build: Add unit test build control through BUILD_TESTING and YSTDLIB_CPP_BUILD_TESTING flags; Support CTest through Catch2 functions.

CMake/ystdlib-cpp-helpers.cmake

@@ -1,8 +1,8 @@
 # Adds a c++20 interface library in the subdirectory NAME with the target NAME and alias
 # NAMESPACE::NAME. Libraries with multiple levels of namespace nesting are currently not supported.
 #
-# If `BUILD_TESTING` is ON, build the unit tests specific to the current library, and link this
-# library against the unified unit test target for the entire `ystdlib-cpp`.
+# If `YSTDLIB_CPP_ENABLE_TESTS` is ON, builds the unit tests specific to the current library, and
+# links this library against the unified unit test target for the entire `ystdlib-cpp` project.
 #
 # @param NAME
 # @param NAMESPACE
@@ -41,7 +41,8 @@ function(cpp_library)
     target_compile_features(${arg_cpp_lib_NAME} INTERFACE cxx_std_20)
     add_library(${arg_cpp_lib_NAMESPACE}::${arg_cpp_lib_NAME} ALIAS ${arg_cpp_lib_NAME})
 
-    if(BUILD_TESTING)
+    if(YSTDLIB_CPP_ENABLE_TESTS)
+        # Build library-specific unit test target
         set(_UNIT_TEST_TARGET "unit-test-${arg_cpp_lib_NAME}")
         add_executable(${_UNIT_TEST_TARGET})
         target_sources(${_UNIT_TEST_TARGET} PRIVATE ${arg_cpp_lib_TESTS_SOURCES})

CMakeLists.txt

@@ -11,12 +11,24 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS
     FORCE
 )
 
-option(BUILD_TESTING "If ON, unit tests will be built." ON)
+if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
+    set(YSTDLIB_CPP_MASTER_PROJECT ON CACHE BOOL "ystdlib-cpp is the top-level CMake project.")
+endif()
+
+# Enable unit test building by default if `BUILD_TESING` is not already defined in the parent scope.
+if(NOT DEFINED BUILD_TESTING)
+    set(BUILD_TESTING ON)
+endif()
+
+set(YSTDLIB_CPP_ENABLE_TESTS OFF)
+if((YSTDLIB_CPP_MASTER_PROJECT OR YSTDLIB_CPP_BUILD_TESTING) AND BUILD_TESTING)
+    set(YSTDLIB_CPP_ENABLE_TESTS ON)
+endif()
 
 # Import CMake helper functions
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/CMake)
 
-if(BUILD_TESTING)
+if(YSTDLIB_CPP_ENABLE_TESTS)
     find_package(Catch2 3.8.0 REQUIRED)
     if(Catch2_FOUND)
         message(STATUS "Found Catch2 ${Catch2_VERSION}.")

README.md

@@ -5,6 +5,7 @@ An open-source C++ library developed and used at YScope.
 # Usage
 Clone `ystdlib-cpp` into your project. Then, in your project's `CMakeLists.txt`, add the following:
 ```cmake
+set(YSTDLIB_CPP_BUILD_TESTING OFF)
 add_subdirectory(/path/to/ystdlib-cpp EXCLUDE_FROM_ALL)
 target_link_libraries(<target_name> <link_options>
     ystdlib::<lib_1> ystdlib::<lib_2> ... ystdlib::<lib_N>