Add basic canvas fingerprinting detection test.

Fixes #1268.

tests/selenium/fingerprinting_test.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+# -*- coding: UTF-8 -*-
+
+import unittest
+
+import pbtest
+
+
+class FingerprintingDetectionTest(pbtest.PBSeleniumTest):
+    """Tests to make sure fingerprinting detection works as expected."""
+
+    def detected_tracking(self, domain, page_url):
+        return self.js("""let tracker_origin = window.getBaseDomain("{}"),
+  site_origin = window.getBaseDomain(utils.makeURI("{}").host),
+  map = badger.storage.snitch_map.getItemClones();
+
+return (
+  map.hasOwnProperty(tracker_origin) &&
+    map[tracker_origin].indexOf(site_origin) != -1
+);""".format(domain, page_url))
+
+    def test_canvas_fingerprinting_detection(self):
+        PAGE_URL = (
+            "https://cdn.rawgit.com/ghostwords"
+            "/ff6347b93ec126d4f73a9ddfd8b09919/raw/2332f82d3982bd4a84cd2380aed90228955d1f2a"
+            "/privacy_badger_fingerprint_test_fixture.html"
+        )
+        FINGERPRINTING_DOMAIN = "cdn.jsdelivr.net"
+
+        # visit the page
+        self.load_url(PAGE_URL)
+
+        # open Badger's background page
+        self.open_window()
+        self.load_url(self.bg_url, wait_on_site=1)
+
+        # check that we detected the fingerprinting domain as a tracker
+        self.assertTrue(
+            self.detected_tracking(FINGERPRINTING_DOMAIN, PAGE_URL),
+            "Canvas fingerprinting resource was detected as a tracker."
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()