper; ++i) {
+    a.push(i);
+  }
+  return a;
+}
+
+function expect_fail(f) {
+  let failed = false;
+  try {
+    f();
+    failed = false;
+  } catch (e) {
+    failed = true;
+  }
+  do_check_true(failed);
+}
+
+function expect_success(f) {
+  let succeeded = false;
+  try {
+    f();
+    succeeded = true;
+  } catch (e) {
+    succeeded = false;
+  }
+  do_check_true(succeeded);
+}
+
+function compareHistograms(h1, h2) {
+  let s1 = h1.snapshot();
+  let s2 = h2.snapshot();
+
+  do_check_eq(s1.histogram_type, s2.histogram_type);
+  do_check_eq(s1.min, s2.min);
+  do_check_eq(s1.max, s2.max);
+  do_check_eq(s1.sum, s2.sum);
+
+  do_check_eq(s1.counts.length, s2.counts.length);
+  for (let i = 0; i < s1.counts.length; i++)
+    do_check_eq(s1.counts[i], s2.counts[i]);
+
+  do_check_eq(s1.ranges.length, s2.ranges.length);
+  for (let i = 0; i < s1.ranges.length; i++)
+    do_check_eq(s1.ranges[i], s2.ranges[i]);
+}
+
+function check_histogram(histogram_type, name, min, max, bucket_count) {
+  var h = Telemetry.getHistogramById(name);
+  var r = h.snapshot().ranges;
+  var sum = 0;
+  for (let i=0;i<r.length;i++) {
+    var v = r[i];
+    sum += v;
+    h.add(v);
+  }
+  var s = h.snapshot();
+  // verify properties
+  do_check_eq(sum, s.sum);
+
+  // there should be exactly one element per bucket
+  for (let i of s.counts) {
+    do_check_eq(i, 1);
+  }
+  var hgrams = Telemetry.histogramSnapshots
+  let gh = hgrams[name]
+  do_check_eq(gh.histogram_type, histogram_type);
+
+  do_check_eq(gh.min, min)
+  do_check_eq(gh.max, max)
+
+  // Check that booleans work with nonboolean histograms
+  h.add(false);
+  h.add(true);
+  s = h.snapshot().counts;
+  do_check_eq(s[0], 2)
+  do_check_eq(s[1], 2)
+
+  // Check that clearing works.
+  h.clear();
+  s = h.snapshot();
+  for (var i of s.counts) {
+    do_check_eq(i, 0);
+  }
+  do_check_eq(s.sum, 0);
+
+  h.add(0);
+  h.add(1);
+  var c = h.snapshot().counts;
+  do_check_eq(c[0], 1);
+  do_check_eq(c[1], 1);
+}
+
+// This MUST be the very first test of this file.
+add_task({
+  skip_if: () => gIsAndroid
+},
+function* test_instantiate() {
+  const ID = "TELEMETRY_TEST_COUNT";
+  let h = Telemetry.getHistogramById(ID);
+
+  // Instantiate the subsession histogram through |add| and make sure they match.
+  // This MUST be the first use of "TELEMETRY_TEST_COUNT" in this file, otherwise
+  // |add| will not instantiate the histogram.
+  h.add(1);
+  let snapshot = h.snapshot();
+  let subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.equal(snapshot.sum, subsession[ID].sum,
+               "Histogram and subsession histogram sum must match.");
+  // Clear the histogram, so we don't void the assumptions from the other tests.
+  h.clear();
+});
+
+add_task(function* test_parameterChecks() {
+  let kinds = [Telemetry.HISTOGRAM_EXPONENTIAL, Telemetry.HISTOGRAM_LINEAR]
+  let testNames = ["TELEMETRY_TEST_EXPONENTIAL", "TELEMETRY_TEST_LINEAR"]
+  for (let i = 0; i < kinds.length; i++) {
+    let histogram_type = kinds[i];
+    let test_type = testNames[i];
+    let [min, max, bucket_count] = [1, INT_MAX - 1, 10]
+    check_histogram(histogram_type, test_type, min, max, bucket_count);
+  }
+});
+
+add_task(function* test_noSerialization() {
+  // Instantiate the storage for this histogram and make sure it doesn't
+  // get reflected into JS, as it has no interesting data in it.
+  Telemetry.getHistogramById("NEWTAB_PAGE_PINNED_SITES_COUNT");
+  do_check_false("NEWTAB_PAGE_PINNED_SITES_COUNT" in Telemetry.histogramSnapshots);
+});
+
+add_task(function* test_boolean_histogram() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  var r = h.snapshot().ranges;
+  // boolean histograms ignore numeric parameters
+  do_check_eq(uneval(r), uneval([0, 1, 2]))
+  for (var i=0;i<r.length;i++) {
+    var v = r[i];
+    h.add(v);
+  }
+  h.add(true);
+  h.add(false);
+  var s = h.snapshot();
+  do_check_eq(s.histogram_type, Telemetry.HISTOGRAM_BOOLEAN);
+  // last bucket should always be 0 since .add parameters are normalized to either 0 or 1
+  do_check_eq(s.counts[2], 0);
+  do_check_eq(s.sum, 3);
+  do_check_eq(s.counts[0], 2);
+});
+
+add_task(function* test_flag_histogram() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_FLAG");
+  var r = h.snapshot().ranges;
+  // Flag histograms ignore numeric parameters.
+  do_check_eq(uneval(r), uneval([0, 1, 2]));
+  // Should already have a 0 counted.
+  var c = h.snapshot().counts;
+  var s = h.snapshot().sum;
+  do_check_eq(uneval(c), uneval([1, 0, 0]));
+  do_check_eq(s, 0);
+  // Should switch counts.
+  h.add(1);
+  var c2 = h.snapshot().counts;
+  var s2 = h.snapshot().sum;
+  do_check_eq(uneval(c2), uneval([0, 1, 0]));
+  do_check_eq(s2, 1);
+  // Should only switch counts once.
+  h.add(1);
+  var c3 = h.snapshot().counts;
+  var s3 = h.snapshot().sum;
+  do_check_eq(uneval(c3), uneval([0, 1, 0]));
+  do_check_eq(s3, 1);
+  do_check_eq(h.snapshot().histogram_type, Telemetry.HISTOGRAM_FLAG);
+});
+
+add_task(function* test_count_histogram() {
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_COUNT2");
+  let s = h.snapshot();
+  do_check_eq(uneval(s.ranges), uneval([0, 1, 2]));
+  do_check_eq(uneval(s.counts), uneval([0, 0, 0]));
+  do_check_eq(s.sum, 0);
+  h.add();
+  s = h.snapshot();
+  do_check_eq(uneval(s.counts), uneval([1, 0, 0]));
+  do_check_eq(s.sum, 1);
+  h.add();
+  s = h.snapshot();
+  do_check_eq(uneval(s.counts), uneval([2, 0, 0]));
+  do_check_eq(s.sum, 2);
+});
+
+add_task(function* test_categorical_histogram()
+{
+  let h1 = Telemetry.getHistogramById("TELEMETRY_TEST_CATEGORICAL");
+  for (let v of ["CommonLabel", "Label2", "Label3", "Label3", 0, 0, 1]) {
+    h1.add(v);
+  }
+  for (let s of ["", "Label4", "1234"]) {
+    Assert.throws(() => h1.add(s));
+  }
+
+  let snapshot = h1.snapshot();
+  Assert.equal(snapshot.sum, 6);
+  Assert.deepEqual(snapshot.ranges, [0, 1, 2, 3]);
+  Assert.deepEqual(snapshot.counts, [3, 2, 2, 0]);
+
+  let h2 = Telemetry.getHistogramById("TELEMETRY_TEST_CATEGORICAL_OPTOUT");
+  for (let v of ["CommonLabel", "CommonLabel", "Label4", "Label5", "Label6", 0, 1]) {
+    h2.add(v);
+  }
+  for (let s of ["", "Label3", "1234"]) {
+    Assert.throws(() => h2.add(s));
+  }
+
+  snapshot = h2.snapshot();
+  Assert.equal(snapshot.sum, 7);
+  Assert.deepEqual(snapshot.ranges, [0, 1, 2, 3, 4]);
+  Assert.deepEqual(snapshot.counts, [3, 2, 1, 1, 0]);
+});
+
+add_task(function* test_getHistogramById() {
+  try {
+    Telemetry.getHistogramById("nonexistent");
+    do_throw("This can't happen");
+  } catch (e) {
+
+  }
+  var h = Telemetry.getHistogramById("CYCLE_COLLECTOR");
+  var s = h.snapshot();
+  do_check_eq(s.histogram_type, Telemetry.HISTOGRAM_EXPONENTIAL);
+  do_check_eq(s.min, 1);
+  do_check_eq(s.max, 10000);
+});
+
+add_task(function* test_getSlowSQL() {
+  var slow = Telemetry.slowSQL;
+  do_check_true(("mainThread" in slow) && ("otherThreads" in slow));
+});
+
+add_task(function* test_getWebrtc() {
+  var webrtc = Telemetry.webrtcStats;
+  do_check_true("IceCandidatesStats" in webrtc);
+  var icestats = webrtc.IceCandidatesStats;
+  do_check_true("webrtc" in icestats);
+});
+
+// Check that telemetry doesn't record in private mode
+add_task(function* test_privateMode() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  var orig = h.snapshot();
+  Telemetry.canRecordExtended = false;
+  h.add(1);
+  do_check_eq(uneval(orig), uneval(h.snapshot()));
+  Telemetry.canRecordExtended = true;
+  h.add(1);
+  do_check_neq(uneval(orig), uneval(h.snapshot()));
+});
+
+// Check that telemetry records only when it is suppose to.
+add_task(function* test_histogramRecording() {
+  // Check that no histogram is recorded if both base and extended recording are off.
+  Telemetry.canRecordBase = false;
+  Telemetry.canRecordExtended = false;
+
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTOUT");
+  h.clear();
+  let orig = h.snapshot();
+  h.add(1);
+  Assert.equal(orig.sum, h.snapshot().sum);
+
+  // Check that only base histograms are recorded.
+  Telemetry.canRecordBase = true;
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "Histogram value should have incremented by 1 due to recording.");
+
+  // Extended histograms should not be recorded.
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTIN");
+  orig = h.snapshot();
+  h.add(1);
+  Assert.equal(orig.sum, h.snapshot().sum,
+               "Histograms should be equal after recording.");
+
+  // Runtime created histograms should not be recorded.
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  orig = h.snapshot();
+  h.add(1);
+  Assert.equal(orig.sum, h.snapshot().sum,
+               "Histograms should be equal after recording.");
+
+  // Check that extended histograms are recorded when required.
+  Telemetry.canRecordExtended = true;
+
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "Runtime histogram value should have incremented by 1 due to recording.");
+
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTIN");
+  orig = h.snapshot();
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "Histogram value should have incremented by 1 due to recording.");
+
+  // Check that base histograms are still being recorded.
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTOUT");
+  h.clear();
+  orig = h.snapshot();
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "Histogram value should have incremented by 1 due to recording.");
+});
+
+add_task(function* test_addons() {
+  var addon_id = "testing-addon";
+  var fake_addon_id = "fake-addon";
+  var name1 = "testing-histogram1";
+  var register = Telemetry.registerAddonHistogram;
+  expect_success(() =>
+                 register(addon_id, name1, Telemetry.HISTOGRAM_LINEAR, 1, 5, 6));
+  // Can't register the same histogram multiple times.
+  expect_fail(() =>
+              register(addon_id, name1, Telemetry.HISTOGRAM_LINEAR, 1, 5, 6));
+  // Make sure we can't get at it with another name.
+  expect_fail(() => Telemetry.getAddonHistogram(fake_addon_id, name1));
+
+  // Check for reflection capabilities.
+  var h1 = Telemetry.getAddonHistogram(addon_id, name1);
+  // Verify that although we've created storage for it, we don't reflect it into JS.
+  var snapshots = Telemetry.addonHistogramSnapshots;
+  do_check_false(name1 in snapshots[addon_id]);
+  h1.add(1);
+  h1.add(3);
+  var s1 = h1.snapshot();
+  do_check_eq(s1.histogram_type, Telemetry.HISTOGRAM_LINEAR);
+  do_check_eq(s1.min, 1);
+  do_check_eq(s1.max, 5);
+  do_check_eq(s1.counts[1], 1);
+  do_check_eq(s1.counts[3], 1);
+
+  var name2 = "testing-histogram2";
+  expect_success(() =>
+                 register(addon_id, name2, Telemetry.HISTOGRAM_LINEAR, 2, 4, 4));
+
+  var h2 = Telemetry.getAddonHistogram(addon_id, name2);
+  h2.add(2);
+  h2.add(3);
+  var s2 = h2.snapshot();
+  do_check_eq(s2.histogram_type, Telemetry.HISTOGRAM_LINEAR);
+  do_check_eq(s2.min, 2);
+  do_check_eq(s2.max, 4);
+  do_check_eq(s2.counts[1], 1);
+  do_check_eq(s2.counts[2], 1);
+
+  // Check that we can register histograms for a different addon with
+  // identical names.
+  var extra_addon = "testing-extra-addon";
+  expect_success(() =>
+                 register(extra_addon, name1, Telemetry.HISTOGRAM_BOOLEAN));
+
+  // Check that we can register flag histograms.
+  var flag_addon = "testing-flag-addon";
+  var flag_histogram = "flag-histogram";
+  expect_success(() =>
+                 register(flag_addon, flag_histogram, Telemetry.HISTOGRAM_FLAG));
+  expect_success(() =>
+                 register(flag_addon, name2, Telemetry.HISTOGRAM_LINEAR, 2, 4, 4));
+
+  // Check that we reflect registered addons and histograms.
+  snapshots = Telemetry.addonHistogramSnapshots;
+  do_check_true(addon_id in snapshots)
+  do_check_true(extra_addon in snapshots);
+  do_check_true(flag_addon in snapshots);
+
+  // Check that we have data for our created histograms.
+  do_check_true(name1 in snapshots[addon_id]);
+  do_check_true(name2 in snapshots[addon_id]);
+  var s1_alt = snapshots[addon_id][name1];
+  var s2_alt = snapshots[addon_id][name2];
+  do_check_eq(s1_alt.min, s1.min);
+  do_check_eq(s1_alt.max, s1.max);
+  do_check_eq(s1_alt.histogram_type, s1.histogram_type);
+  do_check_eq(s2_alt.min, s2.min);
+  do_check_eq(s2_alt.max, s2.max);
+  do_check_eq(s2_alt.histogram_type, s2.histogram_type);
+
+  // Even though we've registered it, it shouldn't show up until data is added to it.
+  do_check_false(name1 in snapshots[extra_addon]);
+
+  // Flag histograms should show up automagically.
+  do_check_true(flag_histogram in snapshots[flag_addon]);
+  do_check_false(name2 in snapshots[flag_addon]);
+
+  // Check that we can remove addon histograms.
+  Telemetry.unregisterAddonHistograms(addon_id);
+  snapshots = Telemetry.addonHistogramSnapshots;
+  do_check_false(addon_id in snapshots);
+  // Make sure other addons are unaffected.
+  do_check_true(extra_addon in snapshots);
+});
+
+add_task(function* test_expired_histogram() {
+  var test_expired_id = "TELEMETRY_TEST_EXPIRED";
+  var dummy = Telemetry.getHistogramById(test_expired_id);
+  var rh = Telemetry.registeredHistograms(Ci.nsITelemetry.DATASET_RELEASE_CHANNEL_OPTIN, []);
+  Assert.ok(!!rh);
+
+  dummy.add(1);
+
+  do_check_eq(Telemetry.histogramSnapshots["__expired__"], undefined);
+  do_check_eq(Telemetry.histogramSnapshots[test_expired_id], undefined);
+  do_check_eq(rh[test_expired_id], undefined);
+});
+
+add_task(function* test_keyed_histogram() {
+  // Check that invalid names get rejected.
+
+  let threw = false;
+  try {
+    Telemetry.getKeyedHistogramById("test::unknown histogram", "never", Telemetry.HISTOGRAM_BOOLEAN);
+  } catch (e) {
+    // This should throw as it is an unknown ID
+    threw = true;
+  }
+  Assert.ok(threw, "getKeyedHistogramById should have thrown");
+});
+
+add_task(function* test_keyed_boolean_histogram() {
+  const KEYED_ID = "TELEMETRY_TEST_KEYED_BOOLEAN";
+  let KEYS = numberRange(0, 2).map(i => "key" + (i + 1));
+  KEYS.push("漢語");
+  let histogramBase = {
+    "min": 1,
+    "max": 2,
+    "histogram_type": 2,
+    "sum": 1,
+    "ranges": [0, 1, 2],
+    "counts": [0, 1, 0]
+  };
+  let testHistograms = numberRange(0, 3).map(i => JSON.parse(JSON.stringify(histogramBase)));
+  let testKeys = [];
+  let testSnapShot = {};
+
+  let h = Telemetry.getKeyedHistogramById(KEYED_ID);
+  for (let i=0; i<2; ++i) {
+    let key = KEYS[i];
+    h.add(key, true);
+    testSnapShot[key] = testHistograms[i];
+    testKeys.push(key);
+
+    Assert.deepEqual(h.keys().sort(), testKeys);
+    Assert.deepEqual(h.snapshot(), testSnapShot);
+  }
+
+  h = Telemetry.getKeyedHistogramById(KEYED_ID);
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let key = KEYS[2];
+  h.add(key, false);
+  testKeys.push(key);
+  testSnapShot[key] = testHistograms[2];
+  testSnapShot[key].sum = 0;
+  testSnapShot[key].counts = [1, 0, 0];
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let allSnapshots = Telemetry.keyedHistogramSnapshots;
+  Assert.deepEqual(allSnapshots[KEYED_ID], testSnapShot);
+
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+});
+
+add_task(function* test_keyed_count_histogram() {
+  const KEYED_ID = "TELEMETRY_TEST_KEYED_COUNT";
+  const KEYS = numberRange(0, 5).map(i => "key" + (i + 1));
+  let histogramBase = {
+    "min": 1,
+    "max": 2,
+    "histogram_type": 4,
+    "sum": 0,
+    "ranges": [0, 1, 2],
+    "counts": [1, 0, 0]
+  };
+  let testHistograms = numberRange(0, 5).map(i => JSON.parse(JSON.stringify(histogramBase)));
+  let testKeys = [];
+  let testSnapShot = {};
+
+  let h = Telemetry.getKeyedHistogramById(KEYED_ID);
+  for (let i=0; i<4; ++i) {
+    let key = KEYS[i];
+    let value = i*2 + 1;
+
+    for (let k=0; k<value; ++k) {
+      h.add(key);
+    }
+    testHistograms[i].counts[0] = value;
+    testHistograms[i].sum = value;
+    testSnapShot[key] = testHistograms[i];
+    testKeys.push(key);
+
+    Assert.deepEqual(h.keys().sort(), testKeys);
+    Assert.deepEqual(h.snapshot(key), testHistograms[i]);
+    Assert.deepEqual(h.snapshot(), testSnapShot);
+  }
+
+  h = Telemetry.getKeyedHistogramById(KEYED_ID);
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let key = KEYS[4];
+  h.add(key);
+  testKeys.push(key);
+  testHistograms[4].counts[0] = 1;
+  testHistograms[4].sum = 1;
+  testSnapShot[key] = testHistograms[4];
+
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let allSnapshots = Telemetry.keyedHistogramSnapshots;
+  Assert.deepEqual(allSnapshots[KEYED_ID], testSnapShot);
+
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+});
+
+add_task(function* test_keyed_flag_histogram() {
+  const KEYED_ID = "TELEMETRY_TEST_KEYED_FLAG";
+  let h = Telemetry.getKeyedHistogramById(KEYED_ID);
+
+  const KEY = "default";
+  h.add(KEY, true);
+
+  let testSnapshot = {};
+  testSnapshot[KEY] = {
+    "min": 1,
+    "max": 2,
+    "histogram_type": 3,
+    "sum": 1,
+    "ranges": [0, 1, 2],
+    "counts": [0, 1, 0]
+  };
+
+  Assert.deepEqual(h.keys().sort(), [KEY]);
+  Assert.deepEqual(h.snapshot(), testSnapshot);
+
+  let allSnapshots = Telemetry.keyedHistogramSnapshots;
+  Assert.deepEqual(allSnapshots[KEYED_ID], testSnapshot);
+
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+});
+
+add_task(function* test_keyed_histogram_recording() {
+  // Check that no histogram is recorded if both base and extended recording are off.
+  Telemetry.canRecordBase = false;
+  Telemetry.canRecordExtended = false;
+
+  const TEST_KEY = "record_foo";
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT");
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 0);
+
+  // Check that only base histograms are recorded.
+  Telemetry.canRecordBase = true;
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+               "The keyed histogram should record the correct value.");
+
+  // Extended set keyed histograms should not be recorded.
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTIN");
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 0,
+               "The keyed histograms should not record any data.");
+
+  // Check that extended histograms are recorded when required.
+  Telemetry.canRecordExtended = true;
+
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+                  "The runtime keyed histogram should record the correct value.");
+
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTIN");
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+               "The keyed histogram should record the correct value.");
+
+  // Check that base histograms are still being recorded.
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT");
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1);
+});
+
+add_task(function* test_histogram_recording_enabled() {
+  Telemetry.canRecordBase = true;
+  Telemetry.canRecordExtended = true;
+
+  // Check that a "normal" histogram respects recording-enabled on/off
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_COUNT");
+  var orig = h.snapshot();
+
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+              "add should record by default.");
+
+  // Check that when recording is disabled - add is ignored
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_COUNT", false);
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+              "When recording is disabled add should not record.");
+
+  // Check that we're back to normal after recording is enabled
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_COUNT", true);
+  h.add(1);
+  Assert.equal(orig.sum + 2, h.snapshot().sum,
+               "When recording is re-enabled add should record.");
+
+  // Check that we're correctly accumulating values other than 1.
+  h.clear();
+  h.add(3);
+  Assert.equal(3, h.snapshot().sum, "Recording counts greater than 1 should work.");
+
+  // Check that a histogram with recording disabled by default behaves correctly
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_COUNT_INIT_NO_RECORD");
+  orig = h.snapshot();
+
+  h.add(1);
+  Assert.equal(orig.sum, h.snapshot().sum,
+               "When recording is disabled by default, add should not record by default.");
+
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_COUNT_INIT_NO_RECORD", true);
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "When recording is enabled add should record.");
+
+  // Restore to disabled
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_COUNT_INIT_NO_RECORD", false);
+  h.add(1);
+  Assert.equal(orig.sum + 1, h.snapshot().sum,
+               "When recording is disabled add should not record.");
+});
+
+add_task(function* test_keyed_histogram_recording_enabled() {
+  Telemetry.canRecordBase = true;
+  Telemetry.canRecordExtended = true;
+
+  // Check RecordingEnabled for keyed histograms which are recording by default
+  const TEST_KEY = "record_foo";
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT");
+
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+    "Keyed histogram add should record by default");
+
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT", false);
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+    "Keyed histogram add should not record when recording is disabled");
+
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT", true);
+  h.clear();
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+    "Keyed histogram add should record when recording is re-enabled");
+
+  // Check that a histogram with recording disabled by default behaves correctly
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_COUNT_INIT_NO_RECORD");
+  h.clear();
+
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 0,
+    "Keyed histogram add should not record by default for histograms which don't record by default");
+
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_KEYED_COUNT_INIT_NO_RECORD", true);
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+    "Keyed histogram add should record when recording is enabled");
+
+  // Restore to disabled
+  Telemetry.setHistogramRecordingEnabled("TELEMETRY_TEST_KEYED_COUNT_INIT_NO_RECORD", false);
+  h.add(TEST_KEY, 1);
+  Assert.equal(h.snapshot(TEST_KEY).sum, 1,
+    "Keyed histogram add should not record when recording is disabled");
+});
+
+add_task(function* test_datasets() {
+  // Check that datasets work as expected.
+
+  const RELEASE_CHANNEL_OPTOUT = Ci.nsITelemetry.DATASET_RELEASE_CHANNEL_OPTOUT;
+  const RELEASE_CHANNEL_OPTIN  = Ci.nsITelemetry.DATASET_RELEASE_CHANNEL_OPTIN;
+
+  // Histograms should default to the extended dataset
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_FLAG");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTIN);
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_FLAG");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTIN);
+
+  // Check test histograms with explicit dataset definitions
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTIN");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTIN);
+  h = Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTOUT");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTOUT);
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTIN");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTIN);
+  h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT");
+  Assert.equal(h.dataset(), RELEASE_CHANNEL_OPTOUT);
+
+  // Check that registeredHistogram works properly
+  let registered = Telemetry.registeredHistograms(RELEASE_CHANNEL_OPTIN, []);
+  registered = new Set(registered);
+  Assert.ok(registered.has("TELEMETRY_TEST_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_RELEASE_OPTIN"));
+  Assert.ok(registered.has("TELEMETRY_TEST_RELEASE_OPTOUT"));
+  registered = Telemetry.registeredHistograms(RELEASE_CHANNEL_OPTOUT, []);
+  registered = new Set(registered);
+  Assert.ok(!registered.has("TELEMETRY_TEST_FLAG"));
+  Assert.ok(!registered.has("TELEMETRY_TEST_RELEASE_OPTIN"));
+  Assert.ok(registered.has("TELEMETRY_TEST_RELEASE_OPTOUT"));
+
+  // Check that registeredKeyedHistograms works properly
+  registered = Telemetry.registeredKeyedHistograms(RELEASE_CHANNEL_OPTIN, []);
+  registered = new Set(registered);
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT"));
+  registered = Telemetry.registeredKeyedHistograms(RELEASE_CHANNEL_OPTOUT, []);
+  registered = new Set(registered);
+  Assert.ok(!registered.has("TELEMETRY_TEST_KEYED_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT"));
+});
+
+add_task({
+  skip_if: () => gIsAndroid
+},
+function* test_subsession() {
+  const ID = "TELEMETRY_TEST_COUNT";
+  const FLAG = "TELEMETRY_TEST_FLAG";
+  let h = Telemetry.getHistogramById(ID);
+  let flag = Telemetry.getHistogramById(FLAG);
+
+  // Both original and duplicate should start out the same.
+  h.clear();
+  let snapshot = Telemetry.histogramSnapshots;
+  let subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.ok(!(ID in snapshot));
+  Assert.ok(!(ID in subsession));
+
+  // They should instantiate and pick-up the count.
+  h.add(1);
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.ok(ID in snapshot);
+  Assert.ok(ID in subsession);
+  Assert.equal(snapshot[ID].sum, 1);
+  Assert.equal(subsession[ID].sum, 1);
+
+  // They should still reset properly.
+  h.clear();
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.ok(!(ID in snapshot));
+  Assert.ok(!(ID in subsession));
+
+  // Both should instantiate and pick-up the count.
+  h.add(1);
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.equal(snapshot[ID].sum, 1);
+  Assert.equal(subsession[ID].sum, 1);
+
+  // Check that we are able to only reset the duplicate histogram.
+  h.clear(true);
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.ok(ID in snapshot);
+  Assert.ok(ID in subsession);
+  Assert.equal(snapshot[ID].sum, 1);
+  Assert.equal(subsession[ID].sum, 0);
+
+  // Both should register the next count.
+  h.add(1);
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.equal(snapshot[ID].sum, 2);
+  Assert.equal(subsession[ID].sum, 1);
+
+  // Retrieve a subsession snapshot and pass the flag to
+  // clear subsession histograms too.
+  h.clear();
+  flag.clear();
+  h.add(1);
+  flag.add(1);
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms(true);
+  Assert.ok(ID in snapshot);
+  Assert.ok(ID in subsession);
+  Assert.ok(FLAG in snapshot);
+  Assert.ok(FLAG in subsession);
+  Assert.equal(snapshot[ID].sum, 1);
+  Assert.equal(subsession[ID].sum, 1);
+  Assert.equal(snapshot[FLAG].sum, 1);
+  Assert.equal(subsession[FLAG].sum, 1);
+
+  // The next subsesssion snapshot should show the histograms
+  // got reset.
+  snapshot = Telemetry.histogramSnapshots;
+  subsession = Telemetry.snapshotSubsessionHistograms();
+  Assert.ok(ID in snapshot);
+  Assert.ok(ID in subsession);
+  Assert.ok(FLAG in snapshot);
+  Assert.ok(FLAG in subsession);
+  Assert.equal(snapshot[ID].sum, 1);
+  Assert.equal(subsession[ID].sum, 0);
+  Assert.equal(snapshot[FLAG].sum, 1);
+  Assert.equal(subsession[FLAG].sum, 0);
+});
+
+add_task({
+  skip_if: () => gIsAndroid
+},
+function* test_keyed_subsession() {
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_FLAG");
+  const KEY = "foo";
+
+  // Both original and subsession should start out the same.
+  h.clear();
+  Assert.ok(!(KEY in h.snapshot()));
+  Assert.ok(!(KEY in h.subsessionSnapshot()));
+  Assert.equal(h.snapshot(KEY).sum, 0);
+  Assert.equal(h.subsessionSnapshot(KEY).sum, 0);
+
+  // Both should register the flag.
+  h.add(KEY, 1);
+  Assert.ok(KEY in h.snapshot());
+  Assert.ok(KEY in h.subsessionSnapshot());
+  Assert.equal(h.snapshot(KEY).sum, 1);
+  Assert.equal(h.subsessionSnapshot(KEY).sum, 1);
+
+  // Check that we are able to only reset the subsession histogram.
+  h.clear(true);
+  Assert.ok(KEY in h.snapshot());
+  Assert.ok(!(KEY in h.subsessionSnapshot()));
+  Assert.equal(h.snapshot(KEY).sum, 1);
+  Assert.equal(h.subsessionSnapshot(KEY).sum, 0);
+
+  // Setting the flag again should make both match again.
+  h.add(KEY, 1);
+  Assert.ok(KEY in h.snapshot());
+  Assert.ok(KEY in h.subsessionSnapshot());
+  Assert.equal(h.snapshot(KEY).sum, 1);
+  Assert.equal(h.subsessionSnapshot(KEY).sum, 1);
+
+  // Check that "snapshot and clear" works properly.
+  let snapshot = h.snapshot();
+  let subsession = h.snapshotSubsessionAndClear();
+  Assert.ok(KEY in snapshot);
+  Assert.ok(KEY in subsession);
+  Assert.equal(snapshot[KEY].sum, 1);
+  Assert.equal(subsession[KEY].sum, 1);
+
+  subsession = h.subsessionSnapshot();
+  Assert.ok(!(KEY in subsession));
+  Assert.equal(h.subsessionSnapshot(KEY).sum, 0);
+});