In file included from /in/piece.cpp:2:0:
/in/compile/piece.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/pool.cpp:1:0:
/in/compile/pool.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/square.cpp:1:0:
/in/compile/square.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/board.cpp:1:0:
/in/compile/board.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/compile/player.h:4:0,
                 from /in/player.cpp:1:
/in/compile/board.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/compile/player.h:4:0,
                 from /in/game.cpp:3:
/in/compile/board.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /in/compile/exceptions.h:4:0,
                 from /in/compile/exceptions.cpp:2:
/in/compile/pool.h:4:10: fatal error: gtest/gtest_prod.h: No such file or directory
 #include <gtest/gtest_prod.h>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.