CMake: avoid building tests by default [duplicate] - cmake

Question

I have a small project with cmake. I build a lib and an executable. on the development machine I want also an executable that cannot be build on other machines/environments.
e.g.:
<my-lib>
| -- CMakeLists.txt
|
+ -- src/ -> build the lib/archive
| |-- lib.c
| |-- lib.h
| |-- CMakeLists.txt
|
+ -- tool -> build the tool
| |-- tool.c
| |-- CMakeLists.txt
|
+ -- tests -> build the unit tests
| |-- tests.c
| |-- CMakeLists.txt
I added CMakeLists.txt to all directories. Also an add_executable to the tests. Now the unit-test executable is build by default. But I want to exclude it from default target.
CMakeLists.txt in tests:
find_library (CUNIT_LIB cunit)
include_directories (${Cunit_INCLUDE_DIRS} "${PROJECT_SOURCE_DIR}/src")
set (CMAKE_C_FLAGS "-O2 -Wall -Werror")
add_executable (unit-test tests.c)
target_link_libraries (unit-test my-lib cunit)
Has anyone a hint how to handle this? I don't want to build unit-test always!

Answer 1

There is a property EXCLUDE_FROM_ALL for such task.
You can write:
set_target_properties(unit-test PROPERTIES EXCLUDE_FROM_ALL TRUE)

Answer 2

This is very simple: protect creation of executable by introducing an option/variable.
if (DEFINED WITH_UNIT_TEST)
find_library (CUNIT_LIB cunit)
include_directories (${Cunit_INCLUDE_DIRS} "${PROJECT_SOURCE_DIR}/src")
set (CMAKE_C_FLAGS "-O2 -Wall -Werror")
add_executable (unit-test tests.c)
target_link_libraries (unit-test my-lib cunit)
endif ()
Now when invoking CMake, one would have to explicitly specify -DWITH_UNIT_TEST, so that unit-test target is built, while by default it will never be build. For alternative approach, see comments.