tests: nrf_modem_lib: Add test for modem trace flash backend

Add tests for the modem trace flash backend.

Signed-off-by: Jan Tore Guggedal <[email protected]>

Author: jtguggedal

tests/lib/nrf_modem_lib/trace_backends/flash/CMakeLists.txt

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+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(flash)
+
+target_include_directories(app PRIVATE src)
+
+# Add test sources
+target_sources(app PRIVATE src/main.c)
+
+# Provide compile-time definitions for configs expected by the backend
+target_compile_definitions(app PRIVATE
+        CONFIG_NRF_MODEM_LIB_TRACE_FLASH_SECTORS=16
+        CONFIG_NRF_MODEM_LIB_TRACE_BACKEND_FLASH_BUF_SIZE=1024
+        CONFIG_NRF_MODEM_LIB_TRACE_BACKEND_FLASH_PARTITION_SIZE=0x10000
+)
+
+# Generate runner for the test
+test_runner_generate(src/main.c)
+
+# Add the actual flash backend implementation
+target_sources(app PRIVATE
+  ${ZEPHYR_NRF_MODULE_DIR}/lib/nrf_modem_lib/trace_backends/flash/flash.c)

tests/lib/nrf_modem_lib/trace_backends/flash/boards/native_sim.overlay

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+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		/* Keep boot and slot0 so chosen code-partition remains valid */
+		/delete-node/ slot1_partition;
+		/delete-node/ scratch_partition;
+		/delete-node/ storage_partition;
+
+		/* modem_trace partition - matches flash backend without partition manager */
+		modem_trace: partition@75000 {
+			label = "modem_trace";
+			reg = <0x00075000 0x00010000>; /* 64KB */
+		};
+	};
+};

tests/lib/nrf_modem_lib/trace_backends/flash/prj.conf

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+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_UNITY=y
+CONFIG_ASSERT=y
+
+# Enable real flash simulator and subsystems
+CONFIG_FLASH=y
+CONFIG_FLASH_MAP=y
+CONFIG_FLASH_SIMULATOR=y
+CONFIG_FLASH_SIMULATOR_UNALIGNED_READ=y
+CONFIG_FLASH_SIMULATOR_EXPLICIT_ERASE=y
+CONFIG_FCB=y
+CONFIG_FCB_ALLOW_FIXED_ENDMARKER=y