Tiny Makefile template for c++

Makefile

# define variable, use using $()
# -g add debug information to the executable file
# -Wall turns on most, but not all, compiler warnings
# using Emacs and M-x replace-string RET string RET newstring RET 
# to replace xx to your file name.
# Use google's testing framework
GTEST_DIR = ../gtest

# Where to find user code.
USER_DIR = ../gtest_sample

# Flags to passed to the preprocessor
CPPFLAGS += -I$(GTEST_DIR)/include

CXX_FLAGS += -g -Wall -Wextra

TESTS = sample_test

# All Google test headers.
GTEST_HEADERS = $(GTEST_DIR)/include/gtest/*.h \
		$(GTEST_DIR)/include/gtest/internal/*.h

all : $(TESTS)

clean : 
	rm -f $(TESTS) gtest.a gtest_main.a *.o

# Builds gtest.a gtest_main.a
GTEST_SRCS_ = $(GTEST_DIR)/src/*.cc $(GTEST_DIR)/src/*.h $(GTEST_HEADERS)

gtest-all.o : $(GTEST_SRCS_)
	$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) -c \
	    $(GTEST_DIR)/src/gtest-all.cc

gtest_main.o : $(GTEST_SRCS_)
	$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) -c \
	    $(GTEST_DIR)/src/gtest_main.cc

gtest.a : gtest-all.o
	$(AR) $(ARFLAGS) $@ $^

gtest_main.a : gtest-all.o gtest_main.o
	$(AR) $(ARFLAGS) $@ $^

sample.o : $(USER_DIR)/sample.cc $(USER_DIR)/sample.h $(GTEST_HEADERS)
	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $(USER_DIR)/sample.cc

sample_test.o : $(USER_DIR)/sample_test.cc \
		$(USER_DIR)/sample.h $(GTEST_HEADERS)
	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $(USER_DIR)/sample_test.cc

sample_test : sample.o sample_test.o gtest_main.a
	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -lpthread $^ -o $@