1 files changed, 77 insertions, 0 deletions
diff --git a/gfx/layers/apz/test/mochitest/browser_test_scroll_thumb_dragging.js b/gfx/layers/apz/test/mochitest/browser_test_scroll_thumb_dragging.js
new file mode 100644
index 0000000000..bd2d733a32
--- /dev/null
+++ b/gfx/layers/apz/test/mochitest/browser_test_scroll_thumb_dragging.js
@@ -0,0 +1,77 @@
+add_task(async function () {
+  function httpURL(filename) {
+    let chromeURL = getRootDirectory(gTestPath) + filename;
+    return chromeURL.replace(
+      "chrome://mochitests/content/",
+      "http://mochi.test:8888/"
+    );
+  }
+
+  const newWin = await BrowserTestUtils.openNewBrowserWindow();
+
+  const pageUrl = httpURL("helper_scroll_thumb_dragging.html");
+  const tab = await BrowserTestUtils.openNewForegroundTab(
+    newWin.gBrowser,
+    pageUrl
+  );
+
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+    await content.wrappedJSObject.promiseApzFlushedRepaints();
+    await content.wrappedJSObject.waitUntilApzStable();
+  });
+
+  // Send an explicit click event to make sure the new window accidentally
+  // doesn't get an "enter-notify-event" on Linux during dragging, the event
+  // forcibly cancels the dragging state.
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+    // Creating an object in this content privilege so that the object
+    // properties can be accessed in below
+    // promiseNativeMouseEventWithAPZAndWaitForEvent function.
+    const moveParams = content.window.eval(`({
+      target: window,
+      type: "mousemove",
+      offsetX: 10,
+      offsetY: 10
+    })`);
+    const clickParams = content.window.eval(`({
+      target: window,
+      type: "click",
+      offsetX: 10,
+      offsetY: 10
+    })`);
+    // Send a mouse move event first to make sure the "enter-notify-event"
+    // happens.
+    await content.wrappedJSObject.promiseNativeMouseEventWithAPZAndWaitForEvent(
+      moveParams
+    );
+    await content.wrappedJSObject.promiseNativeMouseEventWithAPZAndWaitForEvent(
+      clickParams
+    );
+  });
+
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+    const scrollPromise = new Promise(resolve => {
+      content.window.addEventListener("scroll", resolve, { once: true });
+    });
+    const dragFinisher =
+      await content.wrappedJSObject.promiseVerticalScrollbarDrag(
+        content.window,
+        10,
+        10
+      );
+
+    await scrollPromise;
+    await dragFinisher();
+
+    await content.wrappedJSObject.promiseApzFlushedRepaints();
+  });
+
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+    ok(
+      content.window.scrollY < 100,
+      "The root scrollable content shouldn't be scrolled too much"
+    );
+  });
+
+  await BrowserTestUtils.closeWindow(newWin);
+});