Add conftest.py for db tests

test/unit/data/model/db/conftest.py

@@ -0,0 +1,53 @@
+from typing import (
+    Generator,
+    TYPE_CHECKING,
+)
+
+import pytest
+from sqlalchemy import (
+    create_engine,
+    text,
+)
+from sqlalchemy.orm import Session
+
+from galaxy import model as m
+
+if TYPE_CHECKING:
+    from sqlalchemy.engine import Engine
+
+
+@pytest.fixture(scope="module")
+def db_url() -> str:
+    """
+    By default, use an in-memory database.
+    To overwrite, add this fixture with a new db url to a test module.
+    """
+    return "sqlite:///:memory:"
+
+
+@pytest.fixture(scope="module")
+def engine(db_url: str) -> "Engine":
+    return create_engine(db_url)
+
+
+@pytest.fixture
+def session(engine: "Engine") -> Session:
+    return Session(engine)
+
+
+@pytest.fixture(autouse=True, scope="module")
+def init_database(engine: "Engine") -> None:
+    """Create database objects."""
+    m.mapper_registry.metadata.create_all(engine)
+
+
+@pytest.fixture(autouse=True)
+def clear_database(engine: "Engine") -> "Generator":
+    """Delete all rows from all tables. Called after each test."""
+    yield
+    with engine.begin() as conn:
+        for table in m.mapper_registry.metadata.tables:
+            # Unless db is sqlite, disable foreign key constraints to delete out of order
+            if engine.name != "sqlite":
+                conn.execute(text(f"ALTER TABLE {table} DISABLE TRIGGER ALL"))
+            conn.execute(text(f"DELETE FROM {table}"))