A file can be added to a folder resource using the file picker

1. Log in as teacher, turn editing on and add a folder resource.
2. Click 'Add' and verify that the file picker is launched.
3. Select 'Upload a file', choose a file to upload and upload it.
4. Click 'Save changes' and verify that the file has been uploaded.
5. Log in as a student and download the file, then verify that the file is correct.

Note: It is not necessary to test uploading a very large file. A file of size less than 20MB should be used in this test.