test(UnifiedFontStore): add isEmpty and destroy tests

src/entities/Font/model/store/unifiedFontStore/unifiedFontStore.test.ts

@@ -433,3 +433,58 @@ describe('category getters', () => {
         expect(store.monospaceFonts.every(f => f.category === 'monospace')).toBe(true);
     });
 });
+
+describe('isEmpty', () => {
+    let store: UnifiedFontStore;
+
+    beforeEach(() => {
+        store = new UnifiedFontStore({ limit: 10 });
+    });
+
+    afterEach(() => {
+        store.destroy();
+        queryClient.clear();
+        vi.resetAllMocks();
+    });
+
+    it('is true when fetch returns no fonts', async () => {
+        mockedFetch.mockResolvedValue(makeResponse([]));
+        await store.refetch();
+
+        expect(store.isEmpty).toBe(true);
+    });
+
+    it('is false when fonts are present', async () => {
+        mockedFetch.mockResolvedValue(makeResponse(generateMockFonts(3)));
+        await store.refetch();
+
+        expect(store.isEmpty).toBe(false);
+    });
+
+    it('is true after an error (no fonts loaded)', async () => {
+        mockedFetch.mockRejectedValue(new Error('network down'));
+        await store.refetch().catch((e: unknown) => e);
+
+        expect(store.isEmpty).toBe(true);
+    });
+});
+
+describe('destroy', () => {
+    it('can be called without throwing', () => {
+        const store = new UnifiedFontStore({ limit: 10 });
+
+        expect(() => {
+            store.destroy();
+        }).not.toThrow();
+    });
+
+    it('sets filterCleanup to null so it is not called again', () => {
+        const store = new UnifiedFontStore({ limit: 10 });
+        store.destroy();
+
+        // Second destroy should not throw even though filterCleanup is now null
+        expect(() => {
+            store.destroy();
+        }).not.toThrow();
+    });
+});