Read global.json to decide to run dotnet test in vstest or testing platform mode

[mariam-abdulla]

General

This is a draft proposal document for designing the global.json file for specifying the test runner with which we will be running the tests in the test projects.

Description

We have been working on improving the user experience in dotnet test by using Microsoft Testing Platform when running tests.
If you are interested in learning about the new testing platform, please check out this link.

We want to allow users to opt-in/opt-out this new experience through a global.json file where you specify the test runner with which you want to run your tests.

Suggestion

Please find below a sample of the global.json file

{
	"test" : {	
		"runner": {
			"name": "MicrosoftTestingPlatform"
		}
	}	
}

OR

{
	"test" : {	
		"runner": {
			"name": "VSTest"
		}
	}	
}

[MarcoRossignoli]

LGTM as starting point, we will keep this in hold till we have the doc approved with the correct names.

[KalleOlaviNiemitalo]

This looks for "test-sdk" but the example in the PR description has "test-sdks".

[Evangelink]

Could you add some tests?

[mariam-abdulla]

Could you add some tests?

I already did, it's in the integration tests PR.
https://github.com/dotnet/sdk/pull/45138/files#diff-45db39b74f3224fc348535ecbff7c7dbf5662f17ff42d63a0303d72f22407298R171

https://github.com/dotnet/sdk/pull/45138/files#diff-45db39b74f3224fc348535ecbff7c7dbf5662f17ff42d63a0303d72f22407298R191

[Evangelink]

Relates to #45927

[marcpopMSFT]

Can you hold off on adding more capabilities into global.json until we've sorted out what we want the path forward to be per #45471. Per the discussion there, global.json may not be the preferred path forward for this and I think we need a partner discussion on this to settle on a direction.

[Evangelink]

@marcpopMSFT could I please be included in the deisgn meetings) you will have? Also, do you have some kind of rough estimate of when you think we would have a solution so we can ensure we are on track for net10 release.