Use vscode.workspace.fs.stat to check file existence asynchronously

Author: andyleejordan

src/features/Examples.ts

@@ -1,25 +1,21 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-import * as fs from "fs";
 import path = require("path");
+import utils = require("../utils")
 import vscode = require("vscode");
 
 export class ExamplesFeature implements vscode.Disposable {
     private command: vscode.Disposable;
-    private examplesPath: string;
+    private examplesPath: vscode.Uri;
 
     constructor() {
-        this.examplesPath = path.resolve(__dirname, "../examples");
+        this.examplesPath = vscode.Uri.file(path.resolve(__dirname, "../examples"));
         this.command = vscode.commands.registerCommand("PowerShell.OpenExamplesFolder", () => {
-            vscode.commands.executeCommand(
-                "vscode.openFolder",
-                vscode.Uri.file(this.examplesPath),
-                true);
-
+            vscode.commands.executeCommand("vscode.openFolder", this.examplesPath, true);
             // Return existence of the path for testing. The `vscode.openFolder`
             // command should do this, but doesn't (yet).
-            return fs.existsSync(this.examplesPath)
+            return utils.fileExists(this.examplesPath);
         });
     }
 

src/features/PesterTests.ts

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 import * as path from "path";
-import * as fs from "fs";
 import vscode = require("vscode");
 import { SessionManager } from "../session";
 import Settings = require("../settings");
@@ -144,7 +143,7 @@ export class PesterTestsFeature implements vscode.Disposable {
         //
         // Ensure the necessary script exists (for testing). The debugger will
         // start regardless, but we also pass its success along.
-        return fs.existsSync(this.invokePesterStubScriptPath)
+        return utils.fileExists(this.invokePesterStubScriptPath)
             && vscode.debug.startDebugging(vscode.workspace.workspaceFolders[0], launchConfig);
     }
 }

src/utils.ts

@@ -6,12 +6,14 @@
 import fs = require("fs");
 import os = require("os");
 import path = require("path");
+import vscode = require("vscode");
 
 export const PowerShellLanguageId = "powershell";
 
-export function ensurePathExists(targetPath: string) {
+export function ensurePathExists(targetPath: string): void {
     // Ensure that the path exists
     try {
+        // TODO: Use vscode.workspace.fs
         fs.mkdirSync(targetPath);
     } catch (e) {
         // If the exception isn't to indicate that the folder exists already, rethrow it.
@@ -21,6 +23,23 @@ export function ensurePathExists(targetPath: string) {
     }
 }
 
+// Check that the file exists in an asynchronous manner that relies solely on the VS Code API, not Node's fs library.
+export async function fileExists(targetPath: string | vscode.Uri): Promise<boolean> {
+    try {
+            await vscode.workspace.fs.stat(
+                targetPath instanceof vscode.Uri
+                    ? targetPath
+                    : vscode.Uri.file(targetPath));
+        return true;
+    } catch (e) {
+        if (e instanceof vscode.FileSystemError.FileNotFound) {
+            return false;
+        }
+        throw e;
+    }
+
+}
+
 export function getPipePath(pipeName: string) {
     if (os.platform() === "win32") {
         return "\\\\.\\pipe\\" + pipeName;