[`Microsoft.Testing.Platform`] `testconfig.json` should support setting environment variables

[julealgon]

Summary

The new testconfig.json file should allow setting environment variables the same way the old runsettings.xml files did.

Many frameworks and systems rely on environment variables for configuration, and having a mechanism to pass those for the specific test run via the testconfig.json instead of forcing them to be defined globally is ideal.

This also helps bridging the gap with the old runsettings.xml-based mechanism, which did allow for specifying environment variables as part of its spec.

Background and Motivation

We are migrating some of our test projects to the new Microsoft.Test.Platform framework, and as part of that, we want to replace all usages of the runsettings file with the new testconfig.json.

One of the features lacking in testconfig.json currently is being able to define environment variables for the test.

Proposed Feature

A new json section should be supported as part of the testconfig.json schema that allows one to define environment variables. Here is an example:

{
  "environmentVariables": {
    "DOTNET_ENVIRONMENT": "Development",
    "HEADED": "1"
  }
}

Alternative Designs

For now, we created our own custom ITestHostEnvironmentVariableProvider implementation that reads the values from IConfiguration and sets them manually.

We would like to have this as a native feature, so we don't have to maintain that extension.

[Youssef1313]

I don't think we should do it in testconfig.json. This is better served by launchSettings.json which is already established. Today, launchSettings.json is respected as normal when using dotnet run, but not when using dotnet test. With the new dotnet test for MTP in .NET 10, launchSettings.json will be supported.

[julealgon]

@Youssef1313 launchSettings.json is only used for development purposes. It would not be a full replacement.

Having said that, I would 100% agree with making it work properly for test projects regardless.

I think the current situation with test projects is very convoluted with all these variants for doing similar things:

• launchSettings.json
• testconfig.json
• runsettings
• xunit.runner.json (for xUnit)
• appsettings.json (not idiomatic on tests at the moment but absolutely essential for higher-level testing projects)

With the new dotnet test for MTP in .NET 10, launchSettings.json will be supported.

This is great to hear. First time I get a confirmation of this.

I had seen this old item before:

• LaunchSettings are not respected by Test Runner aspnet/Tooling#1089