Every postgresql testcase essentially does the following things:
* Filter `postgresqlVersions` for server packages
* Filter postgresql server packages for suitable ones (i.e. extensions
must support the given version)
* Generate an attribute-set of testcases
The first item became necessary in
7ab1e88833 given that
`postgresql/default.nix` now exposes JIT and non-JIT servers AND a
`libpq` that is not suitable for the tests here.
This changes restructures this a little bit, i.e.:
* Having an attribute-set that contains a bunch of postgresql servers
and a single client package seems odd (and the sole consumer of
`postgresqlVersions` in nixpkgs, the test suite, has to take that into
account). Hence, postgresql's default.nix now provides `libpq` (the client)
and a `postgresqlVersions` attribute with all supported JIT and non-JIT
variants of postgresql.
* Each test-case gets a third argument, a function called `genTests`:
this function sets `recurseForDerivations = true;` and generates an
attribute-set of tests for each postgresql version given a function
that returns a testcase or multiple test-cases (`makeTestFor`). The
argument to `makeTestFor` is a postgresql server package.
This function also accepts a filter predicate that is passed against
`filterAttrs` to remove postgresql server packages that are not
suitable for the test (e.g. because the version isn't supported by the
extension to test).
I checked by making sure that the `.drv` doesn't change on staging with
this change on top for postgresq, postgresql-jit,
postgresql-wal-receiver, postgresql-tls-client-cert, anonymizer, pgjwt,
pgvecto-rs, timescaledb, tsja and wal2json.
