Unexpected behavior on folders with no projects

[mio-moto]

I was debugging today a problem with our CI environment on my development machine and noticed a strange bug where the Editor was upgrading randomly, not noticing that my terminal went back to my home folder.

PS C:\Users\mio> Start-UnityEditor -Wait -LogFile build.txt -AdditionalArguments " -buildPlatform Desktop -buildOutput $PWD\Build -buildTarget Win64 "  -ExecuteMethod BuildTools.Pipeline.StartCommandLineBuild -Batchmode -WhatIf
What if: Performing the operation "System.Diagnostics.Process.Start()" on target "C:\Program Files\Unity\Hub\Editor\2020.2.1f1\Editor\Unity.exe -executeMethod BuildTools.Pipeline.StartCommandLineBuild -logFile build.txt -batchmode  -buildPlatform Desktop -buildOutput C:\Users\mio\Build -buildTarget Win64 ".

That is no bug per-se, the command line utility selects the latest editor (due to the missing ProjectVersion.txt). However, the editor still executes fine - because Unity does store the last opened project somewhere (I'm guessing either by registry key or somewhere in LocalAppData), and opens that.

Start-UnityEditor falls back to the latest version, starts the Editor, which then opens the last opened project, no matter which ProjectVersion.txt.

Reproduction

Execute Start-UnityEditor in a folder that does not contain a Unity project

Possible Solutions

Start-UnityEditor should either be able to find the folder that Unity is going to open or exit prematurely with an error code that this folder is not a Unity project folder.

[jwittner]

Interesting, when I run Start-UnityEditor from a non-unity project folder I essentially get the Unity Hub to open. It's an interesting bit of confusion, but this working as intended currently. If there's a unity project and you haven't passed -IgnoreProjectContext then it launches the latest version of Unity, which Unity has changed to fall back to the Hub if installed and there's no unity project specified I believe. This gives one a quick way to get into Unity from the command line if you don't have a project available.

What might make sense though is to look at what other arguments have come in to Start-UnityEditor and if they seem like they'd only make sense if a project is discovered/specified, then throw the error?

[jwittner]

Retitled as there really is no 'incorrect version' on projects without a folder.

[mio-moto]

If I had to guesstimate, then Unity is not opening the hub either because of -batchmode, since it already assumes that there is no UI involved. Probably good guess that -nographics does something similar (but I have yet to test that either).

I think your additions generally make sense, it's not actively hurting (our) CI process, it's most a side-effect I have discovered while working on our CIs

[mister-liss]

I have seen another variant of this issue recently. In our CI, when we open Unity with the intent to license it, Unity is consistently emitting a new empty project into the WorkingDirectory. I could not replicate this on my local machine. Locally, I saw what the above users mentioned, either Unity opened a cached project or if there was no cached project, the hub would open. I circumvented the issue by explicitly using the "-CreateProject" flag to create a decoy project in the build machine's Temp folder when licensing.