From 57c45dbb72d430bb7744cf697dab08b349925452 Mon Sep 17 00:00:00 2001
From: Jason Rasmussen <jason@rasm.me>
Date: Fri, 6 Nov 2026 08:17:38 -0500
Subject: [PATCH] fix(web): isolate unit test storage (#33021)

---
 web/test/unit/mocks/storage.ts | 27 +++++++++++++++++++++++++++
 web/test/unit/setup.ts         |  5 +++++
 2 files changed, 32 insertions(+)
 create mode 100644 web/test/unit/mocks/storage.ts

diff --git a/web/test/unit/mocks/storage.ts b/web/test/unit/mocks/storage.ts
new file mode 100644
index 000000000..721b00462
--- /dev/null
+++ b/web/test/unit/mocks/storage.ts
@@ -0,0 +1,27 @@
+export class MemoryStorage implements Storage {
+  private items = new Map<string, string>();
+
+  get length() {
+    return this.items.size;
+  }
+
+  key(index: number) {
+    return [...this.items.keys()][index] ?? null;
+  }
+
+  getItem(key: string) {
+    return this.items.get(key) ?? null;
+  }
+
+  setItem(key: string, value: string) {
+    this.items.set(key, value);
+  }
+
+  removeItem(key: string) {
+    this.items.delete(key);
+  }
+
+  clear() {
+    this.items.clear();
+  }
+}
diff --git a/web/test/unit/setup.ts b/web/test/unit/setup.ts
index cc029ba9c..af1963e91 100644
--- a/web/test/unit/setup.ts
+++ b/web/test/unit/setup.ts
@@ -1,5 +1,10 @@
+import { MemoryStorage } from '#test/unit/mocks/storage.ts';
 import { init } from 'svelte-i18n';
 
+for (const name of ['localStorage', 'sessionStorage']) {
+  Object.defineProperty(globalThis, name, { value: new MemoryStorage(), configurable: true });
+}
+
 beforeAll(async () => {
   await init({ fallbackLocale: 'dev' });
 });