This issue only needs to be tested in 1 device. In the app, login in master site as a student. Go to MM Dev Testing > Resource: File > Sample PDF. Check that you see some info about the file: type, size, created date, modified date. Click open. Check that the file is opened. Go back to the app. Check that now it also says when it was last downloaded. In web as teacher, go to edit that resource. In the file picker, don't delete the existing file. Instead, upload a new file with the same name as the existing one and select "Overwrite" when Moodle tells you there's a file with that name. Save changes. Back in the app, perform a Pull To Refresh. Check that now it displays a warning saying "This file has changed since you last opened it.". Go offline and click "Open". Check that you see a modal saying: "There is a newer version of this file. To see it, please connect your device to the internet.". Click Ok. Check that the file is opened. Now go online and click "Open". Check that the file is opened without the warning modal from step 9. Check that now the app no longer displays the warning "This file has changed since you last opened it.".