A test suite for exercising both the libpq client and the server backend at the
protocol level, based on pytest and Construct.

WARNING! This suite takes superuser-level control of the cluster under test,
writing to the server config, creating and destroying databases, etc. It also
spins up various ephemeral TCP services. This is not safe for production servers
and therefore must be explicitly opted into by setting PG_TEST_EXTRA=python in
the environment.

## Requirements

A supported version (3.6+) of Python, and a local installation of Postgres to
test. Client tests require a linkable libpq; server tests require either
`pg_ctl` in the PATH (if using `make installcheck` or `py.test --temp-instance`)
or a running server to connect to.

The first run of

    make installcheck PG_TEST_EXTRA=python

will install a local virtual environment and all needed dependencies. During
development, if libpq changes incompatibly, you can issue

    $ make rebuild-psycopg2

to force a rebuild of the client library.

If you're testing an already-running server, the test suite currently assumes
that the standard PG* environment variables point to the database under test and
are sufficient to log in a superuser on that system. In other words, a bare
`psql` needs to Just Work before the test suite can do its thing. For a newly
built dev cluster, typically all that I need to do is a

    export PGDATABASE=postgres

but you can adjust as needed for your setup. See also 'Advanced Usage' below.

## Hacking

The code style is enforced by a _very_ opinionated autoformatter. Running the

    make indent

recipe will invoke it for you automatically. Don't fight the tool; part of the
zen is in knowing that if the formatter makes your code ugly, there's probably a
cleaner way to write your code.

## Advanced Usage

The Makefile is there for convenience, but you don't have to use it. Activate
the virtualenv to be able to use pytest directly:

    $ export PG_TEST_EXTRA=python
    $ source venv/bin/activate
    $ py.test -k oauth
    ...
    $ py.test ./server/test_server.py
    ...
    $ deactivate  # puts the PATH et al back the way it was before

To make quick smoke tests possible, slow tests have been marked explicitly. You
can skip them by saying e.g.

    $ py.test -m 'not slow'

If you'd rather not test against an existing server, you can have the suite spin
up a temporary one using whatever pg_ctl it finds in PATH:

    $ py.test --temp-instance=./tmp_check