tests: add snippet test suite

Add an initial test suite for the basic SNIPPET_ROOT, SNIPPET, and
'append' features in snippet.yml.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

tests/cmake/snippets/CMakeLists.txt

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+set(SNIPPET_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/extra_snippet_root")
+set(SNIPPET foo bar)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(test_snippets)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

tests/cmake/snippets/Kconfig

@@ -0,0 +1,14 @@
+# Copyright 2023 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+mainmenu "Snippet tests"
+
+menu "Zephyr"
+source "Kconfig.zephyr"
+endmenu
+
+config FOO
+	int "Helper option for testing snippet foo"
+	default 1
+	help
+	  This option's value should be overridden by the foo snippet.

tests/cmake/snippets/app.overlay

@@ -0,0 +1,4 @@
+/ {
+	/* This node will be deleted by the bar snippet. */
+	deleted-by-bar {};
+};

tests/cmake/snippets/extra_snippet_root/snippets/bar/bar.overlay

@@ -0,0 +1,3 @@
+/ {
+	/delete-node/ deleted-by-bar;
+};

tests/cmake/snippets/extra_snippet_root/snippets/bar/snippet.yml

@@ -0,0 +1,3 @@
+name: bar
+append:
+  DTC_OVERLAY_FILE: bar.overlay

tests/cmake/snippets/prj.conf

@@ -0,0 +1,2 @@
+CONFIG_ZTEST=y
+CONFIG_ZTEST_NEW_API=y

tests/cmake/snippets/snippets/foo/foo.conf

@@ -0,0 +1 @@
+CONFIG_FOO=2

tests/cmake/snippets/snippets/foo/snippet.yml

@@ -0,0 +1,3 @@
+name: foo
+append:
+  OVERLAY_CONFIG: foo.conf

tests/cmake/snippets/src/main.c

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/ztest.h>
+#include <zephyr/devicetree.h>
+
+ZTEST_SUITE(snippet_tests, NULL, NULL, NULL, NULL, NULL);
+
+ZTEST(snippet_tests, test_foo)
+{
+	zassert_equal(CONFIG_FOO, 2, "foo snippet should set CONFIG_FOO=2");
+}
+
+ZTEST(snippet_tests, test_bar)
+{
+	zassert_equal(DT_NODE_EXISTS(DT_PATH(deleted_by_bar)), 0,
+		      "bar snippet should delete /deleted-by-bar node");
+}

tests/cmake/snippets/testcase.yaml

@@ -0,0 +1,6 @@
+tests:
+  cmake.snippets:
+    tags: snippets
+    platform_allow: native_posix qemu_x86 qemu_x86_64 qemu_cortex_m3
+    integration_platforms:
+      - native_posix