From 72eb4f6f5dd565dfd86f56a8774665f669f79a4d Mon Sep 17 00:00:00 2001
From: Maximilian Antoni <mail@maxantoni.de>
Date: Fri, 2 Aug 2024 07:51:46 +0200
Subject: [PATCH] Resolve timing issue with reading config

---
 lib/config.js      |  7 ++++++-
 lib/config.test.js | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/config.js b/lib/config.js
index 8ebe5fd..0e1528d 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -17,8 +17,13 @@ import fs from 'node:fs/promises';
  * @returns {Promise<Config | null>}
  */
 export async function loadConfig(resolver) {
+  const filename = configFile(resolver);
   try {
-    const raw = await fs.readFile(configFile(resolver), 'utf8');
+    let raw = await fs.readFile(filename, 'utf8');
+    if (!raw) {
+      await new Promise((resolve) => setTimeout(resolve, 50));
+      raw = await fs.readFile(filename, 'utf8');
+    }
     const [token, port, pid, hash] = raw.split(' ');
     return { token, port: Number(port), pid: Number(pid), hash };
   } catch {
diff --git a/lib/config.test.js b/lib/config.test.js
index 0873752..0854014 100644
--- a/lib/config.test.js
+++ b/lib/config.test.js
@@ -39,6 +39,29 @@ describe('lib/config', () => {
 
       await assert.resolves(promise, null);
     });
+
+    it('retries reading the file if content was empty', async () => {
+      const clock = sinon.useFakeTimers();
+      const contents = ['', 'token 123 456 hash'];
+      sinon.replace(
+        fs,
+        'readFile',
+        sinon.fake(() => Promise.resolve(contents.shift()))
+      );
+
+      const promise = loadConfig(resolver);
+      await Promise.resolve();
+      assert.calledOnce(fs.readFile);
+      clock.tick(50);
+
+      await assert.resolves(promise, {
+        token: 'token',
+        port: 123,
+        pid: 456,
+        hash: 'hash'
+      });
+      assert.calledTwice(fs.readFile);
+    });
   });
 
   context('writeConfig', () => {