User should able to troubleshoot the testplatform/adapter failures from logs

[smadala]

Description

See https://github.com/Microsoft/vstest/issues/623#issuecomment-348532950

• User should able to troubleshoot the testplatform/adapter failures from logs obtained by --diag argument.

• Create document to understand critical steps from logs like Is testhost/datacollector launched? Right runsetttings used? Required adapter/extensions loaded? Is communication between process established? etc.. And should figure out that issue related to Clients(VS IDE/VSTest task/dotnet test...), Test platform(vstest), Adapters(MSTestv2/xUnit/Nunit..) or Tests itself.

[soeron]

Even better in test output tab in the IDE.

[smadala]

@soeron Logs can gets very huge based on number of tests(can cause VS hang) and generated in two or more processes( can impact performance).

[soeron]

That's why you can choose what information you want to see there. Obviously if you are looking at the logs most of the time you are trying to figure out where is the problem if there is any, but that's my opinion.

[Evangelink]

This troubleshooting document is a good starting point: https://github.com/microsoft/vstest-docs/blob/main/docs/troubleshooting.md