Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2073 insertions, 0 deletions

diff --git a/toolkit/components/telemetry/tests/unit/test_TelemetryHistograms.js b/toolkit/components/telemetry/tests/unit/test_TelemetryHistograms.js
new file mode 100644
index 0000000000..1ac0c76351
--- /dev/null
+++ b/toolkit/components/telemetry/tests/unit/test_TelemetryHistograms.js
@@ -0,0 +1,2073 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const INT_MAX = 0x7fffffff;
+
+// 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 check_histogram(histogram_type, name, min, max, bucket_count) {
+  var h = Telemetry.getHistogramById(name);
+  h.add(0);
+  var s = h.snapshot();
+  Assert.equal(0, s.sum);
+
+  var hgrams = Telemetry.getSnapshotForHistograms("main", false).parent;
+  let gh = hgrams[name];
+  Assert.equal(gh.histogram_type, histogram_type);
+
+  Assert.deepEqual(gh.range, [min, max]);
+
+  // Check that booleans work with nonboolean histograms
+  h.add(false);
+  h.add(true);
+  s = Object.values(h.snapshot().values);
+  Assert.deepEqual(s, [2, 1, 0]);
+
+  // Check that clearing works.
+  h.clear();
+  s = h.snapshot();
+  Assert.deepEqual(s.values, {});
+  Assert.equal(s.sum, 0);
+
+  h.add(0);
+  h.add(1);
+  var c = Object.values(h.snapshot().values);
+  Assert.deepEqual(c, [1, 1, 0]);
+}
+
+// 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.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+    Assert.ok(ID in subsession);
+    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(async 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(async function test_parameterCounts() {
+  let histogramIds = [
+    "TELEMETRY_TEST_EXPONENTIAL",
+    "TELEMETRY_TEST_LINEAR",
+    "TELEMETRY_TEST_FLAG",
+    "TELEMETRY_TEST_CATEGORICAL",
+    "TELEMETRY_TEST_BOOLEAN",
+  ];
+
+  for (let id of histogramIds) {
+    let h = Telemetry.getHistogramById(id);
+    h.clear();
+    h.add();
+    Assert.equal(
+      h.snapshot().sum,
+      0,
+      "Calling add() without a value should only log an error."
+    );
+    h.clear();
+  }
+});
+
+add_task(async function test_parameterCountsKeyed() {
+  let histogramIds = [
+    "TELEMETRY_TEST_KEYED_FLAG",
+    "TELEMETRY_TEST_KEYED_BOOLEAN",
+    "TELEMETRY_TEST_KEYED_EXPONENTIAL",
+    "TELEMETRY_TEST_KEYED_LINEAR",
+  ];
+
+  for (let id of histogramIds) {
+    let h = Telemetry.getKeyedHistogramById(id);
+    h.clear();
+    h.add("key");
+    Assert.deepEqual(
+      h.snapshot(),
+      {},
+      "Calling add('key') without a value should only log an error."
+    );
+    h.clear();
+  }
+});
+
+add_task(async 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");
+  let histograms = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.equal(false, "NEWTAB_PAGE_PINNED_SITES_COUNT" in histograms);
+});
+
+add_task(async function test_boolean_histogram() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  var r = h.snapshot().range;
+  // boolean histograms ignore numeric parameters
+  Assert.deepEqual(r, [1, 2]);
+  h.add(0);
+  h.add(1);
+  h.add(2);
+
+  h.add(true);
+  h.add(false);
+  var s = h.snapshot();
+  Assert.equal(s.histogram_type, Telemetry.HISTOGRAM_BOOLEAN);
+  // last bucket should always be 0 since .add parameters are normalized to either 0 or 1
+  Assert.deepEqual(s.values, { 0: 2, 1: 3, 2: 0 });
+  Assert.equal(s.sum, 3);
+});
+
+add_task(async function test_flag_histogram() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_FLAG");
+  var r = h.snapshot().range;
+  // Flag histograms ignore numeric parameters.
+  Assert.deepEqual(r, [1, 2]);
+  // Should already have a 0 counted.
+  var v = h.snapshot().values;
+  var s = h.snapshot().sum;
+  Assert.deepEqual(v, { 0: 1, 1: 0 });
+  Assert.equal(s, 0);
+  // Should switch counts.
+  h.add(1);
+  var v2 = h.snapshot().values;
+  var s2 = h.snapshot().sum;
+  Assert.deepEqual(v2, { 0: 0, 1: 1, 2: 0 });
+  Assert.equal(s2, 1);
+  // Should only switch counts once.
+  h.add(1);
+  var v3 = h.snapshot().values;
+  var s3 = h.snapshot().sum;
+  Assert.deepEqual(v3, { 0: 0, 1: 1, 2: 0 });
+  Assert.equal(s3, 1);
+  Assert.equal(h.snapshot().histogram_type, Telemetry.HISTOGRAM_FLAG);
+});
+
+add_task(async function test_count_histogram() {
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_COUNT2");
+  let s = h.snapshot();
+  Assert.deepEqual(s.range, [1, 2]);
+  Assert.deepEqual(s.values, {});
+  Assert.equal(s.sum, 0);
+  h.add();
+  s = h.snapshot();
+  Assert.deepEqual(s.values, { 0: 1, 1: 0 });
+  Assert.equal(s.sum, 1);
+  h.add();
+  s = h.snapshot();
+  Assert.deepEqual(s.values, { 0: 2, 1: 0 });
+  Assert.equal(s.sum, 2);
+});
+
+add_task(async 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"]) {
+    // The |add| method should not throw for unexpected values, but rather
+    // print an error message in the console.
+    h1.add(s);
+  }
+
+  let snapshot = h1.snapshot();
+  Assert.equal(snapshot.sum, 6);
+  Assert.deepEqual(snapshot.range, [1, 50]);
+  Assert.deepEqual(snapshot.values, { 0: 3, 1: 2, 2: 2, 3: 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"]) {
+    // The |add| method should not throw for unexpected values, but rather
+    // print an error message in the console.
+    h2.add(s);
+  }
+
+  snapshot = h2.snapshot();
+  Assert.equal(snapshot.sum, 7);
+  Assert.deepEqual(snapshot.range, [1, 50]);
+  Assert.deepEqual(snapshot.values, { 0: 3, 1: 2, 2: 1, 3: 1, 4: 0 });
+
+  // This histogram overrides the default of 50 values to 70.
+  let h3 = Telemetry.getHistogramById("TELEMETRY_TEST_CATEGORICAL_NVALUES");
+  for (let v of ["CommonLabel", "Label7", "Label8"]) {
+    h3.add(v);
+  }
+
+  snapshot = h3.snapshot();
+  Assert.equal(snapshot.sum, 3);
+  Assert.deepEqual(snapshot.range, [1, 70]);
+  Assert.deepEqual(snapshot.values, { 0: 1, 1: 1, 2: 1, 3: 0 });
+});
+
+add_task(async function test_getCategoricalLabels() {
+  let h = Telemetry.getCategoricalLabels();
+
+  Assert.deepEqual(h.TELEMETRY_TEST_CATEGORICAL, [
+    "CommonLabel",
+    "Label2",
+    "Label3",
+  ]);
+  Assert.deepEqual(h.TELEMETRY_TEST_CATEGORICAL_OPTOUT, [
+    "CommonLabel",
+    "Label4",
+    "Label5",
+    "Label6",
+  ]);
+  Assert.deepEqual(h.TELEMETRY_TEST_CATEGORICAL_NVALUES, [
+    "CommonLabel",
+    "Label7",
+    "Label8",
+  ]);
+  Assert.deepEqual(h.TELEMETRY_TEST_KEYED_CATEGORICAL, [
+    "CommonLabel",
+    "Label2",
+    "Label3",
+  ]);
+});
+
+add_task(async function test_add_error_behaviour() {
+  const PLAIN_HISTOGRAMS_TO_TEST = [
+    "TELEMETRY_TEST_FLAG",
+    "TELEMETRY_TEST_EXPONENTIAL",
+    "TELEMETRY_TEST_LINEAR",
+    "TELEMETRY_TEST_BOOLEAN",
+  ];
+
+  const KEYED_HISTOGRAMS_TO_TEST = [
+    "TELEMETRY_TEST_KEYED_FLAG",
+    "TELEMETRY_TEST_KEYED_COUNT",
+    "TELEMETRY_TEST_KEYED_BOOLEAN",
+  ];
+
+  // Check that |add| doesn't throw for plain histograms.
+  for (let hist of PLAIN_HISTOGRAMS_TO_TEST) {
+    const returnValue =
+      Telemetry.getHistogramById(hist).add("unexpected-value");
+    Assert.strictEqual(
+      returnValue,
+      undefined,
+      "Adding to an histogram must return 'undefined'."
+    );
+  }
+
+  // And for keyed histograms.
+  for (let hist of KEYED_HISTOGRAMS_TO_TEST) {
+    const returnValue = Telemetry.getKeyedHistogramById(hist).add(
+      "some-key",
+      "unexpected-value"
+    );
+    Assert.strictEqual(
+      returnValue,
+      undefined,
+      "Adding to a keyed histogram must return 'undefined'."
+    );
+  }
+});
+
+add_task(async function test_API_return_values() {
+  // Check that the plain scalar functions don't allow to crash the browser.
+  // We expect 'undefined' to be returned so that .add(1).add() can't be called.
+  // See bug 1321349 for context.
+  let hist = Telemetry.getHistogramById("TELEMETRY_TEST_LINEAR");
+  let keyedHist = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_COUNT");
+
+  const RETURN_VALUES = [
+    hist.clear(),
+    hist.add(1),
+    keyedHist.clear(),
+    keyedHist.add("some-key", 1),
+  ];
+
+  for (let returnValue of RETURN_VALUES) {
+    Assert.strictEqual(
+      returnValue,
+      undefined,
+      "The function must return undefined"
+    );
+  }
+});
+
+add_task(async 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();
+  Assert.equal(s.histogram_type, Telemetry.HISTOGRAM_EXPONENTIAL);
+  Assert.deepEqual(s.range, [1, 10000]);
+});
+
+add_task(async function test_getSlowSQL() {
+  var slow = Telemetry.slowSQL;
+  Assert.ok("mainThread" in slow && "otherThreads" in slow);
+});
+
+// Check that telemetry doesn't record in private mode
+add_task(async function test_privateMode() {
+  var h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  var orig = h.snapshot();
+  Telemetry.canRecordExtended = false;
+  h.add(1);
+  Assert.deepEqual(orig, h.snapshot());
+  Telemetry.canRecordExtended = true;
+  h.add(1);
+  Assert.notDeepEqual(orig, h.snapshot());
+});
+
+// Check that telemetry records only when it is suppose to.
+add_task(async 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(async function test_expired_histogram() {
+  var test_expired_id = "TELEMETRY_TEST_EXPIRED";
+  var dummy = Telemetry.getHistogramById(test_expired_id);
+
+  dummy.add(1);
+
+  for (let process of ["main", "content", "gpu", "extension"]) {
+    let histograms = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    );
+    if (!(process in histograms)) {
+      info("Nothing present for process " + process);
+      continue;
+    }
+    Assert.equal(histograms[process].__expired__, undefined);
+  }
+  let parentHgrams = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.equal(parentHgrams[test_expired_id], undefined);
+});
+
+add_task(async function test_keyed_expired_histogram() {
+  var test_expired_id = "TELEMETRY_TEST_EXPIRED_KEYED";
+  var dummy = Telemetry.getKeyedHistogramById(test_expired_id);
+  dummy.add("someKey", 1);
+
+  const histograms = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  );
+  for (let process of ["parent", "content", "gpu", "extension"]) {
+    if (!(process in histograms)) {
+      info("Nothing present for process " + process);
+      continue;
+    }
+    Assert.ok(
+      !(test_expired_id in histograms[process]),
+      "The expired keyed histogram must not be reported"
+    );
+  }
+});
+
+add_task(async 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(async 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 = {
+    range: [1, 2],
+    bucket_count: 3,
+    histogram_type: 2,
+    sum: 1,
+    values: { 0: 0, 1: 1, 2: 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].values = { 0: 1, 1: 0 };
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let parentHgrams = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.deepEqual(parentHgrams[KEYED_ID], testSnapShot);
+
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+});
+
+add_task(async function test_keyed_count_histogram() {
+  const KEYED_ID = "TELEMETRY_TEST_KEYED_COUNT";
+  const KEYS = numberRange(0, 5).map(i => "key" + (i + 1));
+  let histogramBase = {
+    range: [1, 2],
+    bucket_count: 3,
+    histogram_type: 4,
+    sum: 0,
+    values: { 0: 1, 1: 0 },
+  };
+  let testHistograms = numberRange(0, 5).map(i =>
+    JSON.parse(JSON.stringify(histogramBase))
+  );
+  let testKeys = [];
+  let testSnapShot = {};
+
+  let h = Telemetry.getKeyedHistogramById(KEYED_ID);
+  h.clear();
+  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].values[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].values[0] = 1;
+  testHistograms[4].sum = 1;
+  testSnapShot[key] = testHistograms[4];
+
+  Assert.deepEqual(h.keys().sort(), testKeys);
+  Assert.deepEqual(h.snapshot(), testSnapShot);
+
+  let parentHgrams = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.deepEqual(parentHgrams[KEYED_ID], testSnapShot);
+
+  // Test clearing categorical histogram.
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+
+  // Test leaving out the value argument. That should increment by 1.
+  h.add("key");
+  Assert.equal(h.snapshot().key.sum, 1);
+});
+
+add_task(async function test_keyed_categorical_histogram() {
+  const KEYED_ID = "TELEMETRY_TEST_KEYED_CATEGORICAL";
+  const KEYS = numberRange(0, 5).map(i => "key" + (i + 1));
+
+  let h = Telemetry.getKeyedHistogramById(KEYED_ID);
+
+  for (let k of KEYS) {
+    // Test adding both per label and index.
+    for (let v of ["CommonLabel", "Label2", "Label3", "Label3", 0, 0, 1]) {
+      h.add(k, v);
+    }
+
+    // The |add| method should not throw for unexpected values, but rather
+    // print an error message in the console.
+    for (let s of ["", "Label4", "1234"]) {
+      h.add(k, s);
+    }
+  }
+
+  // Check that the set of keys in the snapshot is what we expect.
+  let snapshot = h.snapshot();
+  let snapshotKeys = Object.keys(snapshot);
+  Assert.equal(KEYS.length, snapshotKeys.length);
+  Assert.ok(KEYS.every(k => snapshotKeys.includes(k)));
+
+  // Check the snapshot values.
+  for (let k of KEYS) {
+    Assert.ok(k in snapshot);
+    Assert.equal(snapshot[k].sum, 6);
+    Assert.deepEqual(snapshot[k].range, [1, 50]);
+    Assert.deepEqual(snapshot[k].values, { 0: 3, 1: 2, 2: 2, 3: 0 });
+  }
+});
+
+add_task(async 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] = {
+    range: [1, 2],
+    bucket_count: 3,
+    histogram_type: 3,
+    sum: 1,
+    values: { 0: 0, 1: 1, 2: 0 },
+  };
+
+  Assert.deepEqual(h.keys().sort(), [KEY]);
+  Assert.deepEqual(h.snapshot(), testSnapshot);
+
+  let parentHgrams = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.deepEqual(parentHgrams[KEYED_ID], testSnapshot);
+
+  h.clear();
+  Assert.deepEqual(h.keys(), []);
+  Assert.deepEqual(h.snapshot(), {});
+});
+
+add_task(async 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.ok(!(TEST_KEY in h.snapshot()));
+
+  // 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.ok(
+    !(TEST_KEY in h.snapshot()),
+    "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(async 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(async 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.ok(
+    !(TEST_KEY in h.snapshot()),
+    "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(async function test_histogramSnapshots() {
+  let keyed = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_COUNT");
+  keyed.add("a", 1);
+
+  // Check that keyed histograms are not returned
+  let parentHgrams = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.ok(!("TELEMETRY_TEST_KEYED_COUNT" in parentHgrams));
+});
+
+add_task(async function test_datasets() {
+  // Check that datasets work as expected.
+
+  const currentRecordExtended = Telemetry.canRecordExtended;
+
+  // Clear everything out
+  Telemetry.getSnapshotForHistograms("main", true /* clear */);
+  Telemetry.getSnapshotForKeyedHistograms("main", true /* clear */);
+
+  // Empty histograms are filtered. Let's record what we check below.
+  Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTIN").add(1);
+  Telemetry.getHistogramById("TELEMETRY_TEST_RELEASE_OPTOUT").add(1);
+  // Keyed flag histograms are skipped if empty, let's add data
+  Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_FLAG").add("a", 1);
+  Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTIN").add(
+    "a",
+    1
+  );
+  Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT").add(
+    "a",
+    1
+  );
+
+  // Check that registeredHistogram works properly
+  Telemetry.canRecordExtended = true;
+  let registered = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  );
+  registered = new Set(Object.keys(registered.parent));
+  Assert.ok(registered.has("TELEMETRY_TEST_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_RELEASE_OPTIN"));
+  Assert.ok(registered.has("TELEMETRY_TEST_RELEASE_OPTOUT"));
+  Telemetry.canRecordExtended = false;
+  registered = Telemetry.getSnapshotForHistograms("main", false /* clear */);
+  registered = new Set(Object.keys(registered.parent));
+  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
+  Telemetry.canRecordExtended = true;
+  registered = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  );
+  registered = new Set(Object.keys(registered.parent));
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT"));
+  Telemetry.canRecordExtended = false;
+  registered = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  );
+  registered = new Set(Object.keys(registered.parent));
+  Assert.ok(!registered.has("TELEMETRY_TEST_KEYED_FLAG"));
+  Assert.ok(registered.has("TELEMETRY_TEST_KEYED_RELEASE_OPTOUT"));
+
+  Telemetry.canRecordExtended = currentRecordExtended;
+});
+
+add_task(async function test_keyed_keys() {
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_KEYS");
+  h.clear();
+  Telemetry.clearScalars();
+
+  // The |add| method should not throw for keys that are not allowed.
+  h.add("testkey", true);
+  h.add("thirdKey", false);
+  h.add("not-allowed", true);
+
+  // Check that we have the expected keys.
+  let snap = h.snapshot();
+  Assert.equal(Object.keys(snap).length, 2, "Only 2 keys must be recorded.");
+  Assert.ok("testkey" in snap, "'testkey' must be recorded.");
+  Assert.ok("thirdKey" in snap, "'thirdKey' must be recorded.");
+  Assert.deepEqual(
+    snap.testkey.values,
+    { 0: 0, 1: 1, 2: 0 },
+    "'testkey' must contain the correct value."
+  );
+  Assert.deepEqual(
+    snap.thirdKey.values,
+    { 0: 1, 1: 0 },
+    "'thirdKey' must contain the correct value."
+  );
+
+  // Keys that are not allowed must not be recorded.
+  Assert.ok(!("not-allowed" in snap), "'not-allowed' must not be recorded.");
+
+  // Check that these failures were correctly tracked.
+  const parentScalars = Telemetry.getSnapshotForKeyedScalars(
+    "main",
+    false
+  ).parent;
+  const scalarName = "telemetry.accumulate_unknown_histogram_keys";
+  Assert.ok(
+    scalarName in parentScalars,
+    "Accumulation to unallowed keys must be reported."
+  );
+  Assert.ok(
+    "TELEMETRY_TEST_KEYED_KEYS" in parentScalars[scalarName],
+    "Accumulation to unallowed keys must be recorded with the correct key."
+  );
+  Assert.equal(
+    parentScalars[scalarName].TELEMETRY_TEST_KEYED_KEYS,
+    1,
+    "Accumulation to unallowed keys must report the correct value."
+  );
+});
+
+add_task(async function test_count_multiple_samples() {
+  let valid = [1, 1, 3, 0];
+  let invalid = ["1", "0", "", "random"];
+
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_COUNT");
+  h.clear();
+
+  // If the array contains even a single invalid value, no accumulation should take place
+  // Keep the valid values in front of invalid to check if it is simply accumulating as
+  // it's traversing the array and throwing upon first invalid value. That should not happen.
+  h.add(valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.equal(s1.sum, 0);
+  // Ensure that no accumulations of 0-like values took place.
+  // These accumulations won't increase the sum.
+  Assert.deepEqual({}, s1.values);
+
+  h.add(valid);
+  let s2 = h.snapshot();
+  Assert.deepEqual(s2.values, { 0: 4, 1: 0 });
+  Assert.equal(s2.sum, 5);
+});
+
+add_task(async function test_categorical_multiple_samples() {
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_CATEGORICAL");
+  h.clear();
+  let valid = ["CommonLabel", "Label2", "Label3", "Label3", 0, 0, 1];
+  let invalid = ["", "Label4", "1234", "0", "1", 5000];
+
+  // At least one invalid parameter, so no accumulation should happen here
+  // Valid values in front of invalid.
+  h.add(valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.equal(s1.sum, 0);
+  Assert.deepEqual({}, s1.values);
+
+  h.add(valid);
+  let snapshot = h.snapshot();
+  Assert.equal(snapshot.sum, 6);
+  Assert.deepEqual(snapshot.values, { 0: 3, 1: 2, 2: 2, 3: 0 });
+});
+
+add_task(async function test_boolean_multiple_samples() {
+  let valid = [true, false, 0, 1, 2];
+  let invalid = ["", "0", "1", ",2", "true", "false", "random"];
+
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_BOOLEAN");
+  h.clear();
+
+  // At least one invalid parameter, so no accumulation should happen here
+  // Valid values in front of invalid.
+  h.add(valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.equal(s1.sum, 0);
+  Assert.deepEqual({}, s1.values);
+
+  h.add(valid);
+  let s = h.snapshot();
+  Assert.deepEqual(s.values, { 0: 2, 1: 3, 2: 0 });
+  Assert.equal(s.sum, 3);
+});
+
+add_task(async function test_linear_multiple_samples() {
+  // According to telemetry.mozilla.org/histogram-simulator, bucket at
+  // index 1 of TELEMETRY_TEST_LINEAR has max value of 268.44M
+  let valid = [0, 1, 5, 10, 268450000, 268450001, Math.pow(2, 31) + 1];
+  let invalid = ["", "0", "1", "random"];
+
+  let h = Telemetry.getHistogramById("TELEMETRY_TEST_LINEAR");
+  h.clear();
+
+  // At least one invalid paramater, so no accumulations.
+  // Valid values in front of invalid.
+  h.add(valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.equal(s1.sum, 0);
+  Assert.deepEqual({}, s1.values);
+
+  h.add(valid);
+  let s2 = h.snapshot();
+  // Values >= INT32_MAX are accumulated as INT32_MAX - 1
+  Assert.equal(s2.sum, valid.reduce((acc, cur) => acc + cur) - 3);
+  Assert.deepEqual(Object.values(s2.values), [1, 3, 2, 1]);
+});
+
+add_task(async function test_keyed_no_arguments() {
+  // Test for no accumulation when add is called with no arguments
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_LINEAR");
+  h.clear();
+
+  h.add();
+
+  // No keys should be added due to no accumulation.
+  Assert.equal(h.keys().length, 0);
+});
+
+add_task(async function test_keyed_categorical_invalid_string() {
+  // Test for no accumulation when add is called on a
+  // keyed categorical histogram with an invalid string label.
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_CATEGORICAL");
+  h.clear();
+
+  h.add("someKey", "#notALabel");
+
+  // No keys should be added due to no accumulation.
+  Assert.equal(h.keys().length, 0);
+});
+
+add_task(async function test_keyed_count_multiple_samples() {
+  let valid = [1, 1, 3, 0];
+  let invalid = ["1", "0", "", "random"];
+  let key = "somekeystring";
+
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_COUNT");
+  h.clear();
+
+  // If the array contains even a single invalid value, no accumulation should take place
+  // Keep the valid values in front of invalid to check if it is simply accumulating as
+  // it's traversing the array and throwing upon first invalid value. That should not happen.
+  h.add(key, valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.ok(!(key in s1));
+
+  h.add(key, valid);
+  let s2 = h.snapshot()[key];
+  Assert.deepEqual(s2.values, { 0: 4, 1: 0 });
+  Assert.equal(s2.sum, 5);
+});
+
+add_task(async function test_keyed_categorical_multiple_samples() {
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_CATEGORICAL");
+  h.clear();
+  let valid = ["CommonLabel", "Label2", "Label3", "Label3", 0, 0, 1];
+  let invalid = ["", "Label4", "1234", "0", "1", 5000];
+  let key = "somekeystring";
+
+  // At least one invalid parameter, so no accumulation should happen here
+  // Valid values in front of invalid.
+  h.add(key, valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.ok(!(key in s1));
+
+  h.add(key, valid);
+  let snapshot = h.snapshot()[key];
+  Assert.equal(snapshot.sum, 6);
+  Assert.deepEqual(Object.values(snapshot.values), [3, 2, 2, 0]);
+});
+
+add_task(async function test_keyed_boolean_multiple_samples() {
+  let valid = [true, false, 0, 1, 2];
+  let invalid = ["", "0", "1", ",2", "true", "false", "random"];
+  let key = "somekey";
+
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_BOOLEAN");
+  h.clear();
+
+  // At least one invalid parameter, so no accumulation should happen here
+  // Valid values in front of invalid.
+  h.add(key, valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.ok(!(key in s1));
+
+  h.add(key, valid);
+  let s = h.snapshot()[key];
+  Assert.deepEqual(s.values, { 0: 2, 1: 3, 2: 0 });
+  Assert.equal(s.sum, 3);
+});
+
+add_task(async function test_keyed_linear_multiple_samples() {
+  // According to telemetry.mozilla.org/histogram-simulator, bucket at
+  // index 1 of TELEMETRY_TEST_LINEAR has max value of 3.13K
+  let valid = [0, 1, 5, 10, 268450000, 268450001, Math.pow(2, 31) + 1];
+  let invalid = ["", "0", "1", "random"];
+  let key = "somestring";
+
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_LINEAR");
+  h.clear();
+
+  // At least one invalid paramater, so no accumulations.
+  // Valid values in front of invalid.
+  h.add(key, valid.concat(invalid));
+  let s1 = h.snapshot();
+  Assert.ok(!(key in s1));
+
+  h.add(key, valid);
+  let s2 = h.snapshot()[key];
+  // Values >= INT32_MAX are accumulated as INT32_MAX - 1
+  Assert.equal(s2.sum, valid.reduce((acc, cur) => acc + cur) - 3);
+  Assert.deepEqual(s2.range, [1, 250000]);
+  Assert.deepEqual(s2.values, { 0: 1, 1: 3, 250000: 3 });
+});
+
+add_task(async function test_non_array_non_string_obj() {
+  let invalid_obj = {
+    prop1: "someValue",
+    prop2: "someOtherValue",
+  };
+  let key = "someString";
+
+  let h = Telemetry.getKeyedHistogramById("TELEMETRY_TEST_KEYED_LINEAR");
+  h.clear();
+
+  h.add(key, invalid_obj);
+  Assert.equal(h.keys().length, 0);
+});
+
+add_task(
+  {
+    skip_if: () => gIsAndroid,
+  },
+  async function test_productSpecificHistograms() {
+    const DEFAULT_PRODUCTS_HISTOGRAM = "TELEMETRY_TEST_DEFAULT_PRODUCTS";
+    const DESKTOP_ONLY_HISTOGRAM = "TELEMETRY_TEST_DESKTOP_ONLY";
+    const MULTIPRODUCT_HISTOGRAM = "TELEMETRY_TEST_MULTIPRODUCT";
+    const MOBILE_ONLY_HISTOGRAM = "TELEMETRY_TEST_MOBILE_ONLY";
+
+    var default_histo = Telemetry.getHistogramById(DEFAULT_PRODUCTS_HISTOGRAM);
+    var desktop_histo = Telemetry.getHistogramById(DESKTOP_ONLY_HISTOGRAM);
+    var multiproduct_histo = Telemetry.getHistogramById(MULTIPRODUCT_HISTOGRAM);
+    var mobile_histo = Telemetry.getHistogramById(MOBILE_ONLY_HISTOGRAM);
+    default_histo.clear();
+    desktop_histo.clear();
+    multiproduct_histo.clear();
+    mobile_histo.clear();
+
+    default_histo.add(42);
+    desktop_histo.add(42);
+    multiproduct_histo.add(42);
+    mobile_histo.add(42);
+
+    let histograms = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+
+    Assert.ok(
+      DEFAULT_PRODUCTS_HISTOGRAM in histograms,
+      "Should have recorded default products histogram"
+    );
+    Assert.ok(
+      DESKTOP_ONLY_HISTOGRAM in histograms,
+      "Should have recorded desktop-only histogram"
+    );
+    Assert.ok(
+      MULTIPRODUCT_HISTOGRAM in histograms,
+      "Should have recorded multiproduct histogram"
+    );
+
+    Assert.ok(
+      !(MOBILE_ONLY_HISTOGRAM in histograms),
+      "Should not have recorded mobile-only histogram"
+    );
+  }
+);
+
+add_task(
+  {
+    skip_if: () => !gIsAndroid,
+  },
+  async function test_mobileSpecificHistograms() {
+    const DEFAULT_PRODUCTS_HISTOGRAM = "TELEMETRY_TEST_DEFAULT_PRODUCTS";
+    const DESKTOP_ONLY_HISTOGRAM = "TELEMETRY_TEST_DESKTOP_ONLY";
+    const MULTIPRODUCT_HISTOGRAM = "TELEMETRY_TEST_MULTIPRODUCT";
+    const MOBILE_ONLY_HISTOGRAM = "TELEMETRY_TEST_MOBILE_ONLY";
+
+    var default_histo = Telemetry.getHistogramById(DEFAULT_PRODUCTS_HISTOGRAM);
+    var desktop_histo = Telemetry.getHistogramById(DESKTOP_ONLY_HISTOGRAM);
+    var multiproduct_histo = Telemetry.getHistogramById(MULTIPRODUCT_HISTOGRAM);
+    var mobile_histo = Telemetry.getHistogramById(MOBILE_ONLY_HISTOGRAM);
+    default_histo.clear();
+    desktop_histo.clear();
+    multiproduct_histo.clear();
+    mobile_histo.clear();
+
+    default_histo.add(1);
+    desktop_histo.add(1);
+    multiproduct_histo.add(1);
+    mobile_histo.add(1);
+
+    let histograms = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+
+    Assert.ok(
+      DEFAULT_PRODUCTS_HISTOGRAM in histograms,
+      "Should have recorded default products histogram"
+    );
+    Assert.ok(
+      MOBILE_ONLY_HISTOGRAM in histograms,
+      "Should have recorded mobile-only histogram"
+    );
+    Assert.ok(
+      MULTIPRODUCT_HISTOGRAM in histograms,
+      "Should have recorded multiproduct histogram"
+    );
+
+    Assert.ok(
+      !(DESKTOP_ONLY_HISTOGRAM in histograms),
+      "Should not have recorded desktop-only histogram"
+    );
+  }
+);
+
+add_task(async function test_productsOverride() {
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+  const DEFAULT_PRODUCTS_HISTOGRAM = "TELEMETRY_TEST_DEFAULT_PRODUCTS";
+  const DESKTOP_ONLY_HISTOGRAM = "TELEMETRY_TEST_DESKTOP_ONLY";
+  const MULTIPRODUCT_HISTOGRAM = "TELEMETRY_TEST_MULTIPRODUCT";
+  const MOBILE_ONLY_HISTOGRAM = "TELEMETRY_TEST_MOBILE_ONLY";
+
+  var default_histo = Telemetry.getHistogramById(DEFAULT_PRODUCTS_HISTOGRAM);
+  var desktop_histo = Telemetry.getHistogramById(DESKTOP_ONLY_HISTOGRAM);
+  var multiproduct_histo = Telemetry.getHistogramById(MULTIPRODUCT_HISTOGRAM);
+  var mobile_histo = Telemetry.getHistogramById(MOBILE_ONLY_HISTOGRAM);
+  default_histo.clear();
+  desktop_histo.clear();
+  multiproduct_histo.clear();
+  mobile_histo.clear();
+
+  default_histo.add(1);
+  desktop_histo.add(1);
+  multiproduct_histo.add(1);
+  mobile_histo.add(1);
+
+  let histograms = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+
+  Assert.ok(
+    DEFAULT_PRODUCTS_HISTOGRAM in histograms,
+    "Should have recorded default products histogram"
+  );
+  Assert.ok(
+    MOBILE_ONLY_HISTOGRAM in histograms,
+    "Should have recorded mobile-only histogram"
+  );
+  Assert.ok(
+    MULTIPRODUCT_HISTOGRAM in histograms,
+    "Should have recorded multiproduct histogram"
+  );
+
+  Assert.ok(
+    DESKTOP_ONLY_HISTOGRAM in histograms,
+    "Should not have recorded desktop-only histogram"
+  );
+  Services.prefs.clearUserPref(
+    "toolkit.telemetry.testing.overrideProductsCheck"
+  );
+});
+
+add_task(
+  {
+    skip_if: () => gIsAndroid,
+  },
+  async function test_clearHistogramsOnSnapshot() {
+    const COUNT = "TELEMETRY_TEST_COUNT";
+    let h = Telemetry.getHistogramById(COUNT);
+    h.clear();
+    let snapshot;
+
+    // The first snapshot should be empty, nothing recorded.
+    snapshot = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+    Assert.ok(!(COUNT in snapshot));
+
+    // After recording into a histogram, the data should be in the snapshot. Don't delete it.
+    h.add(1);
+
+    Assert.equal(h.snapshot().sum, 1);
+    snapshot = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+    Assert.ok(COUNT in snapshot);
+    Assert.equal(snapshot[COUNT].sum, 1);
+
+    // After recording into a histogram again, the data should be updated and in the snapshot.
+    // Clean up after.
+    h.add(41);
+
+    Assert.equal(h.snapshot().sum, 42);
+    snapshot = Telemetry.getSnapshotForHistograms(
+      "main",
+      true /* clear */
+    ).parent;
+    Assert.ok(COUNT in snapshot);
+    Assert.equal(snapshot[COUNT].sum, 42);
+
+    // Finally, no data should be in the snapshot.
+    Assert.equal(h.snapshot().sum, 0);
+    snapshot = Telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+    Assert.ok(!(COUNT in snapshot));
+  }
+);
+
+add_task(async function test_valid_os_smoketest() {
+  let nonExistingProbe;
+  let existingProbe;
+
+  switch (AppConstants.platform) {
+    case "linux":
+      nonExistingProbe = "TELEMETRY_TEST_OS_ANDROID_ONLY";
+      existingProbe = "TELEMETRY_TEST_OS_LINUX_ONLY";
+      break;
+    case "macosx":
+      nonExistingProbe = "TELEMETRY_TEST_OS_ANDROID_ONLY";
+      existingProbe = "TELEMETRY_TEST_OS_MAC_ONLY";
+      break;
+    case "win":
+      nonExistingProbe = "TELEMETRY_TEST_OS_ANDROID_ONLY";
+      existingProbe = "TELEMETRY_TEST_OS_WIN_ONLY";
+      break;
+    case "android":
+      nonExistingProbe = "TELEMETRY_TEST_OS_LINUX_ONLY";
+      existingProbe = "TELEMETRY_TEST_OS_ANDROID_ONLY";
+      break;
+    default:
+      /* Unknown OS. Let's not test OS-specific probes */
+      return;
+  }
+
+  Assert.throws(
+    () => Telemetry.getHistogramById(nonExistingProbe),
+    /NS_ERROR_FAILURE/,
+    `Should throw on ${nonExistingProbe} probe that's not available on ${AppConstants.platform}`
+  );
+
+  let h = Telemetry.getHistogramById(existingProbe);
+  h.clear();
+  h.add(1);
+  let snapshot = Telemetry.getSnapshotForHistograms(
+    "main",
+    false /* clear */
+  ).parent;
+  Assert.ok(
+    existingProbe in snapshot,
+    `${existingProbe} should be recorded on ${AppConstants.platform}`
+  );
+  Assert.equal(snapshot[existingProbe].sum, 1);
+});
+
+add_task(async function test_multistore_individual_histogram() {
+  Telemetry.canRecordExtended = true;
+
+  let id;
+  let hist;
+  let snapshot;
+
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  snapshot = hist.snapshot();
+  Assert.equal(0, snapshot.sum, `Histogram ${id} should be empty.`);
+  hist.add(1);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    1,
+    snapshot.sum,
+    `Histogram ${id} should have recorded one value.`
+  );
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.equal(0, snapshot.sum, `Histogram ${id} should be cleared.`);
+
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  hist = Telemetry.getHistogramById(id);
+  snapshot = hist.snapshot();
+  Assert.equal(0, snapshot.sum, `Histogram ${id} should be empty.`);
+  hist.add(1);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    1,
+    snapshot.sum,
+    `Histogram ${id} should have recorded one value.`
+  );
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.equal(0, snapshot.sum, `Histogram ${id} should be cleared.`);
+
+  // When sync only, then the snapshot will be empty on the main store
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+  hist.add(1);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  hist = Telemetry.getKeyedHistogramById(id);
+  snapshot = hist.snapshot();
+  Assert.deepEqual({}, snapshot, `Histogram ${id} should be empty.`);
+  hist.add("key-a", 1);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    1,
+    snapshot["key-a"].sum,
+    `Histogram ${id} should have recorded one value.`
+  );
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.deepEqual({}, snapshot, `Histogram ${id} should be cleared.`);
+
+  // When sync only, then the snapshot will be empty on the main store
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  hist = Telemetry.getKeyedHistogramById(id);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+  hist.add("key-a", 1);
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.equal(
+    undefined,
+    snapshot,
+    `Histogram ${id} should not be in the 'main' storage`
+  );
+});
+
+add_task(async function test_multistore_main_snapshot() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForHistograms("main", true);
+  Telemetry.getSnapshotForKeyedHistograms("main", true);
+
+  let id;
+  let hist;
+  let snapshot;
+
+  // Plain histograms
+
+  // Fill with data
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  // Getting snapshot and NOT clearing (using default values for optional parameters)
+  snapshot = Telemetry.getSnapshotForHistograms().parent;
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  // Data should still be in, getting snapshot and clearing
+  snapshot = Telemetry.getSnapshotForHistograms(
+    "main",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  // Should be empty after clearing
+  snapshot = Telemetry.getSnapshotForHistograms(
+    "main",
+    /* clear */ false
+  ).parent;
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  // Keyed histograms
+
+  // Fill with data
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-a", 1);
+
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-b", 1);
+
+  // Getting snapshot and NOT clearing (using default values for optional parameters)
+  snapshot = Telemetry.getSnapshotForKeyedHistograms().parent;
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  // Data should still be in, getting snapshot and clearing
+  snapshot = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  // Should be empty after clearing
+  snapshot = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    /* clear */ false
+  ).parent;
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+});
+
+add_task(async function test_multistore_argument_handling() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForHistograms("main", true);
+  Telemetry.getSnapshotForHistograms("sync", true);
+  Telemetry.getSnapshotForKeyedHistograms("main", true);
+  Telemetry.getSnapshotForKeyedHistograms("sync", true);
+
+  let id;
+  let hist;
+  let snapshot;
+
+  // Plain Histograms
+
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(37);
+
+  // No argument
+  snapshot = hist.snapshot();
+  Assert.equal(37, snapshot.sum, `${id} should be in a default store snapshot`);
+
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.equal(0, snapshot.sum, `${id} should be cleared in the default store`);
+
+  snapshot = hist.snapshot({ store: "sync" });
+  Assert.equal(
+    37,
+    snapshot.sum,
+    `${id} should not have been cleared in the sync store`
+  );
+
+  Assert.throws(
+    () => hist.snapshot(2, "or", "more", "arguments"),
+    /one argument/,
+    "snapshot should check argument count"
+  );
+  Assert.throws(
+    () => hist.snapshot(2),
+    /object argument/,
+    "snapshot should check argument type"
+  );
+  Assert.throws(
+    () => hist.snapshot({}),
+    /property/,
+    "snapshot should check for object property"
+  );
+  Assert.throws(
+    () => hist.snapshot({ store: 1 }),
+    /string/,
+    "snapshot should check object property's type"
+  );
+
+  Assert.throws(
+    () => hist.clear(2, "or", "more", "arguments"),
+    /one argument/,
+    "clear should check argument count"
+  );
+  Assert.throws(
+    () => hist.clear(2),
+    /object argument/,
+    "clear should check argument type"
+  );
+  Assert.throws(
+    () => hist.clear({}),
+    /property/,
+    "clear should check for object property"
+  );
+  Assert.throws(
+    () => hist.clear({ store: 1 }),
+    /string/,
+    "clear should check object property's type"
+  );
+
+  // Keyed Histogram
+
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-1", 37);
+
+  // No argument
+  snapshot = hist.snapshot();
+  Assert.equal(
+    37,
+    snapshot["key-1"].sum,
+    `${id} should be in a default store snapshot`
+  );
+
+  hist.clear();
+  snapshot = hist.snapshot();
+  Assert.ok(
+    !("key-1" in snapshot),
+    `${id} should be cleared in the default store`
+  );
+
+  snapshot = hist.snapshot({ store: "sync" });
+  Assert.equal(
+    37,
+    snapshot["key-1"].sum,
+    `${id} should not have been cleared in the sync store`
+  );
+
+  Assert.throws(
+    () => hist.snapshot(2, "or", "more", "arguments"),
+    /one argument/,
+    "snapshot should check argument count"
+  );
+  Assert.throws(
+    () => hist.snapshot(2),
+    /object argument/,
+    "snapshot should check argument type"
+  );
+  Assert.throws(
+    () => hist.snapshot({}),
+    /property/,
+    "snapshot should check for object property"
+  );
+  Assert.throws(
+    () => hist.snapshot({ store: 1 }),
+    /string/,
+    "snapshot should check object property's type"
+  );
+
+  Assert.throws(
+    () => hist.clear(2, "or", "more", "arguments"),
+    /one argument/,
+    "clear should check argument count"
+  );
+  Assert.throws(
+    () => hist.clear(2),
+    /object argument/,
+    "clear should check argument type"
+  );
+  Assert.throws(
+    () => hist.clear({}),
+    /property/,
+    "clear should check for object property"
+  );
+  Assert.throws(
+    () => hist.clear({ store: 1 }),
+    /string/,
+    "clear should check object property's type"
+  );
+});
+
+add_task(async function test_multistore_sync_snapshot() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForHistograms("main", true);
+  Telemetry.getSnapshotForHistograms("sync", true);
+
+  let id;
+  let hist;
+  let snapshot;
+
+  // Plain histograms
+
+  // Fill with data
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  hist = Telemetry.getHistogramById(id);
+  hist.add(1);
+
+  // Getting snapshot and clearing
+  snapshot = Telemetry.getSnapshotForHistograms(
+    "main",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  snapshot = Telemetry.getSnapshotForHistograms(
+    "sync",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a sync store snapshot`);
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a sync store snapshot`);
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  Assert.ok(id in snapshot, `${id} should be in a sync store snapshot`);
+});
+
+add_task(async function test_multistore_keyed_sync_snapshot() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForKeyedHistograms("main", true);
+  Telemetry.getSnapshotForKeyedHistograms("sync", true);
+
+  let id;
+  let hist;
+  let snapshot;
+
+  // Plain histograms
+
+  // Fill with data
+  id = "TELEMETRY_TEST_KEYED_LINEAR";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-1", 1);
+
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-1", 1);
+
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  hist = Telemetry.getKeyedHistogramById(id);
+  hist.add("key-1", 1);
+
+  // Getting snapshot and clearing
+  snapshot = Telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_KEYED_LINEAR";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a main store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  Assert.ok(!(id in snapshot), `${id} should not be in a main store snapshot`);
+
+  snapshot = Telemetry.getSnapshotForKeyedHistograms(
+    "sync",
+    /* clear */ true
+  ).parent;
+  id = "TELEMETRY_TEST_KEYED_LINEAR";
+  Assert.ok(!(id in snapshot), `${id} should not be in a sync store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  Assert.ok(id in snapshot, `${id} should be in a sync store snapshot`);
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  Assert.ok(id in snapshot, `${id} should be in a sync store snapshot`);
+});
+
+add_task(async function test_multistore_plain_individual_snapshot() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForHistograms("main", true);
+  Telemetry.getSnapshotForHistograms("sync", true);
+
+  let id;
+  let hist;
+
+  id = "TELEMETRY_TEST_MAIN_ONLY";
+  hist = Telemetry.getHistogramById(id);
+
+  hist.add(37);
+  Assert.deepEqual(37, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "sync" }));
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual(0, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "sync" }));
+
+  id = "TELEMETRY_TEST_MULTIPLE_STORES";
+  hist = Telemetry.getHistogramById(id);
+
+  hist.add(37);
+  Assert.deepEqual(37, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" }).sum);
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual(0, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" }).sum);
+
+  hist.add(3);
+  Assert.deepEqual(3, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(40, hist.snapshot({ store: "sync" }).sum);
+
+  hist.clear({ store: "sync" });
+  Assert.deepEqual(3, hist.snapshot({ store: "main" }).sum);
+  Assert.deepEqual(0, hist.snapshot({ store: "sync" }).sum);
+
+  id = "TELEMETRY_TEST_SYNC_ONLY";
+  hist = Telemetry.getHistogramById(id);
+
+  hist.add(37);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" }).sum);
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" }).sum);
+
+  hist.add(3);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(40, hist.snapshot({ store: "sync" }).sum);
+
+  hist.clear({ store: "sync" });
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(0, hist.snapshot({ store: "sync" }).sum);
+});
+
+add_task(async function test_multistore_keyed_individual_snapshot() {
+  Telemetry.canRecordExtended = true;
+  // Clear histograms
+  Telemetry.getSnapshotForKeyedHistograms("main", true);
+  Telemetry.getSnapshotForKeyedHistograms("sync", true);
+
+  let id;
+  let hist;
+
+  id = "TELEMETRY_TEST_KEYED_LINEAR";
+  hist = Telemetry.getKeyedHistogramById(id);
+
+  hist.add("key-1", 37);
+  Assert.deepEqual(37, hist.snapshot({ store: "main" })["key-1"].sum);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "sync" }));
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual({}, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(undefined, hist.snapshot({ store: "sync" }));
+
+  hist.add("key-1", 4);
+  hist.clear({ store: "sync" });
+  Assert.deepEqual(4, hist.snapshot({ store: "main" })["key-1"].sum);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "sync" }));
+
+  id = "TELEMETRY_TEST_KEYED_MULTIPLE_STORES";
+  hist = Telemetry.getKeyedHistogramById(id);
+
+  hist.add("key-1", 37);
+  Assert.deepEqual(37, hist.snapshot({ store: "main" })["key-1"].sum);
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual({}, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.add("key-1", 3);
+  Assert.deepEqual(3, hist.snapshot({ store: "main" })["key-1"].sum);
+  Assert.deepEqual(40, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.clear({ store: "sync" });
+  Assert.deepEqual(3, hist.snapshot({ store: "main" })["key-1"].sum);
+  Assert.deepEqual({}, hist.snapshot({ store: "sync" }));
+
+  id = "TELEMETRY_TEST_KEYED_SYNC_ONLY";
+  hist = Telemetry.getKeyedHistogramById(id);
+
+  hist.add("key-1", 37);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.clear({ store: "main" });
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(37, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.add("key-1", 3);
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual(40, hist.snapshot({ store: "sync" })["key-1"].sum);
+
+  hist.clear({ store: "sync" });
+  Assert.deepEqual(undefined, hist.snapshot({ store: "main" }));
+  Assert.deepEqual({}, hist.snapshot({ store: "sync" }));
+});
+
+add_task(async function test_can_record_in_process_regression_bug_1530361() {
+  Telemetry.getSnapshotForHistograms("main", true);
+
+  // The socket and gpu processes should not have any histograms.
+  // Flag and count histograms have defaults, so if we're accidentally recording them
+  // in these processes they'd show up even immediately after being cleared.
+  let snapshot = Telemetry.getSnapshotForHistograms("main", true);
+
+  Assert.deepEqual(
+    snapshot.gpu,
+    {},
+    "No histograms should have been recorded for the gpu process"
+  );
+  Assert.deepEqual(
+    snapshot.socket,
+    {},
+    "No histograms should have been recorded for the socket process"
+  );
+});
+
+add_task(function test_knows_its_name() {
+  let h;
+
+  // Plain histograms
+  const histNames = [
+    "TELEMETRY_TEST_FLAG",
+    "TELEMETRY_TEST_COUNT",
+    "TELEMETRY_TEST_CATEGORICAL",
+    "TELEMETRY_TEST_EXPIRED",
+  ];
+
+  for (let name of histNames) {
+    h = Telemetry.getHistogramById(name);
+    Assert.equal(name, h.name());
+  }
+
+  // Keyed histograms
+  const keyedHistNames = [
+    "TELEMETRY_TEST_KEYED_EXPONENTIAL",
+    "TELEMETRY_TEST_KEYED_BOOLEAN",
+    "TELEMETRY_TEST_EXPIRED_KEYED",
+  ];
+
+  for (let name of keyedHistNames) {
+    h = Telemetry.getKeyedHistogramById(name);
+    Assert.equal(name, h.name());
+  }
+});