switch pool for sqlite with new factory, add tests if fks are reflected in db

tests/test_database_fk_creation.py

@@ -0,0 +1,55 @@
+from typing import Optional
+
+import databases
+import pytest
+import sqlalchemy
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL)
+metadata = sqlalchemy.MetaData()
+engine = sqlalchemy.create_engine(DATABASE_URL)
+
+
+class Artist(ormar.Model):
+    class Meta:
+        tablename = "artists"
+        metadata = metadata
+        database = database
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+
+
+class Album(ormar.Model):
+    class Meta:
+        tablename = "albums"
+        metadata = metadata
+        database = database
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+    artist: Optional[Artist] = ormar.ForeignKey(Artist, ondelete="CASCADE")
+
+
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    metadata.drop_all(engine)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+def test_simple_cascade():
+    inspector = sqlalchemy.inspect(engine)
+    columns = inspector.get_columns("albums")
+    assert len(columns) == 3
+    col_names = [col.get("name") for col in columns]
+    assert sorted(["id", "name", "artist"]) == sorted(col_names)
+    fks = inspector.get_foreign_keys("albums")
+    assert len(fks) == 1
+    assert fks[0]["name"] == "fk_albums_artists_id_artist"
+    assert fks[0]["constrained_columns"][0] == "artist"
+    assert fks[0]["referred_columns"][0] == "id"
+    assert fks[0]["options"].get("ondelete") == "CASCADE"