Re: [Haskell-cafe] Stack & Test Coverage

On Tue, Sep 3, 2019 at 11:14 PM Ben Gamari wrote:

On September 4, 2019 4:32:29 AM GMT+02:00, Hilco Wijbenga wrote:

...

Hi all,

I have a very simple

newtype Index = Index Int deriving (Eq, Ord, Enum)

for which I have written tests with both HSpec and QuickCheck. Specifically, I have written tests for "==", "/=", "compare" (for all of EQ, LT, and GT), and "toEnum" & "fromEnum". So I thought I had _very_ thoroughly covered that one line. :-)

Unfortunately, after running "stack clean ; stack test --coverage" I see in the HTML report that only Eq has been tested and that Ord and Enum have _no_ coverage (i.e. "never executed").

(The module also has some regular functions and an explicit Show instance [all with tests] and those are apparently fine. So coverage does seem to work but not the way I expect?)

What am I doing wrong?

Cheers, Hilco _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.

This sounds like it may be a ghc bug. Can you open a ticket at https://gitlab.haskell.org/ghc/ghc?

Well, I wasn't expecting that. :-) I created a tiny test project with just the newtype and even removed Enum. I tried all LTSs listed at https://www.stackage.org from LST-3.22 all the way up to nightly-2019-09-04 and they all behave the same way. (Stack is _awesome_ for this.) I also tried "data" instead of "newtype". That made no difference. Are you sure this might be a GHC bug? Surely someone would have noticed sometime during the last 4 years? It would have been in GHC 7.10.2 already. Anyway, if "yes" then I'll create an issue. It should be very easy to reproduce. (I don't mean to doubt you but it's rather rare in software that it's "the compiler" and not "the developer". :-) I don't want to waste anyone's time.)