feat: refactor tests

Author: vladislavkeblysh

src/courseware/course/sequence/sequence-navigation/UnitButton.test.jsx

@@ -82,4 +82,12 @@ describe('Unit Button', () => {
     fireEvent.click(screen.getByRole('tab'));
     expect(onClick).toHaveBeenCalledTimes(1);
   });
+
+  it('renders with no unitId and does not crash', async () => {
+    render(<UnitButton unitId={undefined} onClick={jest.fn()} contentType="video" title="Unit" />, {
+      wrapWithRouter: true,
+    });
+
+    expect(screen.getByRole('tab')).toBeInTheDocument();
+  });
 });