input-file-hidden-open-dialog-on-click.html

<!DOCTYPE html>
<html>
<head>
    <meta charset='utf-8' />
    <title>Test that file dialog opens when click() is called </title>
</head>
<body>
Test manually that when you click on "Click me" button, an file open dialog appears.
<input id=fileinput type="file" hidden />
<button onclick="document.getElementById('fileinput').click();">Click me</button>
</body>
</html>

chromium/third_party/blink/manual_tests/input-file-hidden-open-dialog-on-click.html