If you’re using @testing-library/react rather than @testing-library/react-native, and you have an alt attribute on your image, you can avoid using getByDataTestId and instead use getByAltText.
it('uses correct src', async () => {
const { getByAltText } = await render(<MyComponent />);
const image = getByAltText('the_alt_text');
expect(image.src).toContain('the_url');
// or
expect(image).toHaveAttribute('src', 'the_url')
});
Documentation.
Unfortunately, it appears that React Native Testing Library does not include getByAltText. (Thank you, @P.Lorand!)