ArgumentParser<_>.PrintCommandLineArgumentsFlat does not escape '\n'

[kleidemos]

Repro steps

module BugInArgu =
  open Expecto
  open Expecto.Flip
  open Argu

  type Args =
    | SomeString of string

    interface IArgParserTemplate with
      member this.Usage =
        match this with
        | SomeString _ -> "NIE"

  let parser =
    ArgumentParser<Args>()

  [<Tests>]
  let tests =
    ftestList "argu" [
      testCase "string contains new line" <| fun () ->
        let str = "\nnewLine\nnewLine\n"
        let args = [
          SomeString str
        ]
        
        args
        |> parser.PrintCommandLineArgumentsFlat
        |> Expect.equal "" (sprintf "--somestring %A" str)
    ]

Actual behavior

[23:40:21 ERR] argu/string contains new line failed in 00:00:00.0420000.
. String does not match at position 13. Expected char: '"', but got '\010'.
expected:
--somestring "
newLine
newLine
"
  actual:
--somestring
newLine
newLine

   at...

[eiriktsarpalis]

I'm not sure I understand what the expected behaviour is. The method prints literal quotes but fails to do so if you add newline chars?

[kleidemos]

PrintCommandLineArgumentsFlat must quote parameters with newline chars, like whitespaces.

[eiriktsarpalis]

PrintCommandLineArgumentsFlat must quote parameters with newline chars, like whitespaces.

Could you elaborate why? Why shouldn't it be quoted if that is not the case?

[kleidemos]

Sorry. But I didn't understand or couldn't translate the question.

• Using %A generates the required string only in this case. I was too lazy to write full implementation.
• We can quote any string, even if it is not necessary. But it doesn't seem good.

[bartelink]

@kleidemos Would you be able to provide a PR? Eirik is no longer maintaining this as of #191

Realistically the fact that this API is not a mainstream thing means resolving this won't get to the top of the up for grabs or good-first-issue lists in any reasonable length of time (I'm trying to make this issues list tractable, as no issue will ever get resolved if its just a dumping ground)