anchor.diff:              ignoreMissing = true,
               ignoreUnrecognized = true,
               raiseOnUsage = false)
  -        let isList = parsed.Contains <@ ListTests @>
  +        let isList = parsed.Contains <@ List_Tests @>
           (baseConfig, parsed.GetAllResults()) ||> Seq.fold (flip reduceKnown), isList
   
  +  /// Prints out names of all tests for given test suite.
     let listTests test =
       test
       |> Test.toTestCodeList
       |> Seq.iter (fst3 >> printfn "%s")
  -
  -    0
   
     /// Runs tests with supplied options. Returns 0 if all tests passed, =
     /// otherwise 1
  
positive.code:     | Parallel
      | Debug
      | Filter of hiera:string
      | FilterTestList of substring:string
      | FilterTestCase of substring:string
      | ListTests
  
      interface IArgParserTemplate with
        member s.Usage =
  
negative.code:         | Parallel -> fun o -> { o with parallel = true }
          | Debug -> fun o -> { o with verbosity = LogLevel.Debug }
          | Filter _ -> fun o -> failwith "TODO: PRs much appreciated."
          | Filter_Test_List _ -> fun o -> failwith "TODO: PRs much appreciated."
          | Filter_Test_Case _ -> fun o -> failwith "TODO: PRs much appreciated."
          | List_Tests -> id
  
  
  
  