fix (buildifier): Handle relative buildifier path without warning (#387)

Relative paths for buildifier are now supported as of v0.10.0, the
warning should not be shown when the buildifier executable exists at the
relative path specified.

Author: ryanwilsonperkin

src/buildifier/buildifier_availability.ts

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import * as fs from "fs/promises";
+import * as path from "path";
 import * as vscode from "vscode";
 import * as which from "which";
 
@@ -20,6 +22,15 @@ import {
   getDefaultBuildifierExecutablePath,
 } from "./buildifier";
 
+async function fileExists(filename: string) {
+  try {
+    await fs.stat(filename);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
 /** The URL to load for buildifier's releases. */
 const BUILDTOOLS_RELEASES_URL =
   "https://github.com/bazelbuild/buildtools/releases";
@@ -33,9 +44,20 @@ const BUILDTOOLS_RELEASES_URL =
  */
 export async function checkBuildifierIsAvailable() {
   const buildifierExecutable = getDefaultBuildifierExecutablePath();
+
   // Check if the program exists (in case it's an actual executable and not
   // an target name starting with `@`).
-  if (!buildifierExecutable.startsWith("@")) {
+  const isTarget = buildifierExecutable.startsWith("@");
+
+  // Check if the program exists as a relative path of the workspace
+  const pathExists = await fileExists(
+    path.join(
+      vscode.workspace.workspaceFolders?.[0]?.uri?.fsPath,
+      buildifierExecutable,
+    ),
+  );
+
+  if (!isTarget && !pathExists) {
     try {
       await which(buildifierExecutable);
     } catch (e) {