tests: gnss: rtk: Add testsuite to validate RTCM3 protocol

To capture framing capabilities (only API so far).

Signed-off-by: Luis Ubieda <luisf@croxel.com>

Author: ubieda

tests/subsys/gnss/rtk/rtcm3/CMakeLists.txt

@@ -0,0 +1,9 @@
+# Copyright (c) 2025 Croxel Inc.
+# Copyright (c) 2025 CogniPilot Foundation
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(gnss_rtk_decoder_rtcm3_test)
+
+target_sources(app PRIVATE src/main.c)

tests/subsys/gnss/rtk/rtcm3/prj.conf

@@ -0,0 +1,3 @@
+CONFIG_GNSS_RTK=y
+CONFIG_GNSS_RTK_PROTOCOL_RTCM3=y
+CONFIG_ZTEST=y

tests/subsys/gnss/rtk/rtcm3/src/main.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2025 Croxel Inc.
+ * Copyright (c) 2025 CogniPilot Foundation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/ztest.h>
+#include <zephyr/kernel.h>
+
+#include <zephyr/gnss/rtk/decoder.h>
+
+ZTEST_SUITE(rtk_decoder, NULL, NULL, NULL, NULL, NULL);
+
+ZTEST(rtk_decoder, test_frame_is_detected)
+{
+	uint8_t cmd_rtcm3[] = {
+		0xD3, /* Sync byte */
+		0x00, 0x04, /* Length: 4 bytes */
+		0x4C, 0xE0, 0x00, 0x80, /* Payload */
+		0xED, 0xED, 0xD6 /* CRC */
+	};
+	uint8_t *data;
+	size_t data_len;
+
+	zassert_equal(0,
+		      gnss_rtk_decoder_frame_get(cmd_rtcm3, sizeof(cmd_rtcm3), &data, &data_len));
+	zassert_equal_ptr(cmd_rtcm3, data);
+	zassert_equal(sizeof(cmd_rtcm3), data_len);
+}
+
+ZTEST(rtk_decoder, test_frame_is_detected_after_invalid_data)
+{
+	uint8_t cmd_rtcm3[] = {
+		0xFF, 0xFF,
+		0xD3, /* Sync byte */
+		0x00, 0x04, /* Length: 4 bytes */
+		0x4C, 0xE0, 0x00, 0x80, /* Payload */
+		0xED, 0xED, 0xD6 /* CRC */
+	};
+	uint8_t *data;
+	size_t data_len;
+
+	zassert_equal(0,
+		      gnss_rtk_decoder_frame_get(cmd_rtcm3, sizeof(cmd_rtcm3), &data, &data_len));
+	zassert_equal_ptr(&cmd_rtcm3[2], data);
+	zassert_equal(sizeof(cmd_rtcm3) - 2, data_len);
+}
+
+ZTEST(rtk_decoder, test_frame_with_invalid_crc_is_invalid_data)
+{
+	uint8_t cmd_rtcm3[] = {0xD3, 0x00, 0x01, 0xFF, 0x00, 0x01, 0x02};
+	uint8_t *data;
+	size_t data_len;
+
+	zassert_equal(-ENOENT,
+		      gnss_rtk_decoder_frame_get(cmd_rtcm3, sizeof(cmd_rtcm3), &data, &data_len));
+}

tests/subsys/gnss/rtk/rtcm3/testcase.yaml

@@ -0,0 +1,9 @@
+# Copyright (c) 2025 Croxel Inc.
+# Copyright (c) 2025 CogniPilot Foundation
+# SPDX-License-Identifier: Apache-2.0
+
+tests:
+  gnss.rtk.decoder.rtcm3:
+    tags: rtk
+    platform_allow:
+      - native_sim