buildsystem: test for EXTERNAL_PKG_DIRS feature

tests/external_pkg_dirs/Makefile

@@ -0,0 +1,6 @@
+include ../Makefile.tests_common
+
+EXTERNAL_PKG_DIRS += external_pkgs
+USEPKG += external_pkg
+
+include $(RIOTBASE)/Makefile.include

tests/external_pkg_dirs/README.md

@@ -0,0 +1,16 @@
+external_pkg_dirs
+=================
+
+Test application for the EXTERNAL_PKG_DIRS feature of the buildsystem.
+Two external packages are provided in `external_pkgs/`: `external_pkg` and
+`external_pkg_not_used`. If the first package is not properly included, a define
+from `CFLAGS` is missing and a precompiler error is triggered. If the second
+package somehow ends up included it triggers a makefile error.
+
+Usage
+=====
+
+Set `EXTERNAL_PKG_DIRS` inside Makefile to point to other paths where the
+buildsystem can look for packages. Similar functionality to `EXTERNAL_PKG_DIRS`.
+Be careful to not name these externally provided packages the same as existing
+packages in `$(RIOTBASE)/pkg/`.

tests/external_pkg_dirs/external_pkgs/external_pkg/Kconfig

@@ -0,0 +1,9 @@
+# Copyright (c) 2022 Niklaus Leuenberger
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+config PACKAGE_EXTERNAL_PKG
+    bool "external_pkg package"
+    depends on TEST_KCONFIG

tests/external_pkg_dirs/external_pkgs/external_pkg/Makefile

@@ -0,0 +1,16 @@
+PKG_NAME = external_pkg
+
+include $(RIOTBASE)/Makefile.base
+
+.PHONY: all prepare clean distclean
+
+all: prepare
+
+prepare:
+	@:
+
+clean::
+	rm -rf $(BINDIR)/pkg/$(PKG_NAME)
+
+distclean::
+	rm -rf $(BINDIR)/pkg/$(PKG_NAME)

tests/external_pkg_dirs/external_pkgs/external_pkg/Makefile.include

@@ -0,0 +1 @@
+CFLAGS += -DTEST_EXTERNAL_PKG

tests/external_pkg_dirs/external_pkgs/external_pkg_not_used/Kconfig

@@ -0,0 +1,9 @@
+# Copyright (c) 2022 Niklaus Leuenberger
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+config PACKAGE_EXTERNAL_PKG_NOT_USED
+    bool "external_pkg_not_used package"
+    depends on TEST_KCONFIG

tests/external_pkg_dirs/external_pkgs/external_pkg_not_used/Makefile

@@ -0,0 +1,19 @@
+PKG_NAME = external_pkg_not_used
+
+include $(RIOTBASE)/Makefile.base
+
+.PHONY: all prepare clean distclean
+
+all:
+	$(error target all for external_pkg_not_used executed)
+
+prepare:
+	$(error target prepare for external_pkg_not_used executed)
+
+clean::
+	rm -rf $(BINDIR)/pkg/$(PKG_NAME)
+	$(error target clean for external_pkg_not_used executed)
+
+distclean::
+	rm -rf $(BINDIR)/pkg/$(PKG_NAME)
+	$(error target distclean for external_pkg_not_used executed)

tests/external_pkg_dirs/external_pkgs/external_pkg_not_used/Makefile.include

@@ -0,0 +1 @@
+CFLAGS += -DTEST_EXTERNAL_PKG_NOT_USED

tests/external_pkg_dirs/main.c

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2021 Niklaus Leuenberger
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       This is a test for the EXTERNAL_PKG_DIRS variable.
+ *
+ * @author      Niklaus Leuenberger <niklaus.leuenb@gmail.com>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+
+#ifndef TEST_EXTERNAL_PKG
+    #error "Required external package not included."
+#endif
+
+#ifdef TEST_EXTERNAL_PKG_NOT_USED
+    #error "External package included that shouldn't be."
+#endif
+
+int main(void)
+{
+    puts("If it compiles, it works!");
+    return 0;
+}