While testing with a domain test account, I discovered an interesting issue/bug/feature with Office and SharePoint integration.
Using the domain account with “Restricted Reader” permissions, I navigated to a SharePoint Document Library and clicked the document icon to open in Word.
Word launched as expected with the yellow “You must checkout this document” warning/dialog. Seems normal and in fact it is, however clicking the “Check out” button as a restricted reader should NOT allow you to check the document out. It did. Initially this seems like a bug, but after some trial, error and thought; it’s not.
Issue: I logged onto the SharePoint site as the test user, however I’m logged into the MACHINE as DOMAIN\Username. Word thinks of us as who we are logged into the machine as, NOT who we’re logged into SharePoint as.
Resolution: To accurately test things like this, it is highly recommended to log onto the machine with the test account that you intend to use. This will prevent issues like this, and your test will be more accurate.