add unit tests

tests/hooks/useSubmitState.test.tsx

@@ -0,0 +1,44 @@
+import { act } from 'react';
+import { describe, expect, it } from 'vitest';
+import { useSubmitState } from '../../src/hooks/useSubmitState';
+import { renderHook } from '../helpers/renderHook';
+
+describe('useSubmitState', () => {
+    it('tracks submit lifecycle and feedback state', () => {
+        const { result } = renderHook(() => useSubmitState<string | null>(null));
+
+        expect(result.current.isSubmitting).toBe(false);
+        expect(result.current.submitError).toBeNull();
+        expect(result.current.status).toBeNull();
+
+        act(() => {
+            result.current.startSubmitting();
+            result.current.setSubmitError('Oops');
+            result.current.setStatus('Done');
+        });
+
+        expect(result.current.isSubmitting).toBe(true);
+        expect(result.current.submitError).toBe('Oops');
+        expect(result.current.status).toBe('Done');
+
+        act(() => {
+            result.current.finishSubmitting();
+            result.current.clearFeedback();
+        });
+
+        expect(result.current.isSubmitting).toBe(false);
+        expect(result.current.submitError).toBeNull();
+        expect(result.current.status).toBeNull();
+    });
+
+    it('restores the typed initial status in clearFeedback', () => {
+        const { result } = renderHook(() => useSubmitState<'idle' | 'done'>('idle'));
+
+        act(() => {
+            result.current.setStatus('done');
+            result.current.clearFeedback();
+        });
+
+        expect(result.current.status).toBe('idle');
+    });
+});