I inject dependency in test by anther trick

  [TestFixture]
  public class SshToolClientTests
  {
      private ServiceProvider serviceProvider { get; set; }
      private ISshToolClient client=> serviceProvider.GetService<ISshToolClient>();

      public SshToolClientTests() {
          serviceProvider = new ServiceCollection()
         .AddTransient<ISshToolClient, SshToolClient.SshToolClient>()
         .BuildServiceProvider();

      }


      [OneTimeTearDown]
      public void OneTimeTeardown()
      {
          serviceProvider.Dispose();
      }
      [SetUp]
      public void Setup()
      {
      }

      [Test]
      public void GenerateConfigFile( )
      {
          ISshConfig config= client.GetDefaultConfiguration();
          Assert.IsNotNull(config);
          var json=JsonConvert.SerializeObject(config, Formatting.Indented);
          string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "generatedSshConfig.json");
          File.WriteAllText(path, json);
          TestContext.WriteLine(@$"file:///{path.Replace('\\','/')}");
      }
  }