• via Digitalmars-d-bugs (38/39) Jul 01 2014 https://issues.dlang.org/show_bug.cgi?id=13014

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=13014

          Issue ID: 13014
           Summary: Test Phobos with a QuickCheck-like tool too?
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: Phobos
          Assignee: nobody puremagic.com
          Reporter: bearophile_hugs eml.cc

QuickCheck is a testing tool widely used in Haskell:

http://www.haskell.org/haskellwiki/Introduction_to_QuickCheck1
http://en.wikipedia.org/wiki/QuickCheck

In QuickCheck the programmer writes assertions about logical properties that a
function should fulfill. Then QuickCheck attempts to generate test cases that
falsify these assertions.<

The test cases are generated randomly, up to a certain length and complexity,
that can be specified.

In Haskell there is also a similar tool, SmallCheck, that "allows to verify
properties for all test cases up to some depth", so its test cases are not
random, it's deterministic:
http://ro-che.info/articles/2013-02-19-smallcheck.html
https://github.com/feuerbach/smallcheck


There are QuickCheck-like tools for most languages, including D and C++:
https://github.com/mcandre/dashcheck
http://software.legiasoft.com/quickcheck/

In this enhancement request I suggest to consider using a QuickCheck-like tool
(like DashCheck) to test Phobos, and to better remove Phobos bugs. The
functions that specify the logical proprieties of the Phobos code should be
bundled inside the standard D distributions, like the unittests.

One side effect of shipping the D compiler with a QuickCheck-like tool (used
for Phobos, and later for the front-end written in D) is to encourage D
programmers to use such standard tool in their programs. I think this could
improve the quality of all D code, beyond Phobos.

Note: such testing functions are similar to the post-conditions. So in theory a
well implemented QuickCheck-like tool for D should use the post-conditions to
generate the test cases.

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