Add 2e2 tests and restructure the CMake project

.github/workflows/main.yml

@@ -28,7 +28,7 @@ jobs:
           -DCMAKE_BUILD_TYPE=Debug
           -DCMAKE_C_COMPILER=${{ matrix.c-compiler }}
           -DCMAKE_CXX_COMPILER=${{ matrix.cxx-compiler }}
-          tests
+          .
       # language=bash
       - run: |
           cd ${{ github.workspace }}/build
@@ -72,7 +72,7 @@ jobs:
           -DCMAKE_CXX_COMPILER=${{ matrix.cxx-compiler }}
           -DCMAKE_CXX_FLAGS="${{ matrix.cxx-flags }}"
           -DNO_STATIC_ANALYSIS=1
-          tests
+          .
       # language=bash
       - run: |
           cd ${{ github.workspace }}/build

CMakeLists.txt

@@ -0,0 +1,29 @@
+# This software is distributed under the terms of the MIT License.
+# Copyright (C) OpenCyphal Development Team  <opencyphal.org>
+# Copyright Amazon.com Inc. or its affiliates.
+# SPDX-License-Identifier: MIT
+# Author: Pavel Kirienko <pavel@opencyphal.org>
+#
+# This file is only needed for library development and testing. It is not needed to use the library in your project;
+# instead, users should integrate the library by copying its source files.
+
+cmake_minimum_required(VERSION 3.20)
+
+project(udpard)
+enable_testing()
+
+# Shared Clang-Format target for all subprojects.
+find_program(clang_format NAMES clang-format)
+if (NOT clang_format)
+    message(STATUS "Could not locate clang-format")
+else ()
+    file(GLOB_RECURSE format_files
+            ${CMAKE_CURRENT_SOURCE_DIR}/demo/*.[ch]
+            ${CMAKE_CURRENT_SOURCE_DIR}/libudpard/*.[ch]
+            ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.[ch]
+            ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.[ch]pp)
+    message(STATUS "Using clang-format: ${clang_format}; files: ${format_files}")
+    add_custom_target(format COMMAND ${clang_format} -i -fallback-style=none -style=file --verbose ${format_files})
+endif ()
+
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/tests)

libudpard/udpard.h

@@ -390,11 +390,11 @@ struct UdpardMemoryResource
 /// datagrams ready for transmission are not enqueued into the local prioritized queue but instead are sent directly
 /// to the network interface driver using a dedicated callback. The callback would accept not just a single
 /// chunk of data but a list of three chunks to avoid copying the source transfer payload: the datagram header,
-/// the payload, and (only for the last frame) the CRC. The driver would then use some form of vectorized IO to
-/// transmit the data; the advantage of this approach is that up to two data copy operations are eliminated from the
-/// stack and the memory allocator is not used at all. The disadvantage is that if the driver callback is blocking,
-/// the application thread will be blocked as well; plus the driver will be responsible for the correct prioritization
-/// of the outgoing datagrams according to the DSCP value.
+/// the payload, and (only for the last frame) the CRC. The driver would then use some form of vectorized IO or
+/// MSG_MORE/UDP_CORK to transmit the data; the advantage of this approach is that up to two data copy operations are
+/// eliminated from the stack and the memory allocator is not used at all. The disadvantage is that if the driver
+/// callback is blocking, the application thread will be blocked as well; plus the driver will be responsible
+/// for the correct prioritization of the outgoing datagrams according to the DSCP value.
 struct UdpardTx
 {
     /// Pointer to the node-ID of the local node, which is used to populate the source node-ID field of outgoing
@@ -523,6 +523,14 @@ int_fast8_t udpardTxInit(struct UdpardTx* const            self,
 /// The library itself, however, does not use or check this value in any way, so it can be zero if not needed
 /// (this is not recommended for real-time systems).
 ///
+/// Note that due to the priority ordering, transient transfer loss may occur if the user increases the priority
+/// level on a given port. This is because the frames of the new transfer will be enqueued before the frames of
+/// the previous transfer, so the frames of the previous transfer will be transmitted only after the frames of
+/// the new transfer are transmitted, causing the receiver to discard them as duplicates due to their lower transfer-ID.
+/// To avoid this, it is necessary to wait for all frames originating from the port to be delivered before increasing
+/// the priority level on the port. The "user_transfer_reference" may help here as it allows the user to establish
+/// traceability from enqueued transfer frames (datagrams) back to the port they originate from.
+///
 /// The function returns the number of UDP datagrams enqueued, which is always a positive number, in case of success.
 /// In case of failure, the function returns a negated error code.
 ///

tests/.clang-tidy

@@ -1,6 +1,7 @@
 ---
 # The tests are held to somewhat lower quality standards than production code.
 # The tests are also written in somewhat non-idiomatic C++ because they are tightly related to the C codebase.
+InheritParentConfig: true
 Checks: >-
   boost-*,
   bugprone-*,

tests/CMakeLists.txt

@@ -1,5 +1,7 @@
 # This software is distributed under the terms of the MIT License.
-# Copyright (c) OpenCyphal.
+# Copyright (C) OpenCyphal Development Team  <opencyphal.org>
+# Copyright Amazon.com Inc. or its affiliates.
+# SPDX-License-Identifier: MIT
 # Author: Pavel Kirienko <pavel@opencyphal.org>
 
 cmake_minimum_required(VERSION 3.12)
@@ -14,8 +16,8 @@ enable_testing()
 set(CTEST_OUTPUT_ON_FAILURE ON)
 set(NO_STATIC_ANALYSIS OFF CACHE BOOL "disable udpard static analysis")
 
-set(library_dir "${CMAKE_SOURCE_DIR}/../libudpard")
-set(unity_root "${CMAKE_CURRENT_SOURCE_DIR}/../submodules/unity")
+set(library_dir "${CMAKE_SOURCE_DIR}/libudpard")
+set(unity_root "${CMAKE_SOURCE_DIR}/submodules/unity")
 
 # Use -DNO_STATIC_ANALYSIS=1 to suppress static analysis.
 # If not suppressed, the tools used here shall be available, otherwise the build will fail.
@@ -28,19 +30,6 @@ if (NOT NO_STATIC_ANALYSIS)
     message(STATUS "Using clang-tidy: ${clang_tidy}")
 endif ()
 
-# clang-format
-find_program(clang_format NAMES clang-format)
-if (NOT clang_format)
-    message(STATUS "Could not locate clang-format")
-else ()
-    file(GLOB_RECURSE format_files
-            ${library_dir}/*.[ch]
-            ${CMAKE_SOURCE_DIR}/src/*.[ch]
-            ${CMAKE_SOURCE_DIR}/src/*.[ch]pp)
-    message(STATUS "Using clang-format: ${clang_format}; files: ${format_files}")
-    add_custom_target(format COMMAND ${clang_format} -i -fallback-style=none -style=file --verbose ${format_files})
-endif ()
-
 function(gen_test name files compile_definitions compile_flags link_flags c_standard)
     # Unity
     add_library("${name}_unity" STATIC "${unity_root}/src/unity.c")