test: isolate test files and restore test-scoped spies

src/__helpers__/restore-test-spies.setup.ts

@@ -0,0 +1,45 @@
+import { afterEach, beforeEach, type MockInstance, vi } from 'vitest';
+
+/**
+ * Restore spies created inside a test (or its hooks) after each test.
+ *
+ * The suite intentionally keeps some spies at module scope (inside `describe`
+ * blocks) so every test in the file reuses them; a global `restoreMocks` would
+ * tear those down after the first test. Track spies instead: module-scope spies
+ * are created before the first `beforeEach` and are forgotten by the reset,
+ * while spies created during a test are restored afterwards.
+ */
+const testSpies: MockInstance[] = [];
+const persistentSpies = new Set<MockInstance>();
+let firstTest = true;
+const originalSpyOn = vi.spyOn.bind(vi) as (...args: unknown[]) => MockInstance;
+
+vi.spyOn = ((...args: unknown[]) => {
+  const spy = originalSpyOn(...args);
+
+  if (!persistentSpies.has(spy)) {
+    testSpies.push(spy);
+  }
+
+  return spy;
+}) as unknown as typeof vi.spyOn;
+
+beforeEach(() => {
+  if (firstTest) {
+    firstTest = false;
+
+    // Anything already spied before the first test belongs to the file, not the
+    // test. Keep it alive for every test in the file.
+    for (const spy of testSpies) {
+      persistentSpies.add(spy);
+    }
+  }
+
+  testSpies.length = 0;
+});
+
+afterEach(() => {
+  for (const spy of testSpies.splice(0)) {
+    spy.mockRestore();
+  }
+});

src/renderer/hooks/notifications/useNotificationActions.test.tsx

@@ -57,7 +57,6 @@ describe('renderer/hooks/notifications/useNotificationActions.ts', () => {
   beforeEach(() => {
     getAllNotificationsMock.mockReset();
     useAccountsStore.setState({ accounts: [mockGitHubCloudAccount] });
-    mockGitifyNotification.unread = true;
   });
 
   it('exposes the notification actions without fetching or creating a query', () => {

src/renderer/hooks/useNotifications.test.tsx

@@ -93,14 +93,13 @@ describe('renderer/hooks/useNotifications.ts', () => {
     raiseSoundNotificationSpy.mockClear();
     raiseNativeNotificationSpy.mockClear();
     getAllNotificationsMock.mockReset();
+    getAllNotificationsMock.mockResolvedValue([]);
     refreshEnrichmentCacheMock.mockReset();
+    refreshEnrichmentCacheMock.mockReturnValue(false);
     clearServerPollIntervals();
 
     useAccountsStore.setState({ accounts: [mockGitHubCloudAccount] });
     useNotificationActionFailuresStore.getState().reset();
-
-    // Reset mock notification state between tests since it's mutated
-    mockGitifyNotification.unread = true;
   });
 
   describe('fetching notifications', () => {

vitest.config.mts

@@ -18,7 +18,7 @@ export default defineConfig({
   test: {
     globals: true,
     pool: 'vmThreads',
-    isolate: false,
+    isolate: true,
     clearMocks: true,
     unstubEnvs: true,
     unstubGlobals: true,
@@ -56,6 +56,7 @@ export default defineConfig({
           exclude: [...defaultExclude, '**/*.visual.test.tsx'],
           setupFiles: [
             './src/__helpers__/electron-log.setup.ts',
+            './src/__helpers__/restore-test-spies.setup.ts',
             './src/renderer/__helpers__/vitest.setup.ts',
           ],
         },
@@ -67,7 +68,10 @@ export default defineConfig({
           name: 'node [main, shared]',
           environment: 'node',
           include: ['src/shared/**/*.test.{ts,tsx}', 'src/main/**/*.test.{ts,tsx}'],
-          setupFiles: ['./src/__helpers__/electron-log.setup.ts'],
+          setupFiles: [
+            './src/__helpers__/electron-log.setup.ts',
+            './src/__helpers__/restore-test-spies.setup.ts',
+          ],
         },
       },
       {