setupTests.ts

import { Image } from 'react-native';
import {
  mockUriGood,
  mockUriBad,
  mockUriSlowGood,
  mockUriSlowBad,
  mockResourceGood,
  mockWidth,
  mockHeight,
} from './src/__fixtures__';

jest.spyOn(Image, 'getSize').mockImplementation((uri, onLoad = () => {}, onError = () => {}) => {
  switch (uri) {
    case mockUriGood: {
      onLoad(mockWidth, mockHeight);
      break;
    }
    case mockUriBad: {
      onError(new Error(uri));
      break;
    }
    case mockUriSlowGood: {
      setImmediate(() => {
        onLoad(mockWidth, mockHeight);
      });
      break;
    }
    case mockUriSlowBad: {
      setImmediate(() => {
        onError(uri);
      });
      break;
    }
    default: {
      throw new Error(`Unexpected URI value in test: ${uri}`);
    }
  }
});

// @ts-expect-error: contrary to what TS thinks, the current implementation of
// resolveAssetSource _can_ return `null`, so this is a valid mock.
jest.spyOn(Image, 'resolveAssetSource').mockImplementation((source) => {
  if (source === mockResourceGood) {
    return { width: mockWidth, height: mockHeight };
  }
  return null;
});