How to get React Test Renderer instance in React Native Testing Library

Question

I have a component with a lifecycle method added by the navigation library - React Native Navigation (https://wix.github.io/react-native-navigation/#/docs/Usage?id=screen-lifecycle).

I must call this lifecycle method (componentDidAppear) in tests so that my component render correctly.

I was able to call this method on the component instance when I used React Test Renderer. How do I call it with React Native Testing Library? How can I get test renderer instance in RN Testing-Library?

Answer 1

You can get to it via the getByType function:

const subject = render(<SomeComponent />);
subject.getByType(SomeComponent).instance.componentDidAppear()

Note how instance is a property on the interface, not a function (as is the case for some other libraries).