From 08f51f5ee95fab6e818391e0bc827ba43b49a232 Mon Sep 17 00:00:00 2001
From: Vladimir Sheremet <sleuths.slews0s@icloud.com>
Date: Mon, 2 Oct 2023 15:29:27 +0200
Subject: [PATCH] fix(happy-dom): don't crash when calling useFakeTimers with
 empty config

---
 packages/vitest/src/integrations/vi.ts        |  2 +-
 test/core/test/environments/happy-dom.spec.ts | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 test/core/test/environments/happy-dom.spec.ts

diff --git a/packages/vitest/src/integrations/vi.ts b/packages/vitest/src/integrations/vi.ts
index 3ab325321b77..0ad02b3058f2 100644
--- a/packages/vitest/src/integrations/vi.ts
+++ b/packages/vitest/src/integrations/vi.ts
@@ -217,7 +217,7 @@ function createVitest(): VitestUtils {
       }
 
       if (config)
-        _timers.configure(config)
+        _timers.configure({ ...workerState.config.fakeTimers, ...config })
       else
         _timers.configure(workerState.config.fakeTimers)
 
diff --git a/test/core/test/environments/happy-dom.spec.ts b/test/core/test/environments/happy-dom.spec.ts
new file mode 100644
index 000000000000..ecb80ade1c9e
--- /dev/null
+++ b/test/core/test/environments/happy-dom.spec.ts
@@ -0,0 +1,11 @@
+// @vitest-environment happy-dom
+
+import { afterEach, test, vi } from 'vitest'
+
+afterEach(() => {
+  vi.useRealTimers()
+})
+
+test('fake timers don\'t fail when using empty config', () => {
+  vi.useFakeTimers({})
+})