Allow DotNetHostPath to contain env vars

[Therzok]

This is useful for controlling the paths to the dotnet host path when you're running dotnet test src/tests/TestProjectA.csproj to avoid duplicating the runsettings.

[Therzok]

Tests are failing because SelectSingleNode is likely case sensitive?

[Evangelink]

No test is failing on CI. Is there any change you would have forgot to push?

[Therzok]

Check previous CI runs, the problem was with the casing. If I used <RunConfiguration><DotnetHostPath> instead of DotNetHostPath it would break.

[Evangelink]

Thanks! We are planning on improving the way we read/write values in runsettings so I guess this could be handled here.

[nohwnd]

Thanks for the PR. Please add a test that uses the new feature, so we don't lose it later.

[Evangelink]

@Therzok Could you add some tests (as mentioned by @nohwnd)?

[Therzok]

Yes, sorry, I completely forgot about the PR :D

[Evangelink]

No worries and thanks for the remaining work.

[Therzok]

I've modified an existing test to handle this scenario.

[Evangelink]

LGTM! @nohwnd For a second review.

[nohwnd]

Probably an edge case, but would you expect environment variables that are defined in the runsettings (or from commandline via -e) to be also usable and expandable here?

[Therzok]

Didn't even know that's possible. I just followed the logic that applied to ResultsDirectory, and made it also work on DotNetHostPath :D

The way I wanted to integrate it is via msbuild setting the environment variable (some common props file) from a test project, so it could support different nesting inside a solution directory layout.

<!-- this is imported via some shared props -->
<DotNetHostPath>build/bin/App</DotNetHostPath>

src
- Implementation
- - Implementation.Tests
- Tests

Currently, with the relative path, if you use the solution as an argument to dotnet test it works, but when you pass in a project, it breaks, as it tries to probe into directories relative to the project.

[nohwnd]

Let's leave that suggestion for later then.

Thanks for the PR, merged.