Tests don't work with -DEXTERNAL_CHIPDB=ON

[GyrosGeier]

When installing the chipdb to separate files, tests are looking for the files in the installed path, where they only exist if this or a previous version is already installed.

As a result, tests cannot run as part of a package build in a clean environment.

In an environment where the previous version is installed, the tests use the chipdb files from the previous version instead of the just-built ones.

As a horrible hack, it works with

    add_definitions("-DEXTERNAL_CHIPDB_ROOT=\"$<IF:$<STREQUAL:$<LIST:FILTER,$<TARGET_PROPERTY:NAME>,INCLUDE,.*-test>,>,${EXTERNAL_CHIPDB_ROOT},$<PATH:REMOVE_FILENAME,$<TARGET_PROPERTY:BINARY_DIR>>>\"")

in the toplevel CMakeLists. I think this solution is problematic for a lot of reasons, so it's not a pull request, but it would be cool to have a way to run tests reliably with -DEXTERNAL_CHIPDB=ON.

[whitequark]

When implementing -DEXTERNAL_CHIPDB=ON I never considered the tests. In my mind, developers run the tests, and they build the chipdb in-tree.

I don't consider it necessary so I'm not going to implement support for this, but I will review and merge a patch that's sufficiently clean.

[GyrosGeier]

We run the tests as part of the Debian package build, that should catch problems on obscure architectures a bit earlier, and we use -DEXTERNAL_CHIPDB so we only need to keep one copy in the archive that is shared between all platforms and the gui/non-gui packages.

Not an urgent problem because the horrible hack appears to work (but likely also increases build time), but having an official mechanism to run tests on a freshly built tree in a clean chroot would be great.

I was thinking of using an environment variable here, but I don't like that either.