cmake: how to separately compile production code and test code - unit-testing

Question

I read this brilliant tutorial about how to integrate Google Test with CMake. The outline of the project there looks like this:
+-- CMakeLists.txt
+-- main
| +-- CMakeLists
| +-- main.cpp
|
+-- test
| +-- CMakeLists.txt
| +-- testfoo
| +-- CMakeLists.txt
| +-- main.cpp
| +-- testfoo.h
| +-- testfoo.cpp
| +-- mockbar.h
|
+-- libfoo
| +-- CMakeLists.txt
| +-- foo.h
| +-- foo.cpp
|
+-- libbar
+-- CMakeLists.txt
+-- bar.h
+-- bar.cpp
(For the interested, the entire code of this example project can be checked out from here)
The top-level CMakeLists.txt contains (among others) the statements enable_testing() and add_subdirectory(test). Compiling and running test cases works perfectly with this setup, simply by running
mkdir build && cd build
cmake ..
make
make test
But how would I compile this project into production code, i.e. only the components test, libfoo and libbar, without all the unit tests?
Should I make the statements enable_testing() and add_subdirectory(test) somehow dependent on some build configuration variables? Or what's the best practice for this?

Answer 1

To build the tests only on request, I do it in this way:
Add an option option(BUILD_TEST "Build the unit tests" ON)
Include the test subdirs only in case BUILD_TEST is on
if(BUILD_TEST)
add_subdirectory(test)
endif()
In your case you can modify this to testfoo.
As you asked for production, you can use the following instead to build in debug mode only:
if("${CMAKE_BUILD_TYPE}" STREQUAL "Debug")
add_subdirectory(test)
endif()

Answer 2

What I do is to make a custom macro for unit test creation which does this:
set_target_properties(${NAME} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/test)
Then your tests will end up in a special directory (test) instead of the regular one (usually bin). Then for production you just copy the regular directory without the test directory.