Add configure option to build tests only on request (#940)

Option: ./configure --disable-test   build test programs (default=yes)

Thanks for the patch(es) to @michaelbaeuerle.

I added `make test` to be able to build the test programs from the
FLTK root directory if FLTK was configured with --disable-test.

Makefile

@@ -1,7 +1,7 @@
 #
 # Top-level Makefile for the Fast Light Tool Kit (FLTK).
 #
-# Copyright 1998-2023 by Bill Spitzak and others.
+# Copyright 1998-2024 by Bill Spitzak and others.
 #
 # This library is free software. Distribution and use rights are outlined in
 # the file "COPYING" which should have been included with this file.  If this
@@ -16,7 +16,7 @@
 
 include makeinclude
 
-DIRS = $(IMAGEDIRS) $(LIBDECORDIR) src $(CAIRODIR) $(FLUIDDIR) fltk-options test \
+DIRS = $(IMAGEDIRS) $(LIBDECORDIR) src $(CAIRODIR) $(FLUIDDIR) fltk-options $(TESTDIR) \
        documentation
 
 all: makeinclude fltk-config
@@ -25,6 +25,11 @@ all: makeinclude fltk-config
 		(cd $$dir; $(MAKE) $(MFLAGS)) || exit 1;\
 	done
 
+# Build test programs (and 'all') if FLTK was configured with '--disable-test'
+test: all
+	echo "=== making test ===";\
+	(cd test; $(MAKE) $(MFLAGS)) || exit 1
+
 install: makeinclude
 	-mkdir -p $(DESTDIR)$(bindir)
 	$(RM) $(DESTDIR)$(bindir)/fltk-config

configure.ac

@@ -3,7 +3,7 @@ dnl the "configure" script is made from this by running GNU "autoconf"
 dnl
 dnl Configuration script for the Fast Light Tool Kit (FLTK).
 dnl
-dnl Copyright 1998-2023 by Bill Spitzak and others.
+dnl Copyright 1998-2024 by Bill Spitzak and others.
 dnl
 dnl This library is free software. Distribution and use rights are outlined in
 dnl the file "COPYING" which should have been included with this file.  If this
@@ -102,6 +102,14 @@ AS_IF([test x$enable_debug = xyes], [
     DEBUGFLAG=""
 ])
 
+AC_ARG_ENABLE([test], AS_HELP_STRING([--disable-test], [build test programs (default=yes)]))
+AS_IF([test x$enable_test = xno], [
+    TESTDIR=""
+], [
+    TESTDIR="test"
+])
+AC_SUBST(TESTDIR)
+
 AC_ARG_ENABLE([forms], AS_HELP_STRING([--disable-forms], [build Forms compatibility library (default=yes)]))
 
 AC_ARG_ENABLE([gl], AS_HELP_STRING([--disable-gl], [turn off OpenGL support]))
@@ -1815,6 +1823,12 @@ AS_IF([test x$enable_fluid != xno], [
     echo "    Build fluid: NO"
     ])
 
+AS_IF([test x$enable_test != xno], [
+    echo "    Build tests: YES"
+    ],[
+    echo "    Build tests: NO"
+    ])
+
 AS_IF([test "$fltk_cross_compiling" = "yes"], [
     echo "Cross-compiling: YES"
     echo "          Build: $build -> Host: $host"

makeinclude.in

@@ -89,6 +89,9 @@ GLLIBBASENAME	= @GLLIBBASENAME@
 IMGLIBBASENAME	= @IMGLIBBASENAME@
 CAIROLIBBASENAME= @CAIROLIBBASENAME@
 
+# Test programs (optional, --disable-test):
+TESTDIR		= @TESTDIR@
+
 # libraries to link with:
 AUDIOLIBS	= @AUDIOLIBS@
 CAIROLIBS	= @CAIROLIBS@