Re: [Caml-list] Use of unit testing frameworks in OCaml

[Gerd Stolpmann <info@gerd-stolpmann.de>]

[-- Attachment #1: Type: text/plain, Size: 2187 bytes --]

Am Mittwoch, den 09.09.2015, 14:35 -0600 schrieb John Christopher
McAlpine:
>  From what I can tell, the tests for the OCaml compiler and standard 
> libraries are all done with a fairly small framework designed 
> specifically for testing the compiler and standard libraries. Is there 
> any particular reason not to use a tool such as OUnit or Broken for 
> these tests? I am aware that adding dependencies to the compiler is 
> generally frowned upon, but these libraries could significantly improve 
> the maintainability of the core language and libraries.

The last sentence is a quite strong thesis. Recently, I was in a similar
situation as the OCaml developers, namely the need arose to create unit
tests for a fairly large project (a commercial one, so I cannot point to
it). I was considering oUnit. Finally, I dropped it, because it is not
that useful at all.

The point is that the most important function for unit-testing is
polymorphic equality, and this is a built-in. All the other stuff is
absolutely optional, and if you need it, just a matter of 10-20 lines
(e.g. for selecting unit tests from the command-line - IF this is the
applicable environment). It turns out the most useful are utility
functions like

let ( &&& ) x y = x && y
  (* logical AND without short-circuit eval *)

or

let named_check name p =
  if not p then printf "[FAILED: %s]" name;
  p

which are typically missing in unit testing frameworks because these
were once ported from imperative languages. E.g. a test could now look
like

let test0001() =
  named_check "subexpr1" (f 3 4 5 = 8)
  &&& named_check "subexpr2" (g 6 7 8 = 9)

My experience is that all the other stuff you need is highly special to
the project.

What is the gain of maintainability you get by using a framework?

Gerd
-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
------------------------------------------------------------

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 473 bytes --]