Visual Studio fails to run some tests about testing

[FabGeek]

Dougbu,
I know its a old post, but for others benefit we had the same issue for some tests. Closing Visual Studio and re-opening it followed with rebuild and re-running all tests resolved the issue.

[dougbu]

/cc @rynowak

[Eilon]

This has been fixed.

[hanslai]

Still having the same problem with Visual Studio 2017 Version 15.4.3.

Close and restart Visual Studio and test run fine again.

[aadhoc]

[ Probable answer included below !! ]

Also having problem with Visual Studio 2017 Version 15.4.5.
After Clean/Build, Output window contains:

[1/16/2018 10:03:57 AM Informational] ========== Discover test finished: 34 found (0:00:04.9669993) ==========
[1/16/2018 10:05:24 AM Informational] ------ Run test started ------
[1/16/2018 10:05:25 AM Informational] [xUnit.net 00:00:00.4034143]   Discovering: ApplicationCoreTest
[1/16/2018 10:05:25 AM Informational] [xUnit.net 00:00:00.4828386]   Discovered:  ApplicationCoreTest
[1/16/2018 10:05:25 AM Informational] [xUnit.net 00:00:00.5216601]   Starting:    ApplicationCoreTest
[1/16/2018 10:05:25 AM Informational] [xUnit.net 00:00:00.7406277]   Finished:    ApplicationCoreTest
[1/16/2018 10:05:25 AM Error] Test adapter sent back a result for an unknown test case. Ignoring result for 'ApplicationCoreTest.ClientGroups.Domain.ValidateClientCreationTests.Validates_WhenTheNameIsMissing_ReturnsError'.
[1/16/2018 10:05:25 AM Error] Test adapter sent back a result for an unknown test case. Ignoring result for 'ApplicationCoreTest.ClientGroups.Domain.ValidateClientCreationTests.Validates_WhenTheNameIsValid_ReturnsNoErrors'.

Just noticed that I have these nuget dependencies:
ApplicationCoreTest:
xunit (2.3.0)
xunit.runner.visualstudio (2.2.0)

WebApiTest:
xunit (2.2.0)
xunit.runner.visualstudio (2.2.0)

.... and the project with the xunit (2.2.0) works, while the xunit (2.3.0) doesn't. Also might be a mismatch with the runner (both are 2.2.0). I just changed that failing one to be xunit (2.2.0) and the problem seems to have gone away. Not sure if this is the permanent solution, but it makes sense that it could be.

[StingyJack]

For the silent skipping of tests, see microsoft/testfx#241 and microsoft/testfx#499

The "Test adapter sent back a result for an unknown test case" (that it executed!), I'll probably log an issue for that later as it shows for every test when I "Run All".