Use target gtest instead of GTEST_LIB and GTEST_INCLUDE_DIR

This simplifies usage of GoogleTest, since independent handling of
GTEST_LIB and GTEST_INCLUDE_DIR is not necessary anymore.

Additionally CMake creates a dependency now between target gtest and all
test applications using it. This improves build process when building
GoogleTest from source code. When any test application is built,
GoogleTest library is automatically rebuilt if necessary now for
instance.

common/cmake_modules/GncAddTest.cmake

@@ -139,13 +139,9 @@ function(gnc_gtest_configure)
       "${GTEST_SRC_DIR}/src/gtest_main.cc"
       "${GTEST_SRC_DIR}/src/gtest-all.cc"
       PARENT_SCOPE)
-    set(GTEST_LIB "${CMAKE_BINARY_DIR}/common/test-core/libgtest.a" PARENT_SCOPE)
   else()
     find_library(GTEST_SHARED_LIB gtest)
     find_library(GTEST_MAIN_LIB gtest_main)
-    if (GTEST_MAIN_LIB AND GTEST_SHARED_LIB)
-      set(GTEST_LIB "${GTEST_MAIN_LIB};${GTEST_SHARED_LIB}" PARENT_SCOPE)
-    endif()
   endif()
   if ((GTEST_SHARED_LIB OR GTEST_SRC_DIR) AND GTEST_INCLUDE_DIR)
     set(THREADS_PREFER_PTHREAD_FLAG ON)

common/test-core/CMakeLists.txt

@@ -82,6 +82,13 @@ if (GTEST_SRC_DIR)
     target_compile_options(gtest PRIVATE -Wno-missing-declarations)
   endif()
   target_include_directories(gtest PUBLIC ${GTEST_INCLUDE_DIR} ${GTEST_SRC_DIR})
+else()
+  add_library(gtest UNKNOWN IMPORTED GLOBAL)
+  set_target_properties(gtest PROPERTIES
+    IMPORTED_LOCATION ${GTEST_SHARED_LIB}
+    INTERFACE_INCLUDE_DIRECTORIES ${GTEST_INCLUDE_DIR}
+    INTERFACE_LINK_LIBRARIES ${GTEST_MAIN_LIB}
+  )
 endif()
 if (GMOCK_SRC_DIR)
   set (lib_gmock_SOURCES ${GMOCK_SRC})

gnucash/import-export/csv-imp/test/CMakeLists.txt

@@ -12,11 +12,10 @@ set(CSV_IMP_TEST_LIBS gncmod-csv-import gncmod-engine test-core)
 # This test does not run in Win32
 if (NOT WIN32)
   set(MODULEPATH ${CMAKE_SOURCE_DIR}/gnucash/import-export/csv-imp)
-  set(gtest_csv_imp_LIBS gncmod-csv-import ${GLIB2_LDFLAGS} ${GTEST_LIB})
+  set(gtest_csv_imp_LIBS gncmod-csv-import ${GLIB2_LDFLAGS} gtest)
   set(gtest_csv_imp_INCLUDES
     ${MODULEPATH}
-    ${CSV_IMP_TEST_INCLUDE_DIRS}
-    ${GTEST_INCLUDE_DIR})
+    ${CSV_IMP_TEST_INCLUDE_DIRS})
 
   set(test_tokenizer_SOURCES
     test-tokenizer.cpp)

libgnucash/core-utils/test/CMakeLists.txt

@@ -33,14 +33,13 @@ set(gtest_core_utils_INCLUDES
   ${CMAKE_SOURCE_DIR}/common # for platform.h
   ${CMAKE_BINARY_DIR}/libgnucash/core-utils # for gncla-dir.h
   ${GLIB2_INCLUDE_DIRS}
-  ${GTEST_INCLUDE_DIR}
   )
 
 set(gtest_core_utils_LIBS
   ${GLIB2_LDFLAGS}
   ${Boost_LIBRARIES}
   ${GTHREAD_LDFLAGS}
-  ${GTEST_LIB})
+  gtest)
 
 set(test_gnc_path_util_SOURCES
   ${MODULEPATH}/gnc-path.c

libgnucash/engine/test/CMakeLists.txt

@@ -92,7 +92,7 @@ set(gtest_old_engine_LIBS
   gncmod-engine
   ${GLIB2_LDFLAGS}
   ${Boost_LIBRARIES}
-  ${GTEST_LIB})
+  gtest)
 
 set(gtest_qof_LIBS
   ${GLIB2_LDFLAGS}
@@ -101,7 +101,7 @@ set(gtest_qof_LIBS
   ${GTHREAD_LDFLAGS}
   ${ICU4C_I18N_LDFLAGS}
   ${Boost_LIBRARIES}
-  ${GTEST_LIB})
+  gtest)
 
 set(gtest_engine_INCLUDES
   ${MODULEPATH}
@@ -109,7 +109,6 @@ set(gtest_engine_INCLUDES
   ${CMAKE_BINARY_DIR}/common # for config.h
   ${CMAKE_SOURCE_DIR}/common # for platform.h
   ${GLIB2_INCLUDE_DIRS}
-  ${GTEST_INCLUDE_DIR}
   ../../../borrowed/libc
 )