fix: keep selection on formatting

src/DocumentWatcher.ts

@@ -8,6 +8,7 @@ import {
 	TextEditorOptions,
 	window,
 	workspace,
+	WorkspaceEdit,
 } from 'vscode'
 import {
 	InsertFinalNewline,
@@ -75,18 +76,20 @@ export default class DocumentWatcher {
 				const activeEditor = window.activeTextEditor
 				const activeDoc = activeEditor?.document
 				if (activeDoc && activeDoc === e.document && activeEditor) {
-					selections = activeEditor.selections
+					selections = [...activeEditor.selections]
 				}
 				const transformations = this.calculatePreSaveTransformations(
 					e.document,
 					e.reason,
 				)
-				e.waitUntil(transformations)
-				if (selections.length) {
-					const edits = await transformations
-					if (activeEditor && edits.length) {
-						activeEditor.selections = selections
-					}
+
+				const workspaceEdit = new WorkspaceEdit()
+				const textEdits = await transformations
+				workspaceEdit.set(e.document.uri, textEdits)
+				await workspace.applyEdit(workspaceEdit)
+
+				if (activeEditor && textEdits.length && selections.length) {
+					activeEditor.selections = selections
 				}
 			}),
 		)

src/test/suite/index.test.ts

@@ -1,6 +1,6 @@
 import * as assert from 'assert'
 import * as os from 'os'
-import { Position, window, workspace, WorkspaceEdit } from 'vscode'
+import { Position, window, workspace, WorkspaceEdit, Uri } from 'vscode'
 import { getFixturePath, getOptionsForFixture, wait } from '../testUtils'
 
 import * as utils from 'vscode-test-utils'
@@ -284,22 +284,42 @@ suite('EditorConfig extension', function () {
 			`editor has insertSpaces: ${options.insertSpaces}`,
 		)
 	})
+
+	test('keep selection on format', async () => {
+		await withSetting('insert_final_newline', 'true', {
+			fileName: 'test-selection',
+		}).saveText('foobar')
+		assert(window.activeTextEditor, 'no active editor')
+
+                // Before saving, the selection is on line 0. This should remain unchanged.
+		assert.strictEqual(
+			window.activeTextEditor.selection.start.line,
+			0,
+			'editor selection start line changed',
+		)
+		assert.strictEqual(
+			window.activeTextEditor.selection.end.line,
+			0,
+			'editor selection end line changed',
+		)
+	})
 })
 
 function withSetting(
 	rule: string,
 	value: string,
 	options: {
 		contents?: string
+		fileName?: string
 	} = {},
 ) {
 	return {
 		async getText() {
-			return (await createDoc(options.contents)).getText()
+			return (await createDoc(options.contents, options.fileName)).getText()
 		},
 		saveText(text: string) {
 			return new Promise<string>(async resolve => {
-				const doc = await createDoc(options.contents)
+				const doc = await createDoc(options.contents, options.fileName)
 				workspace.onDidChangeTextDocument(doc.save)
 				workspace.onDidSaveTextDocument(savedDoc => {
 					assert.strictEqual(savedDoc.isDirty, false, 'dirty saved doc')
@@ -315,12 +335,16 @@ function withSetting(
 			})
 		},
 	}
+	async function createDoc(contents = '', name = 'test') {
+		const fixturePath = getFixturePath([rule, value, name])
 
-	async function createDoc(contents = '') {
-		const uri = await utils.createFile(
-			contents,
-			getFixturePath([rule, value, 'test']),
-		)
+		try {
+			await workspace.fs.delete(Uri.file(fixturePath))
+		} catch {
+			// ignore
+		}
+
+		const uri = await utils.createFile(contents, fixturePath)
 		const doc = await workspace.openTextDocument(uri)
 		await window.showTextDocument(doc)
 		await wait(50) // wait for EditorConfig to apply new settings