Copy a non-existent file.
function testNonExistent() {
// Copy non-existent file
$desired_filepath = $this
->randomName();
$this
->assertFalse(file_exists($desired_filepath), "Randomly named file doesn't exists.");
$new_filepath = file_unmanaged_copy($desired_filepath, $this
->randomName());
$this
->assertFalse($new_filepath, 'Copying a missing file fails.');
}