一年后我的全新答案，请看这里：The "easy" way: install gtest's headers and .a static library files system-wide into /usr/local/include and /usr/local/lib , respectively

“硬”方法：直接使用g++，out 构建系统，从头开始手动构建所有内容

我终于想通了！关键的参考资料是这一篇，里面有一些我研究过的优秀的构建命令示例来弄清楚这一切：https://ethz-adrl.github.io/ct/ct_core/doc/html/md__home_adrl_code_src_control-toolbox_ct_core_build_test_googletest-src_googletest_README.html
步骤如下：
在Linux Ubuntu上测试。
我首先在我的eRCaGuy_hello_world repo主C++自述文件中记录了这整个过程以及更多内容，如下所示：cpp/README.md .

1.将所有gtest和gmock构建为静态库归档*.a文件

# Clone the repo
git clone https://github.com/google/googletest.git

# Build all of gtest and gmock as static library archive `*.a` files

time g++ -Wall -Wextra -Werror -O3 -std=c++17 -pthread -c \
    -I"googletest/googletest/include" -I"googletest/googletest" \
    -I"googletest/googlemock/include" -I"googletest/googlemock" \
    googletest/googletest/src/gtest-all.cc \
    googletest/googletest/src/gtest_main.cc \
    googletest/googlemock/src/gmock-all.cc \
    googletest/googlemock/src/gmock_main.cc

# move all of the object files just created to a "bin" dir
mkdir -p bin
mv -t bin gtest-all.o gtest_main.o gmock-all.o gmock_main.o

# Use the `ar` "archive" utility to create the *.a static library archive files
# from the 4 object files above
time ar -rv bin/libgtest.a bin/gtest-all.o
time ar -rv bin/libgtest_main.a bin/gtest_main.o
time ar -rv bin/libgmock.a bin/gmock-all.o
time ar -rv bin/libgmock_main.a bin/gmock_main.o

您现在拥有：

bin/libgtest.a
bin/libgtest_main.a
bin/libgmock.a
bin/libgmock_main.a

2.构建并运行googletest附带的一些示例

请在此处查看这些示例测试：https://github.com/google/googletest/tree/main/googletest/samples .
1.对于googletest/googletest/samples/sample1_unittest.cc：

time ( \
    time g++ -Wall -Wextra -Werror -O3 -std=c++17 -pthread \
    -I"googletest/googletest/include" -I"googletest/googlemock/include" \
    googletest/googletest/samples/sample1_unittest.cc \
    googletest/googletest/samples/sample1.cc \
    bin/libgtest.a bin/libgtest_main.a \
    -o bin/a \
    && time bin/a \
)

1.对于googletest/googletest/samples/sample2_unittest.cc：

time ( \
    time g++ -Wall -Wextra -Werror -O3 -std=c++17 -pthread \
    -I"googletest/googletest/include" -I"googletest/googlemock/include" \
    googletest/googletest/samples/sample2_unittest.cc \
    googletest/googletest/samples/sample2.cc \
    bin/libgtest.a bin/libgtest_main.a \
    -o bin/a \
    && time bin/a \
)

等等。
上面构建sample1_unittest.cc的示例构建和运行命令及输出：

eRCaGuy_hello_world/cpp$ time ( \
>     time g++ -Wall -Wextra -Werror -O3 -std=c++17 -pthread \
>     -I"googletest/googletest/include" -I"googletest/googlemock/include" \
>     googletest/googletest/samples/sample1_unittest.cc \
>     googletest/googletest/samples/sample1.cc \
>     bin/libgtest.a bin/libgtest_main.a \
>     -o bin/a \
>     && time bin/a \
> )

real    0m1.787s
user    0m1.375s
sys 0m0.165s
Running main() from googletest/googletest/src/gtest_main.cc
[==========] Running 6 tests from 2 test suites.
[----------] Global test environment set-up.
[----------] 3 tests from FactorialTest
[ RUN      ] FactorialTest.Negative
[       OK ] FactorialTest.Negative (0 ms)
[ RUN      ] FactorialTest.Zero
[       OK ] FactorialTest.Zero (0 ms)
[ RUN      ] FactorialTest.Positive
[       OK ] FactorialTest.Positive (0 ms)
[----------] 3 tests from FactorialTest (0 ms total)

[----------] 3 tests from IsPrimeTest
[ RUN      ] IsPrimeTest.Negative
[       OK ] IsPrimeTest.Negative (0 ms)
[ RUN      ] IsPrimeTest.Trivial
[       OK ] IsPrimeTest.Trivial (0 ms)
[ RUN      ] IsPrimeTest.Positive
[       OK ] IsPrimeTest.Positive (0 ms)
[----------] 3 tests from IsPrimeTest (0 ms total)

[----------] Global test environment tear-down
[==========] 6 tests from 2 test suites ran. (0 ms total)
[  PASSED  ] 6 tests.

real    0m0.003s
user    0m0.000s
sys 0m0.002s

real    0m1.790s
user    0m1.375s
sys 0m0.166s

注解

1.问：为什么在构建googletest库时需要include dir -I"googletest/googletest"？
1.答：因为googletest/googletest/src/gtest-all.cc包含所有其他源文件src/name_of_file.cc，这里：这https://github.com/google/googletest/blob/main/googletest/src/gtest-all.cc#L41-L49意味着包含src目录的父目录必须是一个“包含文件夹”。该父目录是googletest/googletest，因此我们用-I"googletest/googletest"将其标记为包含目录。
1.你也可以用gtest测试C代码，当在C中包含C头文件时使用extern "C" { }技巧来防止名称损坏，然后链接到C构建的对象*.o文件，同时在C googletest单元测试中包含非名称损坏的头文件。
快乐构建！现在我/我们终于可以在我们自己的个人项目中轻松使用gtest了！

其他参考文献：

1.我自己的答案，我计算出了time cmd Package 器的事情，以计时一个更大的多行命令的子组件，以及整个多行命令：How to run time on multiple commands AND write the time output to file?

• 有关更多手动方法，请参见my other answer here *。

简单的方法：分别在/usr/local/include和/usr/local/lib中安装gtest的头文件和.a静态库文件

又经过了一年的努力，总共花了5年时间，我终于找到了“简单”的方法。
我最初只是想知道运行什么g++命令来构建我自己的单元测试文件。
1.将gtest和gmock作为静态的.a共享库安装在/usr/local/lib/中，并将它们的头文件安装到/usr/local/include/中。

sudo apt update
sudo apt install cmake

# You can find some of these instructions, here: 
# https://github.com/google/googletest/tree/main/googletest
time git clone https://github.com/google/googletest.git
cd googletest        # "Main directory of the cloned repository."
mkdir build          # "Create a directory to hold the build output."
cd build
time cmake ..        # "Generate native make build scripts for GoogleTest."
                        # Takes ~2 seconds.
time make            # Run those makefiles just autogenerated by cmake above.
                        # Takes ~10 seconds.
sudo make install    # Install the .a library files, and headers, into 
                        # /user/local/.

1.根据需要使用直接传递给g++的-pthread、-lgtest、-lgtest_main、-lgmock和-lgmock_main链接器标志。
示例：

# Build and run an example googletest unit test that comes in the repo:
# - required in this case: `-pthread`, `-lgtest`, and `-lgtest_main`

mkdir -p bin

time g++ -Wall -Wextra -Werror -O3 -std=c++17 -pthread \
    googletest/googletest/samples/sample1_unittest.cc \
    googletest/googletest/samples/sample1.cc \
    -lgtest -lgtest_main -o bin/a && time bin/a

要了解吨更多细节、更长的解释和更多信息，请参阅我的完整答案：快！
有关-l标志的更多信息，另请参见我的其他回答：Meaning of -l (lowercase "L") flags in gcc/g++