What version of avast are you using? Avast Internet Security? It looks like the virus is in the sandbox. Close your browser and delete all temporary internet files. If you are using AIS go to the Avast GUI/additional protection/sandbox/webbrowsers and under maintenance delete the contents.
Good. It would probably be a good idea if you went ahead and performed a Malwarebytes scan. I would still question if it were completely gone just by closing your browser, cleaning out temporary internet files and deleting test.exe. If it is completely gone then the autosandbox did what it is designed to do. Also delete any restore points, if any, that were created today. Since it was run in the sandbox did you have an autosandbox popup appear and if you did, what actions did you apply? In the autosandbox settings do you have it set to ask or auto?