Project Makefile problems with Google Test - makefile

Question

For the life of me I cannot figure out how to remove the mv statements in the following makefile
TEST_DIR = ../gtest
USER_DIR = src
TESTS_DIR = tests
OBJ_DIR = obj
CPPFLAGS += -isystem $(GTEST_DIR)/include -I$(USER_DIR)
CXXFLAGS += -g -Wall -Wextra
TESTS = test
GTEST_HEADERS = $(GTEST_DIR)/include/gtest/*.h \
$(GTEST_DIR)/include/gtest/internal/*.h
all : $(TESTS)
clean :
rm -rf obj
rm -rf bin
mkdir obj
mkdir bin
GTEST_SRCS_ = $(GTEST_DIR)/src/*.cc $(GTEST_DIR)/src/*.h $(GTEST_HEADERS)
$(OBJ_DIR)/gtest-all.o : $(GTEST_SRCS_)
$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) -c \
$(GTEST_DIR)/src/gtest-all.cc
mv gtest-all.o obj/gtest-all.o
$(OBJ_DIR)/gtest_main.o : $(GTEST_SRCS_)
$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) -c \
$(GTEST_DIR)/src/gtest_main.cc
mv gtest_main.o obj/gtest_main.o
$(OBJ_DIR)/gtest.a : $(OBJ_DIR)/gtest-all.o
$(AR) $(ARFLAGS) $# $^
$(OBJ_DIR)/gtest_main.a : $(OBJ_DIR)/gtest-all.o $(OBJ_DIR)/gtest_main.o
$(AR) $(ARFLAGS) $# $^
$(OBJ_DIR)/addition.o : $(USER_DIR)/addition.cpp $(USER_DIR)/addition.h $(GTEST_HEADERS)
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $<
mv addition.o obj/addition.o
$(OBJ_DIR)/test.o : $(TESTS_DIR)/test.cpp $(USER_DIR)/addition.h $(GTEST_HEADERS)
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $(TESTS_DIR)/test.cpp
mv test.o obj/test.o
test : $(OBJ_DIR)/addition.o $(OBJ_DIR)/test.o $(OBJ_DIR)/gtest_main.a
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -lpthread $^ -o $#
The problem is the mv test.o obj/test.o line and the others like it. I know there is a way to have make do this automatically for you but for the life of me I cannot find/figure it out.
This is the precanned makefile that comes with google test that I have modified to work for me.

Answer 1

Something like
CPPFLAGS += -MMD -MP
gtest_objs := $(OBJ_DIR)/gtest_all.o $(OBJ_DIR)/gtest_main.o
my_objs := $(OBJ_DIR)/addition.o $(OBJ_DIR)/test.o
all_objs := $(gtest_objs) $(objs)
deps := $(all_objs:.o=.d)
$(gtest_objs): CPPFLAGS += -I$(GTEST_DIR)
$(gtest_objs): $(OBJ_DIR)/gtest_%.o: $(GTEST_DIR)/src/gtest_%.cc
$(my_objs): $(OBJ_DIR)/%.o: $(USER_DIR)/%.cpp
$(all_objs):
$(COMPILE.cpp) $(OUTPUT_OPTION) $<
-include $(deps)
The rule for all_objs is copied from the builtin rule, and the deps-related stuff will generate dependencies for you automatically.