Fix (indent): blockIndent now works with custom headings. Closes cked…

…itor#8177.

packages/ckeditor5-indent/src/indentblock.js

@@ -79,8 +79,10 @@ export default class IndentBlock extends Plugin {
 		const indentCommand = editor.commands.get( 'indent' );
 		const outdentCommand = editor.commands.get( 'outdent' );
 
-		// Enable block indentation by default in paragraph and default headings.
-		const knownElements = [ 'paragraph', 'heading1', 'heading2', 'heading3', 'heading4', 'heading5', 'heading6' ];
+		// Enable block indentation to headging configuration options. If it is not defined enable in paragraph and default headings.
+		const options = editor.config.get( 'heading.options' );
+		const headings = options && options.map( option => option.model );
+		const knownElements = headings || [ 'paragraph', 'heading1', 'heading2', 'heading3', 'heading4', 'heading5', 'heading6' ];
 
 		knownElements.forEach( elementName => {
 			if ( schema.isRegistered( elementName ) ) {

packages/ckeditor5-indent/tests/indentblock-integration.js

@@ -71,6 +71,49 @@ describe( 'IndentBlock - integration', () => {
 		} );
 	} );
 
+	// https://github.com/ckeditor/ckeditor5/issues/8177
+	describe( 'with custom heading', () => {
+		beforeEach( () => {
+			return createTestEditor( {
+				plugins: [ Paragraph, HeadingEditing, IndentEditing, IndentBlock ],
+				indentBlock: { offset: 50, unit: 'px' },
+				heading: {
+					options: [
+						{ model: 'paragraph', title: 'Paragraph', class: 'ck-heading_paragraph' },
+						{ model: 'heading1', view: 'h1', title: 'Heading 1', class: 'ck-heading_heading1' },
+						{ model: 'heading2', view: 'h2', title: 'Heading 2', class: 'ck-heading_heading2' },
+						{
+							model: 'headingFancy',
+							view: {
+								name: 'h2',
+								classes: 'fancy'
+							},
+							title: 'Heading 2 (fancy)',
+							class: 'ck-heading_heading2_fancy',
+							converterPriority: 'high'
+						}
+					]
+				}
+			} ).then( newEditor => {
+				editor = newEditor;
+				doc = editor.model.document;
+			} );
+		} );
+
+		it( 'should work with custom (user defined) headings', () => {
+			editor.setData( '<h2 class="fancy" style="margin-left:150px">foo</h2>' );
+
+			const customHeading = doc.getRoot().getChild( 0 );
+
+			expect( customHeading.hasAttribute( 'blockIndent' ) ).to.be.true;
+			expect( customHeading.getAttribute( 'blockIndent' ) ).to.equal( '150px' );
+
+			expect( editor.getData() ).to.equal( '<h2 class="fancy" style="margin-left:150px;">foo</h2>' );
+			expect( getViewData( editor.editing.view, { withoutSelection: true } ) )
+				.to.equal( '<h2 class="fancy" style="margin-left:150px">foo</h2>' );
+		} );
+	} );
+
 	// https://github.com/ckeditor/ckeditor5/issues/2359
 	it( 'should work with paragraphs regardless of plugin order', () => {
 		return createTestEditor( {