Thanks Ian. I think the matter of using HUnit or QuickCheck is not the most relevant here. The real question his how to test a single function from GHC sources (assuming that it is exported by module in which it is defined)? So let's say there is a module in GHC I want to test: module Foo where foo x y = x + y And I want to write tests for it in the testsuite: module FooTests where import Foo main = ASSERT (foo 2 2 == 4) ASSERT (foo 0 1 == 1) and so on (Hunit would only be a convenient interface here). The question is how can I import a GHC module from within the testsuite and call its functions to test it they behave propertly? An attempt to simply import the module results in compilation error: Failed to load interface for ‛Foo’ It is a member of the hidden package ‛ghc-7.7.20130731’. Use -v to see a list of the files searched for. Is there a workaround for this? Janek ----- Oryginalna wiadomość ----- Od: "Ian Lynagh" Do: "Jan Stolarek" DW: "ghc-devs" Wysłane: środa, 31 lipiec 2013 13:31:44 Temat: Re: Unit-testing of GHC code On Tue, Jul 30, 2013 at 05:28:12PM +0200, Jan Stolarek wrote:

I spent whole day looking for a bug that lurks somewhere in my code, but I know I could find it in 2-3 hours if I only could write unit tests for my code. So the question is: how can I write HUnit and QuickCheck (and maybe SmallCheck) tests for GHC and possibly make them a part of testsuite?

It's better not to use HUnit/QuickCheck/SmallCheck, as then you can add them to the testsuite and they can be run by everyone, without needing the libraries to be installed. Thanks Ian -- Ian Lynagh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

Thank you Ian - this indeed does the trick. But going a bit further I've encountered another problem. I need to run my computations in the Ghc session, because otherwise some actions fail with panic: CmmCopyPropagationTest: CmmCopyPropagationTest: panic! (the 'impossible' happened) (GHC version 7.7.20130731 for i386-unknown-linux): v_unsafeGlobalDynFlags: not initialised My understanding is that I can use runGhc function from Ghc module to run actions in Ghc monad and lift the result to IO monad. I'm having problems with the second paramter to runGhc function. Is there a robust way of obtaining that parameter so that the test is portable across machines (I want to make that test a part of the testsuite)? Janek ----- Oryginalna wiadomość ----- Od: "Ian Lynagh" Do: "Jan Stolarek" DW: "ghc-devs" Wysłane: środa, 31 lipiec 2013 20:07:42 Temat: Re: Unit-testing of GHC code On Wed, Jul 31, 2013 at 04:10:46PM +0200, Jan Stolarek wrote:

and so on (Hunit would only be a convenient interface here). The question is how can I import a GHC module from within the testsuite and call its functions to test it they behave propertly? An attempt to simply import the module results in compilation error:

Failed to load interface for ‛Foo’ It is a member of the hidden package ‛ghc-7.7.20130731’. Use -v to see a list of the files searched for.

Is there a workaround for this?

You need to use "-package ghc" if you want to use the GHC API. Thanks Ian -- Ian Lynagh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/