Fix for apple clang build issue for GTest

cmake/FindGTestSrc.cmake

@@ -1,26 +1,27 @@
-
 SET(GTEST_SEARCH_PATH
-    "${GTEST_SOURCE_DIR}"
-    "${CMAKE_CURRENT_LIST_DIR}/../thirdparty/googletest/googletest")
+        "${CMAKE_CURRENT_LIST_DIR}/../thirdparty/googletest/googletest"
+        "${GTEST_SOURCE_DIR}"
+)
 
 IF(UNIX)
     LIST(APPEND GTEST_SEARCH_PATH "/usr/src/gtest")
 ENDIF()
 
 FIND_PATH(GTEST_SOURCE_DIR
-    NAMES CMakeLists.txt src/gtest_main.cc
-    PATHS ${GTEST_SEARCH_PATH})
-
+        NAMES CMakeLists.txt src/gtest_main.cc
+        PATHS ${GTEST_SEARCH_PATH}
+        NO_DEFAULT_PATH)
 
 # Debian installs gtest include directory in /usr/include, thus need to look
 # for include directory separately from source directory.
 FIND_PATH(GTEST_INCLUDE_DIR
-    NAMES gtest/gtest.h
-    PATH_SUFFIXES include
-    HINTS ${GTEST_SOURCE_DIR}
-    PATHS ${GTEST_SEARCH_PATH})
+        NAMES gtest/gtest.h
+        PATH_SUFFIXES include
+        HINTS ${GTEST_SOURCE_DIR}
+        PATHS ${GTEST_SEARCH_PATH}
+        NO_DEFAULT_PATH)
 
 INCLUDE(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(GTestSrc DEFAULT_MSG
-    GTEST_SOURCE_DIR
-    GTEST_INCLUDE_DIR)
+        GTEST_SOURCE_DIR
+        GTEST_INCLUDE_DIR)

test/unittest/CMakeLists.txt

@@ -2,7 +2,9 @@ project(${OASVALIDATOR}-unittests LANGUAGES CXX)
 
 set(GOOGLETEST_VERSION 1.14.0)
 
-find_package(GTestSrc)
+# Include the custom FindGTestSrc.cmake script
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../../cmake")
+find_package(GTestSrc REQUIRED)
 
 IF (GTESTSRC_FOUND)
     enable_testing()
@@ -17,7 +19,6 @@ IF (GTESTSRC_FOUND)
 
     set(TEST_LIBRARIES gtest gtest_main)
 
-
     file(GLOB_RECURSE SOURCES "src/*.cpp")
 
     find_program(CCACHE_FOUND ccache)
@@ -29,7 +30,6 @@ IF (GTESTSRC_FOUND)
         endif ()
     endif (CCACHE_FOUND)
 
-
     add_executable(${PROJECT_NAME} ${SOURCES})
 
     target_include_directories(${PROJECT_NAME}