Mocking file input in React TestUtils

Do you need a 'true' file? I think your issue is in how you're managing your 'fake' file, and your file input's change event. You can use the File Api to 'create' a dummy file, and then you just have to properly set your file input. It doesn't use value, but rather files.

// similar example from KCD https://github.com/testing-library/react-testing-library/issues/93#issuecomment-392126991const file = new File(['(⌐□_□)'], 'chucknorris.png', { type: 'image/png' });TestUtils.Simulate.change(fileInput, { target: { files: [ file ] } });

If you actually needed the 'file' (upload_text.txt), then that could be more tricky. Node fs.readFile is async, and the data isn't available outside of the callback, plus you'd have to convert the data into an actual file object to give to the input.

// rough pass at this, you'll have to play with itimport fs from 'fs';const filename = 'upload_text.txt';fs.readFile(filename, 'utf8', (err, data) => {  if (err) throw err;  const file = new File(data, filename, { type: 'text/plain' });  TestUtils.Simulate.change(fileInput, { target: { files: [ file ] } });  // whatever comes next});