Fix malformed Live Preview URL construction

src/connectionInfo/connection.ts

@@ -157,7 +157,8 @@ export class Connection extends Disposable {
 		const workspaceRoot = this.rootPath;
 
 		if (workspaceRoot && this._absPathInWorkspace(path)) {
-			return PathUtil.ConvertToPosixPath(path.substring(workspaceRoot.length));
+			const relativePath = PathUtil.ConvertToPosixPath(path.substring(workspaceRoot.length));
+			return relativePath.startsWith('/') || relativePath === '' ? relativePath : `/${relativePath}`;
 		} else {
 			return undefined;
 		}

src/editorPreview/webviewComm.ts

@@ -80,15 +80,19 @@ export class WebviewComm extends Disposable {
 	 * @param {string} hostURI the (optional) URI of the host; alternatively, the function will manually generate the connection manager's HTTP URI if not provided with it initially.
 	 * @returns {Promise<string>} a promise for the address for the content.
 	 */
-	public async constructAddress(
-		URLExt: string,
-		connection: Connection = this.currentConnection,
-		hostURI?: vscode.Uri,
-		windowId?: number | undefined,
-	): Promise<string> {
-		if (URLExt.length > 0 && URLExt[0] == '/') {
-			URLExt = URLExt.substring(1);
-		}
+	public async constructAddress(
+		URLExt: string,
+		connection: Connection = this.currentConnection,
+		hostURI?: vscode.Uri,
+		windowId?: number | undefined,
+	): Promise<string> {
+		if (/^https?:\/\//i.test(URLExt)) {
+			return URLExt;
+		}
+
+		if (URLExt.length > 0 && URLExt[0] == '/') {
+			URLExt = URLExt.substring(1);
+		}
 
 		if (!hostURI) {
 			hostURI = await this.resolveHost(connection);

src/test/suite/connectionInfo.test.ts

@@ -5,6 +5,7 @@
 import assert from 'assert';
 import sinon from 'sinon';
 import vscode from 'vscode';
+import { Connection } from '../../connectionInfo/connection';
 import { ConnectionManager } from '../../connectionInfo/connectionManager';
 import { PathUtil } from '../../utils/pathUtil';
 
@@ -87,6 +88,14 @@ describe('ConnectionInfo', () => {
 	});
 
 
+	it('should include a leading slash when workspace root already ends with a separator', () => {
+		const connection = new Connection(testWorkspaces[0], '', 3000, 3001, '127.0.0.1');
+		sandbox.stub(connection, 'rootPath').get(() => 'C:\\Users\\TestUser\\workspace1\\');
+
+		assert.deepEqual(connection.getFileRelativeToWorkspace('C:\\Users\\TestUser\\workspace1\\index.html'), '/index.html');
+
+		connection.dispose();
+	});
 	it('should be able to create a Connection with an undefined workspace', async () => {
 		const target = sinon.spy();
 		sandbox.stub(SettingUtil, 'GetConfig').returns(makeSetting({}));
@@ -116,4 +125,4 @@ describe('ConnectionInfo', () => {
 			}
 		], target.args[0]);
 	});
-});
+});

src/test/suite/preview.test.ts

@@ -95,4 +95,12 @@ describe('PreviewManager', () => {
 		assert.ok(executeCommand.calledOnce);
 		assert.ok(executeCommand.getCall(0).calledWith('extension.js-debug.debugLink', `http://${connection.host}:${connection.httpPort}/index.html`));
 	});
-});
+
+	it("does not prefix absolute URLs with the preview host", async () => {
+		const webviewComm = Object.create(WebviewComm.prototype) as WebviewComm;
+		const hostUri = vscode.Uri.parse(`http://${connection.host}:${connection.httpPort}/`);
+
+		assert.equal(await webviewComm.constructAddress('http://example.test/page.html', connection, hostUri), 'http://example.test/page.html');
+		assert.equal(await webviewComm.constructAddress('https://example.test/page.html', connection, hostUri), 'https://example.test/page.html');
+	});
+});