Paket should communicate why it is re-running dependency resolution

[mavnn]

Description

There are situations where Paket will check for new versions of dependencies during paket install even though paket.dependencies and paket.lock are unchanged. A common example is when you have a dependency with only prerelease versions available (but not marked as prerelease) - paket will check every time to see if a release version has become available.

This is fine, but currently paket does not tell you why it is checking; this can be frustrating with large projects which suddenly become very slow to work with.

Repro steps

Install a package with only prerelease versions available. Do not mark it prerelease in paket.dependencies.

Run paket install again - paket will go and hit nuget.org with no apparent reason.

Expected behavior

Paket should display a message explaining what has happened, e.g.:

Running resolver for group Main since package MyPackage is a prerelease version;
specify an exact version or "prerelease" in paket.dependencies if you do not which to check for updates.

Actual behavior

The resolver runs, every time

Known workarounds

@forki tells you about this behaviour on Twitter 😛

[TeaDrivenDev]

I've started looking at this as a "practice" issue, as it's neither entirely trivial nor requires a super deep understanding of everything.

The interesting part seems to be around https://github.com/fsprojects/Paket/blob/master/src/Paket.Core/Installation/UpdateProcess.fs#L98.

One question is how specific we'd want to be with the reasons shown for triggering the resolver. The issue title and the text don't seem to describe exactly the same thing here. Is this just about the very specific thing described above because it can be difficult to detect, or are there other reasons too that should be shown?

[mavnn]

Sorry, yeah. The title text is meaningless, I have changed it!

I wrote this in a bit of a hurry to capture what had happened and my frustration at it - and to see if it would be possible to spare other people the frustration!

In my personal opinion, I'd be very happy if paket always displayed the reason why it was going off to check packages. The only ones I'm aware of are:

• packages aren't there
• dependency/lock file changed
• we locked a prerelease version of a package that isn't marked prerelease in paket.dependencies, so we go to check if there's now a release

I wasn't aware of that last one, and it caused me some pain :). There might be others, but if there are I don't know what they are - and I doubt most other users do either!