I think this is a bug, but it could be a naive user error 
I have a dashboard that was created by copying a file in to /var/lib/grafana/dashboards
These ‘dashboards from file’ don’t have a Save icon - I guess the live dashboard always reflects the file on disk. So the save process I have been using is to make changes, export to json, fiddle with the json a little (remove __inputs and hard code the datasource values), and copy the file back in
So far so good. But I tried the ‘Test Rule’ against a reconfigured Alert and got a pop-up saying ‘The dashboard needs to be saved at least once before you can test an alert rule’
So I exported it and copied the exported file back in as a differently named file and dashboard name, but Test Rule gives the same error.
I have tried a few variations on (matching and different) * (filenames and dashboard titles) but all fail the same way.
Am I missing something or is this a bug?