From 324bdc666f59815619b1d4c3c0a9fc17834df572 Mon Sep 17 00:00:00 2001
From: Aaron Cannon <cannona@fireantproductions.com>
Date: Mon, 6 Apr 2020 10:01:29 -0500
Subject: [PATCH] dialog: added support for the ariaHideAncestors prop.

---
 packages/dialog/__tests__/dialog.test.tsx | 53 ++++++++++++++++++++++-
 packages/dialog/src/index.tsx             | 30 ++++++++++---
 2 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/packages/dialog/__tests__/dialog.test.tsx b/packages/dialog/__tests__/dialog.test.tsx
index 31e8ce471..e2aeb2d10 100644
--- a/packages/dialog/__tests__/dialog.test.tsx
+++ b/packages/dialog/__tests__/dialog.test.tsx
@@ -4,7 +4,7 @@ import { useFakeTimers, SinonFakeTimers } from "sinon";
 import { axe, toHaveNoViolations } from "jest-axe";
 import { fireEvent, render, act, userEvent } from "$test/utils";
 import { AxeResults } from "$test/types";
-import { Dialog } from "@reach/dialog";
+import { Dialog, DialogProps } from "@reach/dialog";
 
 function getOverlay(container: Element) {
   return container.querySelector("[data-reach-dialog-overlay]");
@@ -58,6 +58,39 @@ describe("<Dialog />", () => {
       );
       expect(label).toHaveTextContent("I am the title now");
     });
+
+    it("ARIA hides ancestors by default", async () => {
+      const { findByTestId } = render(
+        <>
+          <div data-testid="sibling">Hidden</div>
+          <BasicOpenDialog />
+        </>
+      );
+      const sibling = await findByTestId("sibling");
+      expect(isAriaHidden(sibling)).toBe(true);
+    });
+
+    it("ARIA hides ancestors when ariaHideAncestors is true", async () => {
+      const { findByTestId } = render(
+        <>
+          <div data-testid="sibling">Hidden</div>
+          <BasicOpenDialog ariaHideAncestors={true} />
+        </>
+      );
+      const sibling = await findByTestId("sibling");
+      expect(isAriaHidden(sibling)).toBe(true);
+    });
+
+    it("doesn't ARIA hide ancestors when ariaHideAncestors is false", async () => {
+      const { findByTestId } = render(
+        <>
+          <div data-testid="sibling">Not hidden</div>
+          <BasicOpenDialog ariaHideAncestors={false} />
+        </>
+      );
+      const sibling = findByTestId("sibling");
+      expect(isAriaHidden(sibling)).toBe(false);
+    });
   });
 
   describe("user events", () => {
@@ -83,7 +116,7 @@ describe("<Dialog />", () => {
   });
 });
 
-function BasicOpenDialog() {
+function BasicOpenDialog(props: DialogProps) {
   const [showDialog, setShowDialog] = useState(true);
   return (
     <div>
@@ -92,6 +125,7 @@ function BasicOpenDialog() {
         aria-label="Announcement"
         isOpen={showDialog}
         onDismiss={() => setShowDialog(false)}
+        {...props}
       >
         <div data-testid="inner">
           <button onClick={() => setShowDialog(false)}>Close Dialog</button>
@@ -102,3 +136,18 @@ function BasicOpenDialog() {
     </div>
   );
 }
+
+/**
+ * Checks the element and its ancestors for an aria-hidden attribute.
+ * If an aria-hidden is found, we assume it is set to true, which should be a
+ * reasonable assumption for the purposes of these tests.
+ */
+function isAriaHidden(el?: HTMLElement) {
+  while (el) {
+    if (el.hasAttribute("aria-hidden")) {
+      return true;
+    }
+    el = el.parentElement;
+  }
+  return false;
+}
diff --git a/packages/dialog/src/index.tsx b/packages/dialog/src/index.tsx
index 31c009716..d7c4f9097 100644
--- a/packages/dialog/src/index.tsx
+++ b/packages/dialog/src/index.tsx
@@ -28,6 +28,7 @@ const overlayPropTypes = {
   initialFocusRef: () => null,
   allowPinchZoom: PropTypes.bool,
   onDismiss: PropTypes.func,
+  ariaHideAncestors: PropTypes.bool,
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -92,6 +93,7 @@ const DialogInner = forwardRef<HTMLDivElement, DialogProps>(
       onDismiss = noop,
       onMouseDown,
       onKeyDown,
+      ariaHideAncestors,
       ...props
     },
     forwardedRef
@@ -124,11 +126,11 @@ const DialogInner = forwardRef<HTMLDivElement, DialogProps>(
       mouseDownTarget.current = event.target;
     }
 
-    useEffect(
-      () =>
-        overlayNode.current ? createAriaHider(overlayNode.current) : void null,
-      []
-    );
+    useEffect(() => {
+      if (overlayNode.current && ariaHideAncestors) {
+        createAriaHider(overlayNode.current);
+      }
+    }, [ariaHideAncestors]);
 
     return (
       <FocusLock autoFocus returnFocus onActivation={activateFocusLock}>
@@ -225,7 +227,14 @@ if (__DEV__) {
  * @see Docs https://reacttraining.com/reach-ui/dialog#dialog
  */
 export const Dialog = forwardRef<HTMLDivElement, DialogProps>(function Dialog(
-  { isOpen, onDismiss = noop, initialFocusRef, allowPinchZoom, ...props },
+  {
+    isOpen,
+    onDismiss = noop,
+    initialFocusRef,
+    allowPinchZoom,
+    ariaHideAncestors = true,
+    ...props
+  },
   forwardedRef
 ) {
   return (
@@ -234,6 +243,7 @@ export const Dialog = forwardRef<HTMLDivElement, DialogProps>(function Dialog(
       allowPinchZoom={allowPinchZoom}
       isOpen={isOpen}
       onDismiss={onDismiss}
+      ariaHideAncestors={ariaHideAncestors}
     >
       <DialogContent ref={forwardedRef} {...props} />
     </DialogOverlay>
@@ -265,6 +275,13 @@ export type DialogProps = {
    * @see Docs https://reacttraining.com/reach-ui/dialog#dialog-ondismiss
    */
   onDismiss?: (event?: React.SyntheticEvent) => void;
+  /**
+   * By default, all of the nodes at the document.body root hav aria-hidden set
+   * on them, except for the currently active dialog.
+   *
+   * @see Docs https://reacttraining.com/reach-ui/dialog#aria-hiding-other-elements
+   */
+  ariaHideAncestors?: boolean;
   /**
    * Accepts any renderable content.
    *
@@ -287,6 +304,7 @@ if (__DEV__) {
     onDismiss: PropTypes.func,
     "aria-label": ariaLabelType,
     "aria-labelledby": ariaLabelType,
+    ariaHideAncestors: PropTypes.bool,
   };
 }