Package: pytest-alembic
See the full documentationhere.IntroductionA pytest plugin to test alembic migrations (with default tests) and
which enables you to write tests specific to your migrations.$pipinstallpytest-alembic
$pytest--test-alembic

...
::pytest_alembic/tests/model_definitions_match_ddl<-.PASSED[25%]::pytest_alembic/tests/single_head_revision<-.PASSED[50%]::pytest_alembic/tests/up_down_consistency<-.PASSED[75%]::pytest_alembic/tests/upgrade<-.PASSED[100%]==============================4passedin2.32s===============================The pitchHave you ever merged a change to your models and you forgot to generate
a migration?Have you ever written a migration only to realize that it fails when
there’s data in the table?Have you ever written aperfectmigration only to merge it and later
find out that someone else merged also merged a migration and your CD is
now broken!?pytest-alembicis meant to (with a little help) solve all these
problems and more. Note, due to a few different factors, theremaybe someminimal required
setup;
however most of it is boilerplate akin to the setup required for alembic
itself.Built-in Teststest_single_head_revisionAssert that there only exists one head revision.We’re not sure what realistic scenario involves a diverging history to
be desirable. We have only seen it be the result of uncaught merge
conflicts resulting in a diverged history, which lazily breaks during
deployment.test_upgradeAssert that the revision history can be run through from base to head.test_model_definitions_match_ddlAssert that the state of the migrations matches the state of the
models describing the DDL.In general, the set of migrations in the history should coalesce into
DDL which is described by the current set of models. Therefore, a call
torevision --autogenerateshould always generate an empty migration
(e.g. find no difference between your database (i.e. migrations
history) and your models).test_up_down_consistencyAssert that all downgrades succeed.While downgrading may not be lossless operation data-wise, there’s a
theory of database migrations that says that the revisions in
existence for a database should be able to go from an entirely blank
schema to the finished product, and back again.Experimental
testsall_models_register_on_metadataAssert that all defined models are imported statically.Prevents scenarios in which the minimal import of your models in yourenv.pydoes not import all extant models, leading alembic to not autogenerate all
your models, or (worse!) suggest the deletion of tables which should still exist.downgrade_leaves_no_traceAssert that there is no difference between the state of the database pre/post downgrade.In essence this is a much more strict version oftest_up_down_consistency,
where the state of a MetaData before and after a downgrade are identical as
far as alembic (autogenerate) is concerned.These tests will need to be enabled manually because their semantics or API are
not yet guaranteed to stay the same. See the linked docs for more details!Let us know if you have any ideas for more built-in tests which would be
generally useful for most alembic histories!Custom TestsFor more information, see the docs forcustom
tests(example below) orcustom static
data(to be inserted automatically before a given revision).Sometimes when writing a particularly gnarly data migration, it helps to
be able to practice a little timely TDD, since there’s always the
potential you’ll trash your actual production data.Withpytest-alembic, you can write tests directly, in the same way
that you would normally, through the use of thealembic_runnerfixture.deftest_gnarly_migration_xyz123(alembic_engine,alembic_runner):# Migrate up to, but not including this new migrationalembic_runner.migrate_up_before('xyz123')# Perform some very specific data setup, because this migration is sooooo complex.# ...alembic_engine.execute(table.insert(id=1,name='foo'))alembic_runner.migrate_up_one()alembic_runnerhas a number of methods designed to make it convenient
to change the state of your database up, down, and all around.Installingpipinstall"pytest-alembic"