[RNMobile] Add optional custom editor component to native test helper (…

…#38133)

* Add optional custom editor component to helper

* Add config options into initialize editor helper

* Document the initialize editor test helper

test/native/helpers.js

@@ -34,7 +34,16 @@ provideToNativeHtml.mockImplementation( ( html ) => {
 	serializedHtml = html;
 } );
 
-export function initializeEditor( props ) {
+/**
+ * Initialize an editor for test assertions.
+ *
+ * @param {Object}                    props               Properties passed to the editor component.
+ * @param {string}                    props.initialHtml   String of block editor HTML to parse and render.
+ * @param {Object}                    [options]           Configuration options for the editor.
+ * @param {import('react').ReactNode} [options.component] A specific editor component to render.
+ * @return {import('@testing-library/react-native').RenderAPI} A Testing Library screen.
+ */
+export function initializeEditor( props, { component = Editor } = {} ) {
 	// Portions of the React Native Animation API rely upon these APIs. However,
 	// Jest's 'legacy' fake timer mutate these globals, which breaks the Animated
 	// API. We preserve the original implementations to restore them later.
@@ -49,8 +58,9 @@ export function initializeEditor( props ) {
 	jest.useFakeTimers( 'legacy' );
 
 	// Arrange
+	const EditorComponent = component;
 	const screen = render(
-		<Editor
+		<EditorComponent
 			postId={ `post-id-${ uuid() }` }
 			postType="post"
 			initialTitle="test"