From 9ea296657e23a4483ee6304f7175d5491897ea93 Mon Sep 17 00:00:00 2001
From: Jaromir Obr <jaromir.obr@gmail.com>
Date: Wed, 17 Jun 2026 14:06:18 +0200
Subject: [PATCH] fix(typescript): unique temp file names to fix run-multiple
 race (#5642)
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Transpiled TypeScript files were written to a fixed "<source>.temp.mjs"
path next to the source. Under run-multiple, every forked worker transpiles
the same files to the same temp paths and cleans them up independently, so
one worker's cleanup deletes files the others still need to import — surfacing
as "Cannot find module *.temp.mjs".

Include process.pid plus a random suffix in the temp file name so each worker
writes (and removes) its own files. The names still end in ".temp.mjs", so
stack-trace remapping and fixErrorStack keep working.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 lib/utils/typescript.js            |  4 +++-
 test/unit/utils/typescript_test.js | 36 ++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 test/unit/utils/typescript_test.js

diff --git a/lib/utils/typescript.js b/lib/utils/typescript.js
index 5f9d0d417..3ee0fda7b 100644
--- a/lib/utils/typescript.js
+++ b/lib/utils/typescript.js
@@ -385,7 +385,9 @@ const __dirname = __dirname_fn(__filename);
     )
 
     // Write the transpiled file with updated imports
-    const tempFile = filePath.replace(/\.ts$/, '.temp.mjs')
+    // Include process.pid + a random suffix so concurrent run-multiple workers
+    // don't write to and delete each other's temp files (see issue #5642).
+    const tempFile = filePath.replace(/\.ts$/, `.${process.pid}.${Math.random().toString(36).slice(2, 10)}.temp.mjs`)
     fs.writeFileSync(tempFile, jsContent)
     transpiledFiles.set(filePath, tempFile)
   }
diff --git a/test/unit/utils/typescript_test.js b/test/unit/utils/typescript_test.js
new file mode 100644
index 000000000..5f57ca71a
--- /dev/null
+++ b/test/unit/utils/typescript_test.js
@@ -0,0 +1,36 @@
+import { expect } from 'chai'
+import { fileURLToPath } from 'url'
+import path from 'path'
+import { createRequire } from 'module'
+import { transpileTypeScript, cleanupTempFiles } from '../../../lib/utils/typescript.js'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+const require = createRequire(import.meta.url)
+const typescript = require('typescript')
+
+const configPath = path.resolve(__dirname, '../../data/typescript-config-imports/tests/api/codecept.conf.ts')
+
+describe('TypeScript transpilation', () => {
+  it('uses unique temp file names per invocation so concurrent run-multiple workers do not delete each other (#5642)', async () => {
+    const first = await transpileTypeScript(configPath, typescript)
+    const second = await transpileTypeScript(configPath, typescript)
+
+    try {
+      expect(first.allTempFiles.length).to.be.greaterThan(0)
+      expect(second.allTempFiles.length).to.equal(first.allTempFiles.length)
+
+      // Every temp file path is still recognisable as a transpiled file
+      for (const file of [...first.allTempFiles, ...second.allTempFiles]) {
+        expect(file).to.match(/\.temp\.mjs$/)
+      }
+
+      // The two invocations must not share any temp file path, otherwise one
+      // worker's cleanup would remove files the other still needs to import.
+      const shared = first.allTempFiles.filter(f => second.allTempFiles.includes(f))
+      expect(shared, `temp files were shared between invocations: ${shared}`).to.be.empty
+    } finally {
+      cleanupTempFiles(first.allTempFiles)
+      cleanupTempFiles(second.allTempFiles)
+    }
+  })
+})