From 85bbc2e1dda4ca21efd3b1ec253ca3c5deaec38f Mon Sep 17 00:00:00 2001
From: Alex Selimov <alex@alexselimov.com>
Date: Wed, 16 Apr 2025 07:55:10 -0400
Subject: [PATCH] Guard testing code to avoid problems when including using
 FetchContent.MakeAvailable

---
 CMakeLists.txt | 47 +++++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a62fd7c..d2bebc5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,6 @@ cmake_minimum_required(VERSION 3.9)
 set(NAME "Vec3")
 project(${NAME})
 
-enable_testing()
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 add_compile_options(-Wall -Wextra -Wpedantic)
@@ -11,28 +10,32 @@ set(CMAKE_CXX_STANDARD 17)
 
 include_directories(include)
 add_subdirectory(include)
-add_subdirectory(tests)
 
-# Doxygen Build
-option(BUILD_DOC "Build Documentation" ON)
+if (PROJECT_IS_TOP_LEVEL)
+    enable_testing()
+    add_subdirectory(tests)
 
-find_package(Doxygen)
-if(DOXYGEN_FOUND)
-    set(BUILD_DOC_DIR ${CMAKE_SOURCE_DIR}/build/docs)
-    if(NOT EXISTS ${BUILD_DOC_DIR})
-        file(MAKE_DIRECTORY ${BUILD_DOC_DIR})
-    endif()
+    # Doxygen Build
+    option(BUILD_DOC "Build Documentation" ON)
 
-    set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/docs/Doxyfile)
-    set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
-    configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
+    find_package(Doxygen)
+    if(DOXYGEN_FOUND)
+        set(BUILD_DOC_DIR ${CMAKE_SOURCE_DIR}/build/docs)
+        if(NOT EXISTS ${BUILD_DOC_DIR})
+            file(MAKE_DIRECTORY ${BUILD_DOC_DIR})
+        endif()
 
-    message("Doxygen buld started")
-    add_custom_target(Doxygen_${NAME} ALL
-            COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
-            WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
-            COMMENT "Generating API documentation with Doxygen"
-            VERBATIM)
-else(DOXYGEN_FOUND)
-    message("Doxygen needs to be installed to generate the documentation.")
-endif(DOXYGEN_FOUND)
+        set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/docs/Doxyfile)
+        set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
+        configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
+
+        message("Doxygen buld started")
+        add_custom_target(Doxygen_${NAME} ALL
+                COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
+                WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+                COMMENT "Generating API documentation with Doxygen"
+                VERBATIM)
+    else(DOXYGEN_FOUND)
+        message("Doxygen needs to be installed to generate the documentation.")
+    endif(DOXYGEN_FOUND)
+endif()