add unit tests

tests/components/Dropdown.test.tsx

@@ -0,0 +1,55 @@
+import { fireEvent, render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+import { Dropdown } from '../../src/components/Dropdown';
+
+const choices = [
+    { id: 'USER', label: 'User' },
+    { id: 'ADMIN', label: 'Admin' },
+];
+
+describe('Dropdown', () => {
+    it('calls onChange with selected value', () => {
+        const onChange = vi.fn();
+        render(<Dropdown label="Role" value="USER" choices={choices} onChange={onChange} />);
+
+        fireEvent.change(screen.getByLabelText('Role'), { target: { value: 'ADMIN' } });
+        expect(onChange).toHaveBeenCalledWith('ADMIN');
+    });
+
+    it('supports inline layout and disabled/required state', () => {
+        const { container } = render(
+            <Dropdown
+                label="Rows"
+                value="10"
+                choices={[{ id: '10', label: '10' }]}
+                layout="inline"
+                disabled
+                required
+            />,
+        );
+
+        const select = screen.getByLabelText('Rows');
+        expect(select).toBeDisabled();
+        expect(select).toBeRequired();
+        expect(container.querySelector('label')).toHaveClass('inline-flex');
+    });
+
+    it('renders error and custom class names', () => {
+        const { container } = render(
+            <Dropdown
+                label="Role"
+                value="USER"
+                choices={choices}
+                error="Role is invalid"
+                className="custom-wrapper"
+                selectClassName="custom-select"
+            />,
+        );
+
+        const select = container.querySelector('select');
+        expect(select).toBeInstanceOf(HTMLSelectElement);
+        expect(screen.getByText('Role is invalid')).toBeInTheDocument();
+        expect(select).toHaveClass('custom-select');
+        expect(screen.getByText('Role').closest('label')).toHaveClass('custom-wrapper');
+    });
+});