Bump CustomBuildTasks to .NET 4.0

[Therzok]

This bumps the build tasks to .NET 4.0 for preliminary support of building libgit2sharp in Mono 4. I still don't know if XUnit 2.0 works on Mono 4, but XUnit 1.9.2 won't work because pre-4.0 profiles were removed.

[Therzok]

Forgot I did this as part of xunit 2.0 port.

[Therzok]

Hey @nulltoken, can we please have this merged it can be built with mono4? Tests don't matter for now.

[bording]

If this does get merged in, I'll be sure to account for this in #984, because I've added a task to CustomBuildTasks there.

CustomBuildTasks is another good candidate for moving out of the main repo and bringing it in via NuGet. We'd be able to stop checking in the dll that way!

[Therzok]

Just a minor notice: All Linux travis CI builds will fail. Mono package is now 4.0, and xunit 1.9.2 uses .NET 2.0 profile, which has been removed.

Not sure if XUnit 2.0 works there, but worth a try, probably.

[nulltoken]

Hmrpf... Well, we've got quite a conundrum here.

As far as I understand it, the current situation is

• Mac OS X runs against Mono 3.6
• Linux runs against latest stable Mono
• Mono 4.0 has been released and current PRs no longer pass on Linux (cf @whoisj's Enable custom unit test location with standard location fallback #1035)
• We know xUnit 1.9.2 won't run with Mono 4.0
• We don't know if xUnit 2.0 will work with Mono 4.0 (Ongoing WIP [WIP] Migrate to Xunit 2.0 #895)

@Therzok@bording@carlosmn I'd really like to keep on supporting Mono 3.6 for some time while still allowing LibGit2Sharp to work with Mono 4.0. If we cannot think of a quick solution, I wonder if the safest short-term solution wouldn't be to pin the Linux builds to Mono 3.12.1 while we try to figure out something... Thoughts?

[nulltoken]

I wonder if the safest short-term solution wouldn't be to pin the Linux builds to Mono 3.12.1 while we try to figure out something..

Eventually did this with #1036

Now we can take a little bit time to think about the dual 3.6/4.0 Mono support

[bording]

Forcing the CI builds to keep away from 4.0 definitely seems like the best course of action for now.

If/when xUnit works with Mono 4.0, I'm guessing that means it's not likely to work with 3.12 or earlier.

If we end up with a with 1.9.2/3.122.0/4.0 split, then that gets pretty messy. The only thing that comes to mind would be having multiple test projects in the repo, one using 1.9.2 and one using 2.0, and share as much of the test code as possible between them. Then with some CI script magic we could build/run the appropriate test project for each platform.

That's even assuming the changes to get the test project working with 2.0 wouldn't completely break 1.9.2 support, which from what I've seen probably isn't a safe assumption.

If that is possible, it's still going to be maintenance nightmare though. 😦

[nulltoken]

Rebased