1 files changed, 97 insertions, 0 deletions
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js b/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js
new file mode 100644
index 0000000000..2231197eed
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js
@@ -0,0 +1,97 @@
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const TEST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "https://example.com"
+);
+const TEST_PAGE_NORMAL = TEST_PATH + "empty.html";
+const TEST_PAGE_FINGERPRINTER = TEST_PATH + "font-fingerprinter.html";
+
+const TELEMETRY_FONT_FINGERPRINTING_PER_TAB = "FONT_FINGERPRINTING_PER_TAB";
+
+async function clearTelemetry() {
+  Services.telemetry.getSnapshotForHistograms("main", true /* clear */);
+  Services.telemetry
+    .getHistogramById(TELEMETRY_FONT_FINGERPRINTING_PER_TAB)
+    .clear();
+}
+
+async function getHistogram(histogram_id, bucket, checkCntFn) {
+  let histogram;
+
+  // Wait until the telemetry probe appears.
+  await TestUtils.waitForCondition(() => {
+    let histograms = Services.telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    ).parent;
+
+    histogram = histograms[histogram_id];
+
+    let checkRes = false;
+
+    if (histogram) {
+      checkRes = checkCntFn ? checkCntFn(histogram.values[bucket]) : true;
+    }
+
+    return checkRes;
+  });
+
+  return histogram.values[bucket] || 0;
+}
+
+async function checkHistogram(histogram_id, bucket, expectedCnt) {
+  let cnt = await getHistogram(histogram_id, bucket, cnt => {
+    if (cnt === undefined) {
+      cnt = 0;
+    }
+
+    return cnt == expectedCnt;
+  });
+
+  is(cnt, expectedCnt, "There should be expected count in telemetry.");
+}
+
+add_setup(async function () {
+  await clearTelemetry();
+});
+
+add_task(async function test_canvas_fingerprinting_telemetry() {
+  let promiseWindowDestroyed = BrowserUtils.promiseObserved(
+    "window-global-destroyed"
+  );
+
+  // First, we open a page without any canvas fingerprinters
+  await BrowserTestUtils.withNewTab(TEST_PAGE_NORMAL, async _ => {});
+
+  // Make sure the tab was closed properly before checking Telemetry.
+  await promiseWindowDestroyed;
+
+  // Check that the telemetry has been record properly for normal page. The
+  // telemetry should show there was no known fingerprinting attempt.
+  await checkHistogram(TELEMETRY_FONT_FINGERPRINTING_PER_TAB, 0 /* false */, 1);
+
+  await clearTelemetry();
+});
+
+add_task(async function test_canvas_fingerprinting_telemetry() {
+  let promiseWindowDestroyed = BrowserUtils.promiseObserved(
+    "window-global-destroyed"
+  );
+
+  // Now open a page with a canvas fingerprinter
+  await BrowserTestUtils.withNewTab(TEST_PAGE_FINGERPRINTER, async _ => {});
+
+  // Make sure the tab was closed properly before checking Telemetry.
+  await promiseWindowDestroyed;
+
+  // The telemetry should show one font fingerprinting attempt.
+  await checkHistogram(TELEMETRY_FONT_FINGERPRINTING_PER_TAB, 1 /* true */, 1);
+
+  await clearTelemetry();
+});