Clarify the need for QuickCheck/Haskell tests

Expands the devnotes.rst doc and adds warnings in the Makefile.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

Makefile.am

@@ -447,6 +447,10 @@ endif
 
 $(HS_ALL_PROGS): %: %.hs $(HS_LIB_SRCS) $(HS_BUILT_SRCS) Makefile
 	BINARY=$(@:htools/%=%); \
+	if [ "$$BINARY" = "test" ] && [ -z "$(GHC_PKG_QUICKCHECK)" ]; then \
+	  echo "Error: cannot run unittests without the QuickCheck library (see devnotes.rst)" 1>&2; \
+	  exit 1; \
+	fi; \
 	$(GHC) --make \
 	  $(HFLAGS) $(HEXTRA) $(HTOOLS_NOCURL) \
 	  -osuf $$BINARY.o -hisuf $$BINARY.hi \

configure.ac

@@ -369,6 +369,9 @@ else
   AC_MSG_CHECKING([network])
   GHC_PKG_NETWORK=$($GHC_PKG latest network)
   AC_MSG_RESULT($GHC_PKG_NETWORK)
+  AC_MSG_CHECKING([QuickCheck 1.x])
+  GHC_PKG_QUICKCHECK=$($GHC_PKG --simple-output list 'QuickCheck-1.*')
+  AC_MSG_RESULT($GHC_PKG_QUICKCHECK)
   if test -z "$GHC_PKG_PARALLEL" || test -z "$GHC_PKG_JSON" || \
      test -z "$GHC_PKG_NETWORK"; then
     if test "$enable_htools" != "check"; then
@@ -379,8 +382,13 @@ else
     # we leave the other modules to be auto-selected
     HTOOLS_MODULES="-package $GHC_PKG_PARALLEL"
   fi
+  if test -z "$GHC_PKG_QUICKCHECK"; then
+     AC_MSG_WARN(m4_normalize([The QuickCheck 1.x module was not found,
+                               you won't be able to run Haskell unittests]))
+  fi
 fi
 AC_SUBST(HTOOLS_MODULES)
+AC_SUBST(GHC_PKG_QUICKCHECK)
 
 if test "$enable_htools" != "no"; then
   if test -z "$GHC" || test -z "$HTOOLS_MODULES"; then

doc/devnotes.rst

@@ -38,7 +38,13 @@ document, plus:
   linter (equivalent to pylint for Python)
 - the `QuickCheck <http://hackage.haskell.org/package/QuickCheck>`_
   library, version 1.x
-- ``hpc``, which comes with the compiler, so you should already have it
+- ``hpc``, which comes with the compiler, so you should already have
+  it
+
+Under Debian, these can be installed (on top of the required ones from
+the quick install document) via::
+
+  apt-get install libghc6-quickcheck1-dev hscolour hlint
 
 
 Configuring for development