Grouping the unit tests together in CMake - unit-testing

Question

I have different test builds within CMake, with the last one running ALL the tests.
Does the last test UTestAll build each unit test separately and if so, does that mean the same test ends up getting built multiple times? Perhaps there's a way to group the unit tests such that it's only built once?
Or rather, is there a way to have the option to exclude a particular target from running? So say at some point I wouldn't want to run UTestAll when running on jenkins pipeline but would want to run locally.
#Test1
set(THIS UTest1)
string(TOUPPER DO_BUILD_${THIS} THIS_FLAG)
if (${THIS_FLAG})
add_executable(
${THIS}
src/Test1.cpp
)
target_include_directories(${THIS} PRIVATE include)
target_link_libraries(${THIS} PUBLIC lib1
endif()
#Test2
set(THIS UTest2)
string(TOUPPER DO_BUILD_${THIS} THIS_FLAG)
if (${THIS_FLAG})
add_executable(
${THIS}
src/Test2.cpp
)
target_include_directories(${THIS} PRIVATE include)
target_link_libraries(${THIS} PUBLIC lib2
endif()
#Test3
set(THIS UTest3)
string(TOUPPER DO_BUILD_${THIS} THIS_FLAG)
if (${THIS_FLAG})
add_executable(
${THIS}
src/Test3.cpp
)
target_include_directories(${THIS} PRIVATE include)
target_link_libraries(${THIS} PUBLIC lib3
endif()
# Run ALL Tests
set(THIS UTestAll)
string(TOUPPER DO_BUILD_${THIS} THIS_FLAG)
if (${THIS_FLAG})
add_executable(
${THIS}
src/Test1.cpp
src/Test2.cpp
src/Test3.cpp
)
target_include_directories(${THIS} PRIVATE include)
target_link_libraries(${THIS} PUBLIC lib1 lib2 lib3
endif()

Answer 1

Basically you can build each test as an object library, make an executable from each of that and then another one using all of them as follows:
# add object library for each file
add_library(UTest1_obj OBJECT)
target_sources(UTest1_obj PRIVATE src/Test1.cpp)
target_include_directories(UTest1_obj PRIVATE include)
[...]
# add executables linking one object each
add_executable(UTest1)
target_link_libraries(UTest1 PRIVATE UTest1_obj)
[...]
# add an executable with all objects
add_executable(UTestAll)
target_link_libraries(UTestAll PRIVATE UTest1_obj UTest2_obj UTest3_obj)
It may make sense to take a look at CMake macros, so it isn't that repetetive.
It may also make sense to look into ctest and some testing framework (GoogleTest, Catch2 or something like that)