How to use user secrets in a dotnet core test project

See instructions in https://patrickhuber.github.io/2017/07/26/avoid-secrets-in-dot-net-core-tests.html, in particular in InitialiseTest add

// the type specified here is just so the secrets library can 
// find the UserSecretId we added in the csproj file
var builder = new ConfigurationBuilder().AddUserSecrets<HttpClientTests>();
    
Configuration = builder.Build()

However note that it will not allow to run tests on build server