Add a test-install target to the Makefile

This target will be used to check if an installation
of Janet is on the PATH, if native modules can be built
and used via the cook module, etc.

Makefile

@@ -239,6 +239,9 @@ install: $(JANET_TARGET)
 	mkdir -p $(MANPATH)
 	cp janet.1 $(MANPATH)
 
+test-install:
+	cd test/install && janet test
+
 uninstall:
 	-rm $(BINDIR)/../$(JANET_TARGET)
 	-rm -rf $(INCLUDEDIR)

examples/numarray/.gitignore

@@ -0,0 +1 @@
+/build

test/install/.gitignore

@@ -0,0 +1 @@
+/build

test/install/test.janet

@@ -0,0 +1,11 @@
+(import cook)
+
+(cook/make-native
+    :name "testmod"
+    :source @["testmod.c"])
+
+(import build/testmod :as testmod)
+
+(if (not= 5 (testmod/get5)) (error "testmod/get5 failed"))
+
+(print "OK!")

test/install/testmod.c

@@ -0,0 +1,40 @@
+/*
+* Copyright (c) 2019 Calvin Rose and contributors
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to
+* deal in the Software without restriction, including without limitation the
+* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+* sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+* IN THE SOFTWARE.
+*/
+
+/* A very simple native module */
+
+#include <janet.h>
+
+static Janet cfun_get_five(int32_t argc, Janet *argv) {
+    (void) argv;
+    janet_fixarity(argc, 0);
+    return janet_wrap_number(5.0);
+}
+
+static const JanetReg array_cfuns[] = {
+    {"get5", cfun_get_five, NULL},
+    {NULL, NULL, NULL}
+};
+
+JANET_MODULE_ENTRY(JanetTable *env) {
+    janet_cfuns(env, NULL, array_cfuns);
+}