Bug 1825611: Add test for overflow:hidden hittesting and acc creation r=Jamie

Differential Revision: https://phabricator.services.mozilla.com/D175196

accessible/tests/browser/hittest/browser_test_general.js

@@ -232,3 +232,47 @@ addAccessibleTask(
     iframeAttrs: { style: "width: 600px; height: 600px; padding: 10px;" },
   }
 );
+
+/**
+ * Verify that hit testing returns the proper accessible when one acc content
+ * is partially hidden due to overflow:hidden;
+ */
+addAccessibleTask(
+  `
+  <style>
+    div div {
+      overflow: hidden;
+      font-family: monospace;
+      width: 2ch;
+    }
+  </style>
+  <div id="container" style="display: flex; flex-direction: row-reverse;">
+    <div id="aNode">abcde</div><div id="fNode">fghij</div>
+  </div>`,
+  async function(browser, docAcc) {
+    const container = findAccessibleChildByID(docAcc, "container");
+    const aNode = findAccessibleChildByID(docAcc, "aNode");
+    const fNode = findAccessibleChildByID(docAcc, "fNode");
+    const dpr = await getContentDPR(browser);
+    const [, , containerWidth] = Layout.getBounds(container, dpr);
+    const [, , aNodeWidth] = Layout.getBounds(aNode, dpr);
+
+    await testChildAtPoint(
+      dpr,
+      containerWidth - 1,
+      1,
+      container,
+      aNode,
+      aNode.firstChild
+    );
+    await testChildAtPoint(
+      dpr,
+      containerWidth - aNodeWidth - 1,
+      1,
+      container,
+      fNode,
+      fNode.firstChild
+    );
+  },
+  { chrome: true, iframe: true, remoteIframe: true }
+);

accessible/tests/browser/tree/browser.ini

@@ -12,6 +12,7 @@ prefs =
 skip-if = true || (verify && !debug && (os == 'linux')) #Bug 1445513
 [browser_browser_element.js]
 [browser_css_content_visibility.js]
+[browser_general.js]
 [browser_lazy_tabs.js]
 [browser_searchbar.js]
 [browser_shadowdom.js]

accessible/tests/browser/tree/browser_general.js

+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+/**
+ * Verify adding `overflow:hidden;` styling to a div causes it to
+ * get an accessible.
+ */
+addAccessibleTask(`<p>hello world</p>`, async function(browser, docAcc) {
+  const originalTree = { DOCUMENT: [{ PARAGRAPH: [{ TEXT_LEAF: [] }] }] };
+
+  testAccessibleTree(docAcc, originalTree);
+  info("Adding div element");
+  await contentSpawnMutation(
+    browser,
+    { unexpected: [[EVENT_REORDER, docAcc]] },
+    function() {
+      const d = content.document.createElement("div");
+      content.document.body.appendChild(d);
+    }
+  );
+
+  testAccessibleTree(docAcc, originalTree);
+  info("Adding overflow:hidden styling to div");
+  await contentSpawnMutation(
+    browser,
+    { expected: [[EVENT_REORDER, docAcc]] },
+    function() {
+      content.document.body.lastElementChild.setAttribute(
+        "style",
+        "overflow:hidden;"
+      );
+    }
+  );
+
+  testAccessibleTree(docAcc, {
+    DOCUMENT: [{ PARAGRAPH: [{ TEXT_LEAF: [] }] }, { SECTION: [] }],
+  });
+});