cmake: Add UniValue tests to the ctest suit

[hebasto]

As it was pointed out by TheCharlatan and fanquake during the recent offline meeting, since bitcoin#25369, the Univalue unit tests must be included to the ctest suit.

[hebasto]

Rebased.

[hebasto]

Rebased and undrafted.

[theuni]

ACK d554706. Looks good, built and ran locally. Tried changing JSON_TEST_SRC to a nonsense value and things broke as expected.

[theuni]

Out of curiosity, why are these defined here rather than inline with the build rules?

Specifically here, why not do the add_test in src/univalue/CMakeLists.txt ?

I don't have any objection, I just keep forgetting to ask.

[hebasto]

The ctest executable looks for tests in the current directory, which can be specified explicitly using the --test-dir option in CTest >=3.20. When using the add_test command in CMake, a new test is placed into the build tree with the same relative path as the location of the file, which executes the command, in the source tree. This behavior is consistent with how the add_executable and add_library commands work.

Therefore, the purpose of the cmake/tests.cmake file is to collect all add_test commands, ensuring that all tests are discoverable by ctest within a single directory.

EDIT. Please ignore this comment.

[hebasto]

@theuni

My previous comment is not correct. It was based on the buggy behavior that has been fixed in bfe7c4d.

Please see #275.

[sedited]

ACK d554706

[pablomartin4btc]

post-merge tACK d554706

Verified the UniValue tests were added (before total was 125, now 127)

        Start 126: univalue_test
111/127 Test #126: univalue_test ...............................................................   Passed    0.02 sec
        Start 127: univalue_object_test
112/127 Test #127: univalue_object_test ........................................................   Passed    0.00 sec