Fix decode_signed32(); Add unit/bacnet/bacint tests (#392)

Fix decode_signed32() length for -8388608 and NULL apdu handling.

Add comprehensive unit tests for bacint.c functionality.

Verified by:

1. (Pass) From $bacnet-stack/test:
            make clean test
2. (Pass) From $workspace (above $bacnet-stack):
            west build -p always -b unit_testing \
              bacnet-stack/zephyr/tests/unit/bacnet/bacint/ && \
            ./build/testbinary

3. (Pass) From $workspace (above $bacnet-stack):
            ./zephyr/scripts/twister -p unit_testing \
              -T bacnet-stack/zephyr/tests/unit/bacnet/bacint/

Signed-off-by: Gregory Shue <gregory.shue@legrand.com>
Co-authored-by: Gregory Shue <gregory.shue@legrand.com>

src/bacnet/bacint.c

@@ -424,7 +424,7 @@ int encode_signed32(uint8_t *apdu, int32_t value)
 
 int decode_signed32(uint8_t *apdu, int32_t *value)
 {
-    if (value) {
+    if (apdu && value) {
         *value = ((int32_t)((((int32_t)apdu[0]) << 24) & 0xff000000));
         *value |= ((int32_t)((((int32_t)apdu[1]) << 16) & 0x00ff0000));
         *value |= ((int32_t)((((int32_t)apdu[2]) << 8) & 0x0000ff00));
@@ -448,7 +448,7 @@ int bacnet_signed_length(int32_t value)
         len = 1;
     } else if ((value >= -32768) && (value < 32768)) {
         len = 2;
-    } else if ((value > -8388608) && (value < 8388608)) {
+    } else if ((value >= -8388608) && (value < 8388608)) {
         len = 3;
     } else {
         len = 4;

test/unit/bacnet/bacint/CMakeLists.txt

@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: MIT
+
+cmake_minimum_required(VERSION 3.10 FATAL_ERROR)
+
+get_filename_component(basename ${CMAKE_CURRENT_SOURCE_DIR} NAME)
+project(test_${basename}
+	VERSION 1.0.0
+	LANGUAGES C)
+
+
+string(REGEX REPLACE
+    "/test/unit/bacnet/[a-zA-Z_/-]*$"
+    "/src"
+    SRC_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR})
+string(REGEX REPLACE
+    "/test/unit/bacnet/[a-zA-Z_/-]*$"
+    "/test"
+    TST_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR})
+set(ZTST_DIR "${TST_DIR}/ztest/src")
+
+add_compile_definitions(
+	BIG_ENDIAN=0
+	CONFIG_ZTEST=1
+	)
+
+include_directories(
+	${SRC_DIR}
+	${TST_DIR}/ztest/include
+	)
+
+add_executable(${PROJECT_NAME}
+    # File(s) under test
+    #   NOTE: bits.h contains the complete implementation of the API.
+    # Support files and stubs (pathname alphabetical)
+    # Test and test library files
+	./src/main.c
+	${ZTST_DIR}/ztest_mock.c
+	${ZTST_DIR}/ztest.c
+	)

zephyr/tests/unit/bacnet/bacint/CMakeLists.txt

@@ -0,0 +1,26 @@
+# Copyright (c) 2022 Legrand North America, LLC.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+if(NOT ZEPHYR_CURRENT_MODULE_DIR)
+  string(REGEX REPLACE "/zephyr/tests/[a-zA-Z_/-]*$" ""
+    ZEPHYR_CURRENT_MODULE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+endif()
+
+set(SOURCES
+  ${ZEPHYR_CURRENT_MODULE_DIR}/test/unit/bacnet/bacint/src/main.c
+  )
+
+project(bacnet_bacint)
+find_package(Zephyr COMPONENTS unittest REQUIRED HINTS $ENV{ZEPHYR_BASE})
+
+# NOTE for Zephyr >= v3.2.0:
+# - Zephyr unittest builds for target 'testbinary' instead of 'app'.
+# - Zephyr unittest does not generate ZEPHYR_<modulename>_MODULE_DIR.
+# So we have to use relative paths to get to the source.
+
+target_include_directories(testbinary PRIVATE
+  ${ZEPHYR_CURRENT_MODULE_DIR}/src
+  )

zephyr/tests/unit/bacnet/bacint/prj.conf

@@ -0,0 +1 @@
+# This file is intentionally empty

zephyr/tests/unit/bacnet/bacint/testcase.yaml

@@ -0,0 +1,3 @@
+tests:
+  bacnet.bacint.unit:
+    type: unit