chore: import upstream snapshot with attribution

packages/testing/src/setup/vitest.setup.ts

@@ -0,0 +1,40 @@
+/**
+ * Shared Vitest setup file for the testing package.
+ *
+ * Import this in your vitest.config.ts to get common mocks and setup.
+ *
+ * @example
+ * ```ts
+ * // vitest.config.ts
+ * export default defineConfig({
+ *   test: {
+ *     setupFiles: ['@sim/testing/setup'],
+ *   },
+ * })
+ * ```
+ */
+
+import { afterEach, beforeEach, vi } from 'vitest'
+import { setupGlobalFetchMock } from '../mocks/fetch.mock'
+import { createMockLogger } from '../mocks/logger.mock'
+import { clearStorageMocks, setupGlobalStorageMocks } from '../mocks/storage.mock'
+
+// Setup global storage mocks
+setupGlobalStorageMocks()
+
+// Setup global fetch mock with empty JSON response by default
+setupGlobalFetchMock({ json: {} })
+
+// Clear mocks between tests
+beforeEach(() => {
+  vi.clearAllMocks()
+})
+
+afterEach(() => {
+  clearStorageMocks()
+})
+
+// Export utilities for use in tests
+export { createMockLogger }
+export { setupGlobalStorageMocks, clearStorageMocks }
+export { mockFetchError, mockNextFetchResponse, setupGlobalFetchMock } from '../mocks/fetch.mock'