1 files changed, 85 insertions, 0 deletions
diff --git a/dom/events/test/bug418986-3.js b/dom/events/test/bug418986-3.js
new file mode 100644
index 0000000000..81d04b9b22
--- /dev/null
+++ b/dom/events/test/bug418986-3.js
@@ -0,0 +1,85 @@
+SimpleTest.waitForExplicitFinish();
+
+// The main testing function.
+var test = async function (isContent) {
+  await SpecialPowers.contentTransformsReceived(window);
+
+  // Each definition is [eventType, prefSetting]
+  // Where we are setting the "privacy.resistFingerprinting" pref.
+  let eventDefs = [
+    ["mousedown", true],
+    ["mouseup", true],
+    ["mousedown", false],
+    ["mouseup", false],
+  ];
+
+  let testCounter = 0;
+
+  // Declare ahead of time.
+  let setup;
+
+  // This function is called when the event handler fires.
+  let handleEvent = function (event, prefVal) {
+    let resisting = prefVal && isContent;
+    if (resisting) {
+      is(
+        event.screenX,
+        event.clientX,
+        "event.screenX and event.clientX should be the same"
+      );
+      is(
+        event.screenY,
+        event.clientY,
+        "event.screenY and event.clientY should be the same"
+      );
+    } else {
+      // We can't be sure about X coordinates not being equal, but we can test Y.
+      isnot(event.screenY, event.clientY, "event.screenY !== event.clientY");
+    }
+    ++testCounter;
+    if (testCounter < eventDefs.length) {
+      nextTest();
+    } else {
+      SimpleTest.finish();
+    }
+  };
+
+  // In this function, we set up the nth div and event handler,
+  // and then synthesize a mouse event in the div, to test
+  // whether the resulting events resist fingerprinting by
+  // suppressing absolute screen coordinates.
+  nextTest = function () {
+    let [eventType, prefVal] = eventDefs[testCounter];
+    SpecialPowers.pushPrefEnv(
+      { set: [["privacy.resistFingerprinting", prefVal]] },
+      function () {
+        // The following code creates a new div for each event in eventDefs,
+        // attaches a listener to listen for the event, and then generates
+        // a fake event at the center of the div.
+        let div = document.createElementNS(
+          "http://www.w3.org/1999/xhtml",
+          "div"
+        );
+        div.style.width = "10px";
+        div.style.height = "10px";
+        div.style.backgroundColor = "red";
+        // Name the div after the event we're listening for.
+        div.id = eventType;
+        document.getElementById("body").appendChild(div);
+        // Seems we can't add an event listener in chrome unless we run
+        // it in a later task.
+        window.setTimeout(function () {
+          div.addEventListener(eventType, event => handleEvent(event, prefVal));
+          // For some reason, the following synthesizeMouseAtCenter call only seems to run if we
+          // wrap it in a window.setTimeout(..., 0).
+          window.setTimeout(function () {
+            synthesizeMouseAtCenter(div, { type: eventType });
+          }, 0);
+        }, 0);
+      }
+    );
+  };
+
+  // Now run by starting with the 0th event.
+  nextTest();
+};