Angular unit test file upload input - DataTransfer is undefined

Trying to write a Jest unit test for a file upload input element.

Based on what i've found online, I'm trying to mock selecting a file by programmatically setting the files attribute on the input element like so:

function selectFile(inputElement: HTMLInputElement) {
const dataTransfer = new DataTransfer();
const mockFile = new File(['Hello World'], 'test-file.txt');
dataTransfer.items.add(mockFile);
inputElement.files = dataTransfer.files;
inputElement.dispatchEvent(new InputEvent('change'));
return fixture.whenStable();
}


However I just receive the error that "DataTransfer is not defined".

Is there something I'm missing here? Why is DataTransfer undefined? Or how else am I supposed to mock selecting a file for a unit test with Jest?

This is the post I found for reference. Here is another post of someone else using Jest and having the same issue. But the incident was closed without any resolution.

Continue reading...