Minify googletest into lib

[gigafiga21]

Try to compile googletest into library to avoid complicated makefile in tests directory

[gigafiga21]

It is possible to compile googletest into a shared library, as said here:
https://github.com/google/googletest/blob/master/googletest/README.md

[gigafiga21]

More readable instruction:
https://stackoverflow.com/questions/51815686/how-to-build-and-use-googletest-shared-library-so-using-g-on-linux

[gigafiga21]

If fatal error: 'src/gtest.cc' file not found rake found, this may help:
https://stackoverflow.com/questions/43125946/g-fatal-error-when-compiling-google-test

[gigafiga21]

To fight this, add -std=c++11 flag:

./include/gtest/internal/gtest-port.h:838:12: error: no member named 'make_tuple' in namespace 'std'
using std::make_tuple;

google/googletest#1519

[gigafiga21]

Compiling:

g++ -std=c++11 -fPIC -isystem ./googletest/include -I ./googletest/ -pthread -c ./googletest/src/gtest-all.cc -DGTEST_CREATE_SHARED_LIBRARY=1

Creating dynamic library:

g++ -fPIC -shared gtest-all.o -o libgtest.so -DGTEST_LINKED_AS_SHARED_LIBRARY=1

Creating static library:

ar rvs libgtest.a gtest-all.o

[gigafiga21]

Compile tests:

For project with structure

* gtest
    - ...
    - gtest.h
    - libgtest.a
- sum.cpp
- test.cpp

Where test.cpp contains main function for starting tests, sum.cpp - file with testing functional.
This command will be suitable:

g++ test.cpp -I ./ -L ./gtest -lgtest -o test -std=c++11

[gigafiga21]

Open question:

Use self-compiled library or default Linux packages?
@Hemmemm