Desktop,Mobile: Fixes #12744: Fix adding lists to blank lines using toolbar buttons (#12745)

packages/editor/CodeMirror/markdown/markdownCommands.toggleList.test.ts

@@ -68,7 +68,7 @@ describe('markdownCommands.toggleList', () => {
 		const checklistEndText = ['- [ ] a', '- [ ] test'].join('\n');
 
 		const input = `${checklistStartText}\n\n${checklistEndText}`;
-		const expected = `${checklistStartText}\n\n${checklistEndText}`; // no change
+		const expected = `${checklistStartText}\n- [ ] \n${checklistEndText}`; // new item
 
 		const editor = await createTestEditor(
 			input,
@@ -466,4 +466,23 @@ A block quote:
 
 		expect(editor.state.doc.toString()).toBe(expectedDocText);
 	});
+
+	it.each([
+		[ListType.CheckList, '', '- [ ] '],
+		[ListType.OrderedList, '', '1. '],
+		[ListType.UnorderedList, '', '- '],
+		[ListType.UnorderedList, '> ', '> - '],
+		[ListType.UnorderedList, '# Test\n\n', '# Test\n\n- '],
+	])('should add lists when activated on an empty line or empty block quote (list type: %d, initial doc: %j)', async (
+		listType, originalDocument, expected,
+	) => {
+		const editor = await createTestEditor(
+			originalDocument,
+			EditorSelection.cursor(originalDocument.length),
+			[],
+		);
+
+		toggleList(listType)(editor);
+		expect(editor.state.doc.toString()).toBe(expected);
+	});
 });

packages/editor/CodeMirror/markdown/markdownCommands.ts

@@ -213,12 +213,28 @@ export const toggleList = (listType: ListType): Command => {
 			return ListAction.SwitchFormatting;
 		};
 
+		const areAllLinesBlankInRange = (fromLine: Line, toLine: Line) => {
+			for (let lineNumber = fromLine.number; lineNumber <= toLine.number; lineNumber++) {
+				const line = state.doc.line(lineNumber);
+
+				// Consider lines within block quotes with no other content to be blank (this
+				// command should behave similarly regardless of whether in or out of a block
+				// quote).
+				if (stripBlockquote(line).trim() !== '') {
+					return false;
+				}
+			}
+
+			return true;
+		};
+
 		const changes: TransactionSpec = state.changeByRange((sel: SelectionRange) => {
 			const lineRange = getNextLineRange(sel);
 			if (!lineRange) return { range: sel };
 			const { fromLine, toLine } = lineRange;
 			const baselineIndent = getBaselineIndent(fromLine, toLine);
 			const action = getAction(fromLine, toLine);
+			const allLinesBlank = areAllLinesBlankInRange(fromLine, toLine);
 
 			// Outermost list item number
 			let outerCounter = 1;
@@ -230,8 +246,18 @@ export const toggleList = (listType: ListType): Command => {
 			for (let lineNum = fromLine.number; lineNum <= toLine.number; lineNum++) {
 				const line = doc.line(lineNum);
 				const origLineContent = stripBlockquote(line);
-				if (origLineContent.trim() === '') {
+				const currentLineBlank = origLineContent.trim() === '';
-					continue; // skip blank lines
+
+				// To support changing the formatting of non-tight lists, skip blank lines within
+				// larger content. This allows changing the list format without adding a potentially
+				// large number of empty list items.
+				//
+				// However, if all lines are blank (e.g. if the cursor at the beginning of an empty)
+				// document, we're not changing the formatting of an existing list. In this case,
+				// skipping blank lines would cause the command to do nothing.
+				// See https://github.com/laurent22/joplin/pull/12745.
+				if (currentLineBlank && !allLinesBlank) {
+					continue;
 				}
 
 				// Content excluding the block quote start