Allow aria-describedby overriding

Summary:
Currently it's not possible to have draft-js *not* emit an `aria-describedby` attribute. This diff allows the developer to remove it.

This attribute points to the generated DOM id of the placeholder. Currently even if no placeholder was specified **[minor bug]**.

I will need this in order to complete T67720986. It will also resolve this [GitHub issue](#1739).

Fixing the GitHub issue meant that I needed a way to have the generated placeholder ID as well as a second specified one. The special token "{{PLACEHOLDER}}" can be used inside the prop to be replaced with that generated ID.

Fixes #1739

Reviewed By: claudiopro

Differential Revision: D21808668

fbshipit-source-id: c27fe0fa8237518f1e2b6830cc8a3e13b3a9d8c7

src/component/base/DraftEditor.react.js

@@ -134,6 +134,7 @@ class UpdateDraftEditorFlags extends React.Component<{
  */
 class DraftEditor extends React.Component<DraftEditorProps, State> {
   static defaultProps: DraftEditorDefaultProps = {
+    ariaDescribedBy: '{{editor_id_placeholder}}',
     blockRenderMap: DefaultDraftBlockRenderMap,
     blockRendererFn: function() {
       return null;
@@ -314,6 +315,22 @@ class DraftEditor extends React.Component<DraftEditorProps, State> {
     return null;
   }
 
+  /**
+   * returns ariaDescribedBy prop with '{{editor_id_placeholder}}' replaced with
+   * the DOM id of the placeholder (if it exists)
+   * @returns aria-describedby attribute value
+   */
+  _renderARIADescribedBy(): ?string {
+    const describedBy = this.props.ariaDescribedBy || '';
+    const placeholderID = this._showPlaceholder()
+      ? this._placeholderAccessibilityID
+      : '';
+    return (
+      describedBy.replace('{{editor_id_placeholder}}', placeholderID) ||
+      undefined
+    );
+  }
+
   render(): React.Node {
     const {
       blockRenderMap,
@@ -381,9 +398,7 @@ class DraftEditor extends React.Component<DraftEditorProps, State> {
             }
             aria-autocomplete={readOnly ? null : this.props.ariaAutoComplete}
             aria-controls={readOnly ? null : this.props.ariaControls}
-            aria-describedby={
-              this.props.ariaDescribedBy || this._placeholderAccessibilityID
-            }
+            aria-describedby={this._renderARIADescribedBy()}
             aria-expanded={readOnly ? null : ariaExpanded}
             aria-label={this.props.ariaLabel}
             aria-labelledby={this.props.ariaLabelledBy}

src/component/base/DraftEditorProps.js

@@ -89,6 +89,12 @@ export type DraftEditorProps = {
   ariaActiveDescendantID?: string,
   ariaAutoComplete?: string,
   ariaControls?: string,
+  /**
+   * aria-describedby attribute. should point to the id of a descriptive
+   * element. The substring, "{{editor_id_placeholder}}" will be replaced with
+   * the DOM id of the placeholder element if it exists.
+   * @default "{{editor_id_placeholder}}"
+   */
   ariaDescribedBy?: string,
   ariaExpanded?: boolean,
   ariaLabel?: string,
@@ -175,6 +181,7 @@ export type DraftEditorProps = {
 };
 
 export type DraftEditorDefaultProps = {
+  ariaDescribedBy: string,
   blockRenderMap: DraftBlockRenderMap,
   blockRendererFn: (block: BlockNodeRecord) => ?Object,
   blockStyleFn: (block: BlockNodeRecord) => string,

src/component/base/__tests__/DraftEditor.react-test.js

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @emails oncall+draft_js
+ * @flow
  * @format
  */
 
@@ -13,18 +14,22 @@
 jest.mock('generateRandomKey');
 
 const DraftEditor = require('DraftEditor.react');
+const EditorState = require('EditorState');
 const React = require('React');
 
+// $FlowFixMe
 const ReactShallowRenderer = require('react-test-renderer/shallow');
 
 let shallow;
+let editorState;
 
 beforeEach(() => {
   shallow = new ReactShallowRenderer();
+  editorState = EditorState.createEmpty();
 });
 
 test('must has generated editorKey', () => {
-  shallow.render(<DraftEditor />);
+  shallow.render(<DraftEditor editorState={editorState} onChange={() => {}} />);
 
   // internally at Facebook we use a newer version of the shallowRenderer
   // which has a different level of wrapping of the '_instance'
@@ -36,7 +41,13 @@ test('must has generated editorKey', () => {
 });
 
 test('must has editorKey same as props', () => {
-  shallow.render(<DraftEditor editorKey="hash" />);
+  shallow.render(
+    <DraftEditor
+      editorState={editorState}
+      onChange={() => {}}
+      editorKey="hash"
+    />,
+  );
 
   // internally at Facebook we use a newer version of the shallowRenderer
   // which has a different level of wrapping of the '_instance'
@@ -46,3 +57,82 @@ test('must has editorKey same as props', () => {
     shallow._instance.getEditorKey || shallow._instance._instance.getEditorKey;
   expect(getEditorKey()).toMatchSnapshot();
 });
+
+describe('ariaDescribedBy', () => {
+  function getProps(elem) {
+    const r = shallow.render(elem);
+    const ec = r.props.children[1].props.children;
+    return ec.props;
+  }
+
+  describe('without placeholder', () => {
+    test('undefined by default', () => {
+      const props = getProps(
+        <DraftEditor editorState={editorState} onChange={() => {}} />,
+      );
+      expect(props).toHaveProperty('aria-describedby', undefined);
+    });
+
+    test('can be set to something arbitrary', () => {
+      const props = getProps(
+        <DraftEditor
+          editorState={editorState}
+          onChange={() => {}}
+          ariaDescribedBy="abc"
+        />,
+      );
+      expect(props).toHaveProperty('aria-describedby', 'abc');
+    });
+
+    test('can use special token', () => {
+      const props = getProps(
+        <DraftEditor
+          editorState={editorState}
+          onChange={() => {}}
+          ariaDescribedBy="abc {{editor_id_placeholder}} xyz"
+        />,
+      );
+      expect(props).toHaveProperty('aria-describedby', 'abc  xyz');
+    });
+  });
+
+  describe('with placeholder', () => {
+    test('has placeholder id by default', () => {
+      const props = getProps(
+        <DraftEditor
+          editorState={editorState}
+          onChange={() => {}}
+          editorKey="X"
+          placeholder="place"
+        />,
+      );
+      expect(props).toHaveProperty('aria-describedby', 'placeholder-X');
+    });
+
+    test('can be set to something arbitrary', () => {
+      const props = getProps(
+        <DraftEditor
+          editorState={editorState}
+          onChange={() => {}}
+          editorKey="X"
+          placeholder="place"
+          ariaDescribedBy="abc"
+        />,
+      );
+      expect(props).toHaveProperty('aria-describedby', 'abc');
+    });
+
+    test('can use special token', () => {
+      const props = getProps(
+        <DraftEditor
+          editorState={editorState}
+          onChange={() => {}}
+          editorKey="X"
+          placeholder="place"
+          ariaDescribedBy="abc {{editor_id_placeholder}} xyz"
+        />,
+      );
+      expect(props).toHaveProperty('aria-describedby', 'abc placeholder-X xyz');
+    });
+  });
+});

src/component/base/__tests__/__snapshots__/DraftEditor.react-test.js.snap

@@ -2,4 +2,4 @@
 
 exports[`must has editorKey same as props 1`] = `"hash"`;
 
-exports[`must has generated editorKey 1`] = `"key0"`;
+exports[`must has generated editorKey 1`] = `"key1"`;