feat(pytest): add session fixture to run db migrations (#18)

Author: hadrien

README.md

@@ -203,3 +203,23 @@ def patient(session):
     session.commit()
     return patient
 ```
+
+### `db_migration`
+
+A session scope fixture that runs `alembic upgrade` at test session setup and
+`alembic downgrade` at tear down.
+
+It depends on `alembic_ini_path` fixture to get the path of `alembic.ini` file.
+
+To use:
+
+```python
+from pytest import mark
+
+pytestmark = mark.usefixtures("db_migration")
+```
+
+### `alembic_ini_path`
+
+It returns the path of  `alembic.ini` configuration file. By default, it returns
+`./alembic.ini`.

fastapi_sqla/_pytest_plugin.py

@@ -1,6 +1,8 @@
 import os
 from unittest.mock import patch
 
+from alembic import command
+from alembic.config import Config
 from pytest import fixture
 from sqlalchemy import create_engine
 
@@ -26,8 +28,30 @@ def sqla_connection(db_url):
     connection.close()
 
 
+@fixture(scope="session")
+def alembic_ini_path():  # pragma: no cover
+    """Path for alembic.ini file, defaults to `./alembic.ini`."""
+    return "./alembic.ini"
+
+
+@fixture(scope="session")
+def db_migration(db_url, sqla_connection, alembic_ini_path):
+    """Run alembic upgrade at test session setup and downgrade at tear down.
+
+    Override fixture `alembic_ini_path` to change path of `alembic.ini` file.
+    """
+    alembic_config = Config(file_=alembic_ini_path)
+    alembic_config.set_main_option("sqlalchemy.url", db_url)
+
+    sqla_connection.execute("DROP SCHEMA public CASCADE; CREATE SCHEMA public;")
+
+    command.upgrade(alembic_config, "head")
+    yield
+    command.downgrade(alembic_config, "base")
+
+
 @fixture
-def sqla_modules():  # pragma: no cover
+def sqla_modules():
     raise Exception(
         "sqla_modules fixture is not defined. Define a sqla_modules fixture which "
         "imports all modules with sqla entities deriving from fastapi_sqla.Base ."

poetry.lock

@@ -24,6 +24,7 @@ asgi_lifespan = "^1.0.1"
 httpx = "^0.15.4"
 pytest-asyncio = "^0.14.0"
 Faker = "^4.5.0"
+alembic = "^1.4.3"
 
 [build-system]
 requires = ["poetry>=0.12"]

pyproject.toml

@@ -0,0 +1,2 @@
+[alembic]
+script_location = %(here)s/db

tests/alembic.ini

@@ -0,0 +1,16 @@
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+config = context.config
+
+connectable = engine_from_config(
+    config.get_section(config.config_ini_section),
+    prefix="sqlalchemy.",
+    poolclass=pool.NullPool,
+)
+
+with connectable.connect() as connection:
+    context.configure(connection=connection, target_metadata=None)
+
+    with context.begin_transaction():
+        context.run_migrations()

tests/db/env.py

@@ -0,0 +1,27 @@
+"""create user table to test
+
+Revision ID: 01
+Revises:
+Create Date: 2020-12-23 12:08:57.382420
+
+"""
+from alembic import op
+from sqlalchemy import Column, Integer, String
+
+# revision identifiers, used by Alembic.
+revision = "01"
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        "testuser",
+        Column("id", Integer, primary_key=True, autoincrement=True),
+        Column("name", String, nullable=False),
+    )
+
+
+def downgrade():
+    op.drop_table("testuser")

tests/db/versions/01_create_user_table_to_test.py

@@ -0,0 +1,12 @@
+from pytest import fixture, mark
+
+pytestmark = mark.usefixtures("db_migration")
+
+
+@fixture(scope="session")
+def alembic_ini_path():
+    return "./tests/alembic.ini"
+
+
+def test_it(session):
+    session.execute("select * from testuser")