Fix link back to editor from revisions screen

editor/components/post-last-revision/check.js

@@ -6,10 +6,10 @@ import { connect } from 'react-redux';
 /**
  * Internal dependencies
  */
-import { getCurrentPostLastRevisionId } from '../../selectors';
+import { getCurrentPostLastRevisionId, getCurrentPostRevisionsCount } from '../../selectors';
 
-function PostLastRevisionCheck( { lastRevisionId, children } ) {
-	if ( ! lastRevisionId ) {
+export function PostLastRevisionCheck( { lastRevisionId, revisionsCount, children } ) {
+	if ( ! lastRevisionId || revisionsCount < 2 ) {
 		return null;
 	}
 
@@ -20,6 +20,7 @@ export default connect(
 	( state ) => {
 		return {
 			lastRevisionId: getCurrentPostLastRevisionId( state ),
+			revisionsCount: getCurrentPostRevisionsCount( state ),
 		};
 	}
 )( PostLastRevisionCheck );

editor/components/post-last-revision/index.js

@@ -24,7 +24,7 @@ function LastRevision( { lastRevisionId, revisionsCount } ) {
 	return (
 		<PostLastRevisionCheck>
 			<IconButton
-				href={ getWPAdminURL( 'revision.php', { revision: lastRevisionId } ) }
+				href={ getWPAdminURL( 'revision.php', { revision: lastRevisionId, gutenberg: true } ) }
 				className="editor-post-last-revision__title"
 				icon="backup"
 			>

editor/components/post-last-revision/test/check.js

@@ -0,0 +1,41 @@
+/**
+ * External dependencies
+ */
+import { shallow } from 'enzyme';
+
+/**
+ * Internal dependencies
+ */
+import { PostLastRevisionCheck } from '../check';
+
+describe( 'PostLastRevisionCheck', () => {
+	it( 'should not render anything if the last revision ID is unknown', () => {
+		const wrapper = shallow(
+			<PostLastRevisionCheck revisionsCount={ 2 }>
+				Children
+			</PostLastRevisionCheck>
+		);
+
+		expect( wrapper.type() ).toBe( null );
+	} );
+
+	it( 'should not render anything if there is only one revision', () => {
+		const wrapper = shallow(
+			<PostLastRevisionCheck lastRevisionId={ 1 } revisionsCount={ 1 }>
+				Children
+			</PostLastRevisionCheck>
+		);
+
+		expect( wrapper.type() ).toBe( null );
+	} );
+
+	it( 'should render if there are two revisions', () => {
+		const wrapper = shallow(
+			<PostLastRevisionCheck lastRevisionId={ 1 } revisionsCount={ 2 }>
+				Children
+			</PostLastRevisionCheck>
+		);
+
+		expect( wrapper.text() ).toEqual( 'Children' );
+	} );
+} );

lib/register.php

@@ -480,18 +480,42 @@ function gutenberg_redirect_to_classic_editor_when_saving_posts( $url ) {
 add_filter( 'redirect_post_location', 'gutenberg_redirect_to_classic_editor_when_saving_posts', 10, 1 );
 
 /**
- * Appends a query argument to the edit url to make sure it gets redirected to the classic editor.
+ * Appends a query argument to the edit url to make sure it is redirected to
+ * the editor from which the user navigated.
  *
  * @since 1.5.2
  *
  * @param string $url Edit url.
  * @return string Edit url.
  */
-function gutenberg_link_revisions_to_classic_editor( $url ) {
+function gutenberg_revisions_link_to_editor( $url ) {
 	global $pagenow;
-	if ( 'revision.php' === $pagenow ) {
-		$url = add_query_arg( 'classic-editor', '', $url );
+	if ( 'revision.php' !== $pagenow || isset( $_REQUEST['gutenberg'] ) ) {
+		return $url;
 	}
-	return $url;
+
+	return add_query_arg( 'classic-editor', '', $url );
+}
+add_filter( 'get_edit_post_link', 'gutenberg_revisions_link_to_editor' );
+
+/**
+ * Modifies revisions data to preserve Gutenberg argument used in determining
+ * where to redirect user returning to editor.
+ *
+ * @since 1.9.0
+ *
+ * @param array $revisions_data The bootstrapped data for the revisions screen.
+ * @return array Modified bootstrapped data for the revisions screen.
+ */
+function gutenberg_revisions_restore( $revisions_data ) {
+	if ( isset( $_REQUEST['gutenberg'] ) ) {
+		$revisions_data['restoreUrl'] = add_query_arg(
+			'gutenberg',
+			$_REQUEST['gutenberg'],
+			$revisions_data['restoreUrl']
+		);
+	}
+
+	return $revisions_data;
 }
-add_filter( 'get_edit_post_link', 'gutenberg_link_revisions_to_classic_editor' );
+add_filter( 'wp_prepare_revision_for_js', 'gutenberg_revisions_restore' );

phpunit/class-admin-test.php

@@ -116,4 +116,41 @@ function test_add_gutenberg_post_state() {
 		$post_states = apply_filters( 'display_post_states', array(), get_post( self::$post_without_blocks ) );
 		$this->assertEquals( array(), $post_states );
 	}
+
+	/**
+	 * Test that the revisions 'return to editor' links are set correctly for Classic & Gutenberg editors.
+	 *
+	 * @covers gutenberg_revisions_link_to_editor
+	 */
+	function test_gutenberg_revisions_link_to_editor() {
+		global $pagenow;
+
+		// Set up $pagenow so the filter will work.
+		$pagenow = 'revision.php';
+
+		// Test the filter when Gutenberg is the active editor.
+		$_REQUEST['gutenberg'] = '1';
+		$link                  = apply_filters( 'get_edit_post_link', 'http://test.com' );
+		$this->assertEquals( 'http://test.com', $link );
+
+		// Test the filter when Gutenberg is not the active editor.
+		unset( $_REQUEST['gutenberg'] );
+		$link = apply_filters( 'get_edit_post_link', 'http://test.com' );
+		$this->assertEquals( 'http://test.com?classic-editor', $link );
+	}
+
+	/**
+	 * Test that the revisions 'restore this revision' button links correctly for Classic & Gutenberg editors.
+	 */
+	function test_gutenberg_revisions_restore() {
+		// Test the filter when Gutenberg is the active editor.
+		$_REQUEST['gutenberg'] = '1';
+		$link                  = apply_filters( 'wp_prepare_revision_for_js', array( 'restoreUrl' => 'http://test.com' ) );
+		$this->assertEquals( array( 'restoreUrl' => 'http://test.com?gutenberg=1' ), $link );
+
+		// Test the filter when Gutenberg is not the active editor.
+		unset( $_REQUEST['gutenberg'] );
+		$link = apply_filters( 'wp_prepare_revision_for_js', array( 'restoreUrl' => 'http://test.com' ) );
+		$this->assertEquals( array( 'restoreUrl' => 'http://test.com' ), $link );
+	}
 }