message: mock out readStats in upload process
diff: import * as fs from 'fs-extra';
  import progressStream from 'progress-stream';
  -import * as readStatsFile from './read-stats-file';
  import { getDependentStoryFiles as dependentStoryFiles } from '../lib/getDependentStoryFiles';
  import { validateFiles, traceChangedFiles, uploadStorybook } from './upload';
  jest.mock('fs-extra');
  jest.mock('progress-stream');
  jest.mock('../lib/getDependentStoryFiles');
  +jest.mock('./read-stats-file');
  const getDependentStoryFiles = <jest.MockedFunction<typeof dependentStoryFiles>>dependentStoryFiles;
  const createReadStream = <jest.MockedFunction<typeof fs.createReadStream>>fs.createReadStream;
  @@ -91,8 +91,6 @@ describe('validateFiles', () => {
  });
  describe('traceChangedFiles', () => {
  - jest.spyOn(readStatsFile, 'readStatsFile').mockReturnValueOnce(Promise.resolve(undefined));
  -
  it('sets onlyStoryFiles on context', async () => {
  const deps = { 123: ['./example.stories.js'] };
  getDependentStoryFiles.mockResolvedValueOnce(deps);
  