CMake: Enforcing Execution Order between Sibling Target Dependencies - cmake

Question

I would like to enforce the execution order of sibling dependencies. Let's assume we have the following top-level targets:
add_custom_target(test_all)
add_custom_target(test_coverage)
add_custom_target(test_coverage_zero)
add_custom_target(test_coverage_collect)
I'm using test_all to execute unit tests (and possibly build them and their dependencies). test_coverage should execute test_coverage_zero, then test_all, and finally test_coverage_collect. test_coverage_zero will cleanup leftover coverage data from a previous run of test_all, while test_coverage_collect uses the current coverage data and produces some kind human-readable output. The reason for this setup is to allow test_all to be executed without actual coverage data processing. On the other hand test_coverage needs to execute test_all to produce coverage data.
[Detail: I'm using gcov/lcov for the coverage data and added custom commands to test_coverage_zero and test_coverage_collect for the actual processing.]
I've setup the following dependencies to achieve this behavior:
add_dependencies(test_coverage test_coverage_zero test_all test_coverage_collect)
That does not work. The actual execution order is test_all, test_coverage_zero, and test_coverage_collect, which removes the coverage data before the collection step.
My question: How do I enforce the order of target dependencies (on the sibling level) in CMake?

Answer 1

Looks like the answer is:
add_dependencies(test_all test_coverage_zero)
add_dependencies(test_coverage_collect test_all)
add_dependencies(test_coverage test_coverage_zero test_all test_coverage_collect)
However, removing either test_coverage_zero or test_all from the last dependency will also not work, even though there's a clear dependency chain test_coverage<-test_coverage_collect<-test_all<-test_coverage_zero.