Build gtest from source by adding its subdirectory

Disable warnings for the gtest library target

CMakeLists.txt

@@ -297,25 +297,22 @@ if(CPPDAP_BUILD_TESTS)
 
     if(CPPDAP_USE_EXTERNAL_GTEST_PACKAGE)
         find_package(GTest REQUIRED)
+        set(CPPDAP_GTEST_TARGET GTest::gtest)
     else()
-        list(APPEND DAP_TEST_LIST
-            ${CPPDAP_GOOGLETEST_DIR}/googletest/src/gtest-all.cc
-        )
-	set_property(SOURCE
-            ${CPPDAP_GOOGLETEST_DIR}/googletest/src/gtest-all.cc
-            APPEND PROPERTY COMPILE_OPTIONS -w)
-
-        set(DAP_TEST_INCLUDE_DIR
-            ${CPPDAP_GOOGLETEST_DIR}/googlemock/include/
-            ${CPPDAP_GOOGLETEST_DIR}/googletest/
-            ${CPPDAP_GOOGLETEST_DIR}/googletest/include/
-        )
+        # Build gtest from source
+        set(INSTALL_GTEST OFF)
+        add_subdirectory(${CPPDAP_GOOGLETEST_DIR}/googlemock)
+        # googletest has -Werror=maybe-uninitialized problem.
+        # Disable all warnings in googletest code.
+        target_compile_options(gtest PRIVATE -w)
+        set(CPPDAP_GTEST_TARGET gtest)
+        set(DAP_TEST_INCLUDE_DIR ${CPPDAP_GOOGLETEST_DIR}/googlemock/include/)
     endif()
 
     add_executable(cppdap-unittests ${DAP_TEST_LIST})
     add_test(NAME cppdap-unittests COMMAND cppdap-unittests)
 
-    target_include_directories(cppdap-unittests PUBLIC ${DAP_TEST_INCLUDE_DIR} )
+    target_include_directories(cppdap-unittests PUBLIC ${DAP_TEST_INCLUDE_DIR})
     set_target_properties(cppdap-unittests PROPERTIES
         FOLDER "Tests"
     )
@@ -326,11 +323,7 @@ if(CPPDAP_BUILD_TESTS)
     endif()
 
     cppdap_set_target_options(cppdap-unittests)
-    if(CPPDAP_USE_EXTERNAL_GTEST_PACKAGE)
-        target_link_libraries(cppdap-unittests PRIVATE cppdap GTest::gtest)
-    else()
-        target_link_libraries(cppdap-unittests PRIVATE cppdap)
-    endif()
+    target_link_libraries(cppdap-unittests PRIVATE cppdap ${CPPDAP_GTEST_TARGET})
 endif(CPPDAP_BUILD_TESTS)
 
 # fuzzer