There were 2 separate bugs, one recently added and one ancient
(since roughly the first version of the registration script).
1) The recent refactoring of how the JSON output from Catch2 is
parsed caused shadowing between the variable containing the
per-test JSON fragments and the accumulator of test names for
<target>_TESTS variable. This led to the variable containing
both the names and the JSON fragments, and thus being completely
wrong.
2) The test name accumulation has never accounted for characters
that need escaping to be present in a CMake list. This means
that e.g. test names with semicolon in them would end up with
two elements in the test list.
Both of these are now fixed, at the cost of extra complexity and
my sanity as I had to learn more about CMake escaping rules.
(CMake escaping rules are dumb)
Using CMake's `string(JSON` to parse JSON array leads to quadratic
running time in number of tests, see https://gitlab.kitware.com/cmake/cmake/-/work_items/27985
This leads to _terrible_ runtime for `catch_discover_tests` when called
on binaries with lot of tests (1k+). To get reasonable runtimes, we have
to avoid using `string(JSON` to parse out the individual test objects
from the array with all tests.
This commit replaces the sane approach of using real JSON parser with
a set of terrible hacks, where we use CMake's string APIs to split the
JSON array on what looks like object boundary (`}<ws>*,<ws>*{`), and then
checking whether the resulting thing can be parsed as JSON object. If not,
we append the next piece and check again. And again, and again, until we
get a proper JSON object.
This is all around a hilariously terrible idea, however:
1) It works in practice for all tested inputs.
2) It improves the time it takes to run `catch_discover_tests` on binary
with 1k tests from 4.2s to 1.1s and 2k tests from 16s to 3.9s.
Martin Hořeňovský
Robin Christ