Gtest: Undefined References

Question

I am trying to use GoogleTest to test a simple function, but as I run make in my build folder, the compiler throws Undefined Reference error messag

Answer 1

Put the libgtest.a after your object files

If you are doing things manually instead of with CMake, make sure to do:

g++ main.cpp googletest/build/lib/libgtest.a

instead of:

g++ googletest/build/lib/libgtest.a main.cpp

Here's a full working example I've tested with: https://askubuntu.com/questions/97626/how-to-install-googletest/1295185#1295185

This problem is not exclusive to GoogleTest: I can also reproduce it with a minimal library example like this one and Eli explainss the ordering rules which I don't have the patience to learn right now.

Answer 2

Your setup looks to be almost correct. However, you're needing to have 2 separate main functions; one for the real executable Proj2 and another with the gtest includes and functions for the test executable unit-test.

You could do this by having 2 different main.cpp files, say main.cpp and test_main.cpp. The one you've shown would be test_main.cpp, and would be included in the add_executable(unit-test ... command.

Your new main.cpp would have no references to gtest, either includes or functions.

Answer 3

From linker errors it is obvious that you did not link gtest library to your test program.

See Primer:

To write a test program using Google Test, you need to compile Google Test into a library and link your test with it. ...

Just see this doc for details about your compiler and system.