trimming whitespace after deleting newline character + tests -- feature request microsoft#134898

Author: adityavc

src/vs/editor/common/cursor/cursorDeleteOperations.ts

@@ -177,15 +177,16 @@ export class DeleteOperations {
 		const endLineNumber = Math.max(startPosition.lineNumber, position.lineNumber);
 		let startColumn = position.column;
 		let endColumn = startPosition.column;
-		if (startLineNumber == startPosition.lineNumber) {
+		if (startLineNumber === startPosition.lineNumber) {
 			//top down deletion
 			startColumn = startPosition.column;
 			endColumn = position.column;
 		}
 		let firstNonWhiteSpaceColumn = model.getLineFirstNonWhitespaceColumn(endLineNumber);
 		let lastNonWhiteSpaceColumn = model.getLineLastNonWhitespaceColumn(startLineNumber);
-		if (startLineNumber != endLineNumber && model.getLineContent(startLineNumber).length > 0) {
-			//deleting new line character + trimming white space
+		//deleting new line character + trimming white space
+		if (startLineNumber !== endLineNumber && model.getLineContent(startLineNumber).length > 0) {
+			//expand delete range to include extra white space (last non whitespace char to first non white char on following line)
 			if (startColumn < lastNonWhiteSpaceColumn) {
 				lastNonWhiteSpaceColumn = startColumn;
 			}

src/vs/editor/test/browser/controller/cursor.test.ts

@@ -5570,6 +5570,30 @@ suite('Editor Controller', () => {
 		});
 	});
 
+	test('feature request - #134898: Trimming whitespace when deleting newline character', () => {
+		const model = createTextModel(
+			[
+				'Hello world!',
+				'    ',
+				'    another line'
+			].join('\n'),
+			undefined,
+			{
+				insertSpaces: false
+			},
+		);
+		withTestCodeEditor(model, {}, (editor, viewModel) => {
+			viewModel.setSelections('test', [new Selection(2, 5, 3, 1)]);
+			//when deleting middle empty line -- no text present so left spaces/tabs preserved
+			CoreEditingCommands.DeleteLeft.runEditorCommand(null, editor, null);
+			assert.strictEqual(model.getLineContent(2), '    another line');
+			//removes the extra white space in front of line 2 when deleting new line character
+			viewModel.setSelections('test', [new Selection(1, 13, 2, 1)]);
+			CoreEditingCommands.DeleteLeft.runEditorCommand(null, editor, null);
+			assert.strictEqual(model.getLineContent(1), 'Hello world!another line');
+		});
+	});
+
 	test('issue #78527 - does not close quote on odd count', () => {
 		usingCursor({
 			text: [