Deprecates That property and suggest Instance instead

[Evangelink]

This moves will allows to introduce the following fluent Assert.That(x).IsYYY pattern

[cagrin]

I'm not happy with that change. You can already do Assert.That.IsSomething(x, ...) using an extension method on this Assert. To me, it's not a significant improvement — especially when compared to Shouldly.

[Evangelink]

@cagrin your syntax is a little bit different Assert.That.Contains(x, collection) which is equivalent to Assert.Contains(x, collection) vs Assert.That(collection).Contains(x). Moreoever, we have implemented Assert.That(expression) feature in #5991. We have been thinking about a couple of alternatives for the name but this one felt the more natural.

Looking up to GitHub repos using MSTest That, we saw only handful usage so it felt like it would not be too painful to update`.

How many instances does this change impact on your codebase?

[cagrin]

Yes, I agree, the name That will be best for this type of assertion extension. I'm waiting for new methods. I'll try to adapt my extensions to the new Instance name or find another convinient way.

[mdrexel]

Hello, I saw that 3.10.1 had released and went to check the changelog, and I just wanted to chime in that deprecating the .That extension point is very painful... we have tens of thousands of usages via an internal helper library 😢

[orbitalbits]

Seconding what @mdrexel just wrote here. We have tens of thousands of uses of the .That extension point. Deprecating this extension is going to incur a very significant negative impact on us. Please reconsider this change.

[Youssef1313]

Thanks for the feedback @cagrin, @mdrexel, and @orbitalbits. I reverted for now in #6323, and will be experimenting with having both the Assert.That property and Assert.That(() => ...) methods working using extension members coming in C# 14.

[orbitalbits]

@Youssef1313 thank you, we appreciate it.

[Evangelink]

Great call @Youssef1313 and thanks everyone for the feedback! If extension methods aren't working we can go back to a different naming like Assert.Subject, Assert.ThatSubject, Assert.Expression ...

[Youssef1313]

Great call @Youssef1313 and thanks everyone for the feedback! If extension methods aren't working we can go back to a different naming like Assert.Subject, Assert.ThatSubject, Assert.Expression ...

Either a different name, or with "extension members" (C# 14). Hopefully, VB/F# might follow-up and support it as well?