fix: stop the auto-updater installing twice in one process

src/auto-updater.js

@@ -9,17 +9,22 @@ export function createAutoUpdater({ currentVersion, repository, token, targetDir
   if (channel !== undefined && !["stable", "beta"].includes(channel)) throw new TypeError("channel: expected stable or beta");
   if (onUpdate !== undefined && typeof onUpdate !== "function") throw new TypeError("onUpdate: expected a function");
   let running;
+  let installedResult;
   async function check() {
     if (mode === "off") return Object.freeze({ status: "disabled" });
     if (running) return running;
+    // Files changed, but this process still runs the old code. Keep the first
+    // rollback backup and require restart before another install-mode check.
+    if (installedResult) return installedResult;
     running = (async () => {
       const update = await checkForUpdate({ currentVersion, repository, token, channel, platform, fetchImpl });
       if (!update.available) return Object.freeze({ status: "current", version: update.currentVersion });
       if (mode === "notify") { await onUpdate?.(update); return Object.freeze({ status: "available", ...update }); }
       const verified = await downloadVerifiedUpdate({ update, token, fetchImpl });
       const installed = await installVerifiedUpdate({ update: verified, targetDir });
+      installedResult = Object.freeze({ status: "installed", ...installed });
       await onUpdate?.({ ...update, ...installed });
-      return Object.freeze({ status: "installed", ...installed });
+      return installedResult;
     })().finally(() => { running = undefined; });
     return running;
   }

test/auto-updater-repeat-install.test.js

@@ -0,0 +1,36 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {mkdtemp,mkdir,writeFile,readFile,rm} from 'node:fs/promises';
+import {tmpdir} from 'node:os';
+import {join} from 'node:path';
+import {execFileSync} from 'node:child_process';
+import {createHash} from 'node:crypto';
+import {createAutoUpdater} from '../src/auto-updater.js';
+
+test('sequential API checks do not reinstall or replace the original rollback backup',async()=>{
+ const root=await mkdtemp(join(tmpdir(),'updater-repeat-'));
+ try{
+  const target=join(root,'app'),stage=join(root,'stage');
+  await mkdir(target);await writeFile(join(target,'original'),'old');
+  await mkdir(join(stage,'dist'),{recursive:true});await writeFile(join(stage,'dist','manifest.json'),'{"version":"0.3.0"}');
+  execFileSync('tar',['-czf',join(root,'update.tar.gz'),'-C',stage,'.']);
+  const bytes=await readFile(join(root,'update.tar.gz'));const hash=createHash('sha256').update(bytes).digest('hex');
+  let downloads=0,notifications=0;
+  const updater=createAutoUpdater({currentVersion:'0.2.0',repository:'o/r',channel:'stable',platform:'linux',mode:'install',targetDir:target,onUpdate:async()=>{notifications++;},fetchImpl:async url=>{
+   if(url.endsWith('/releases'))return Response.json([{tag_name:'v0.3.0',assets:[{name:'nowplaying-v0.3.0.tar.gz',url:'https://api.github.com/asset'},{name:'SHA256SUMS',url:'https://api.github.com/sums'}]}]);
+   if(url.endsWith('/sums'))return new Response(hash+'  nowplaying-v0.3.0.tar.gz');
+   downloads++;return new Response(bytes);
+  }});
+  const first=await updater.check();assert.equal(first.status,'installed');assert.equal(first.restartRequired,true);
+  assert.deepEqual(await updater.check(),first);
+  assert.equal(downloads,1);assert.equal(notifications,1);
+  assert.equal(await readFile(join(target+'.backup','original'),'utf8'),'old');
+ }finally{await rm(root,{recursive:true,force:true});}
+});
+
+test('notify mode continues checking against the running version',async()=>{
+ let checks=0,notifications=0;
+ const updater=createAutoUpdater({currentVersion:'0.2.0',repository:'o/r',channel:'stable',platform:'linux',mode:'notify',onUpdate:async()=>{notifications++;},fetchImpl:async()=>{checks++;return Response.json([{tag_name:'v0.3.0',assets:[{name:'nowplaying-v0.3.0.tar.gz',url:'https://api.github.com/asset'},{name:'SHA256SUMS',url:'https://api.github.com/sums'}]}]);}});
+ for(let i=0;i<2;i++){const result=await updater.check();assert.equal(result.status,'available');assert.equal(result.currentVersion,'0.2.0');}
+ assert.equal(checks,2);assert.equal(notifications,2);
+});