Bug 1887765 - BackupService total backup size metric r=backup-reviewers,mconley

Differential Revision: https://phabricator.services.mozilla.com/D214438

browser/components/backup/tests/xpcshell/test_BackupService.js

@@ -17,6 +17,9 @@ const { ClientID } = ChromeUtils.importESModule(
 );
 
 add_setup(function () {
+  // FOG needs to be initialized in order for data to flow.
+  Services.fog.initializeFOG();
+
   // Much of this setup is copied from toolkit/profile/xpcshell/head.js. It is
   // needed in order to put the xpcshell test environment into the state where
   // it thinks its profile is the one pointed at by
@@ -80,6 +83,11 @@ add_setup(function () {
  * @returns {Promise<undefined>}
  */
 async function testCreateBackupHelper(sandbox, taskFn) {
+  Services.fog.testResetFOG();
+  // Handle for the metric for total byte size of staging folder
+  let totalBackupSizeHistogram = TelemetryTestUtils.getAndClearHistogram(
+    "BROWSER_BACKUP_TOTAL_BACKUP_SIZE"
+  );
   const EXPECTED_CLIENT_ID = await ClientID.getClientID();
 
   let fake1ManifestEntry = { fake1: "hello from 1" };
@@ -222,6 +230,28 @@ async function testCreateBackupHelper(sandbox, taskFn) {
     "The client ID was stored properly."
   );
 
+  // 1 mebibyte minimum recorded value if staging folder is under 1 mebibyte
+  // This assumes that these BackupService tests do not create sizable fake files
+  const SMALLEST_BACKUP_SIZE_BYTES = 1048576;
+  const SMALLEST_BACKUP_SIZE_MEBIBYTES = 1;
+
+  let totalBackupSize = Glean.browserBackup.totalBackupSize.testGetValue();
+  Assert.equal(
+    totalBackupSize.count,
+    1,
+    "Should have collected a single measurement for the total backup size"
+  );
+  Assert.equal(
+    totalBackupSize.sum,
+    SMALLEST_BACKUP_SIZE_BYTES,
+    "Should have collected the right value for the total backup size"
+  );
+  TelemetryTestUtils.assertHistogram(
+    totalBackupSizeHistogram,
+    SMALLEST_BACKUP_SIZE_MEBIBYTES,
+    1
+  );
+
   taskFn(manifest);
 
   // After createBackup is more fleshed out, we're going to want to make sure

browser/components/backup/tests/xpcshell/test_MeasurementUtils_fuzzByteSize.js

@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { MeasurementUtils } = ChromeUtils.importESModule(
+  "resource:///modules/backup/MeasurementUtils.sys.mjs"
+);
+
+add_task(async function test_minimumFallback() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(250, 1000);
+  Assert.equal(
+    fuzzed,
+    1000,
+    "Should fall back to the `nearest` value when `bytes` are below `nearest`"
+  );
+});
+
+add_task(async function test_roundUp() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1500, 1000);
+  Assert.equal(
+    fuzzed,
+    2000,
+    "Should round up to 2000 when `bytes` is 1500 since that is the nearest 1000 bytes"
+  );
+});
+
+add_task(async function test_roundDown() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1499, 1000);
+  Assert.equal(
+    fuzzed,
+    1000,
+    "Should round down to 1000 when `bytes` is 1499 since that is the nearest 1000 bytes"
+  );
+});
+
+add_task(async function test_roundDownSmallerUnit() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1025, 10);
+  Assert.equal(
+    fuzzed,
+    1030,
+    "Should round 1025 up to 1030 since that is the nearest 10 bytes"
+  );
+});
+
+add_task(async function test_roundDownSmallerUnit() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1024, 10);
+  Assert.equal(
+    fuzzed,
+    1020,
+    "Should round 1024 down to 1020 since that is the nearest 10 bytes"
+  );
+});
+
+add_task(async function test_roundUpBinary() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1500, 1024);
+  Assert.equal(
+    fuzzed,
+    1024,
+    "Should round 1500 down to 1024 nearest kibibyte value"
+  );
+});
+
+add_task(async function test_roundDownBinary() {
+  const fuzzed = MeasurementUtils.fuzzByteSize(1800, 1024);
+  Assert.equal(
+    fuzzed,
+    2048,
+    "Should round 1800 up to 2048 since that is the nearest kibibyte value"
+  );
+});

browser/components/backup/tests/xpcshell/xpcshell.toml

@@ -35,6 +35,8 @@ skip-if = ["apple_silicon && automation"] # bug 1729538
 
 ["test_BackupService_takeMeasurements.js"]
 
+["test_MeasurementUtils_fuzzByteSize.js"]
+
 ["test_CookiesBackupResource.js"]
 
 ["test_CredentialsAndSecurityBackupResource.js"]