diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index c76662d..92f3023 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -46,11 +46,12 @@ dev-dependencies = [
     "pre-commit>=3.5.0",
     "ruff>=0.5.1",
     "pytest-cov>=4.1.0",
-    "pytest-asyncio>=0.23.7",
+    "pytest-asyncio==0.20.3", # breaking change in 0.23: https://github.com/pytest-dev/pytest-asyncio/issues/706
     "black>=23.12.1",
     "mypy>=1.8.0",
     "pytest-sugar>=1.0.0",
     "pytest-tldr>=0.2.5",
+    "polyfactory>=2.16.0",
 ]
 
 [tool.hatch.metadata]
@@ -89,7 +90,7 @@ fixable = ["ALL"]
 
 [tool.ruff.lint.extend-per-file-ignores]
 "env.py" = ["INP001", "I001", "ERA001"]
-"tests/*.py" = ["S101", "ANN201", "PLR2004"]
+"tests/*.py" = ["S101", "ANN201", "PLR2004", "ANN001"]
 "*exceptions.py" = ["ARG001"]
 "models.py" = ["RUF012"]
 "schemas.py" = ["ANN201"]
diff --git a/backend/requirements-dev.lock b/backend/requirements-dev.lock
index 42f392d..a79e63a 100644
--- a/backend/requirements-dev.lock
+++ b/backend/requirements-dev.lock
@@ -63,6 +63,8 @@ dnspython==2.5.0
 email-validator==2.1.0.post1
     # via fastapi
     # via netsight
+faker==26.0.0
+    # via polyfactory
 fastapi==0.111.0
     # via netsight
 fastapi-cli==0.0.4
@@ -144,6 +146,7 @@ platformdirs==4.1.0
     # via virtualenv
 pluggy==1.3.0
     # via pytest
+polyfactory==2.16.0
 pre-commit==3.6.0
 prompt-toolkit==3.0.47
     # via click-repl
@@ -172,12 +175,13 @@ pytest==7.4.4
     # via pytest-cov
     # via pytest-sugar
     # via pytest-tldr
-pytest-asyncio==0.23.7
+pytest-asyncio==0.20.3
 pytest-cov==4.1.0
 pytest-sugar==1.0.0
 pytest-tldr==0.2.5
 python-dateutil==2.8.2
     # via celery
+    # via faker
     # via pandas
 python-dotenv==1.0.0
     # via pydantic-settings
@@ -231,6 +235,7 @@ typing-extensions==4.9.0
     # via alembic
     # via fastapi
     # via mypy
+    # via polyfactory
     # via pydantic
     # via pydantic-core
     # via sqlalchemy
diff --git a/backend/src/core/database/session.py b/backend/src/core/database/session.py
index a5b563f..c9ac3fb 100644
--- a/backend/src/core/database/session.py
+++ b/backend/src/core/database/session.py
@@ -1,24 +1,17 @@
 import logging
 
 from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
-from sqlalchemy.pool import NullPool
 
-from src.core.config import _Env, settings
+from src.core.config import settings
 
 logger = logging.getLogger(__name__)
 
-if _Env.PROD.name == settings.ENV:
-    async_engine = create_async_engine(
-        url=settings.SQLALCHEMY_DATABASE_URI,
-        pool_pre_ping=True,
-        future=True,
-        pool_size=settings.DATABASE_POOL_SIZE,
-        connect_args={"server_settings": {"jit": "off"}},
-        max_overflow=settings.DATABASE_POOL_MAX_OVERFLOW,
-    )
-else:
-    # compatibility with pytest
-    async_engine = create_async_engine(
-        url=settings.SQLALCHEMY_DATABASE_URI, pool_pre_ping=True, future=True, poolclass=NullPool
-    )
+async_engine = create_async_engine(
+    url=settings.SQLALCHEMY_DATABASE_URI,
+    pool_pre_ping=True,
+    future=True,
+    pool_size=settings.DATABASE_POOL_SIZE,
+    connect_args={"server_settings": {"jit": "off"}},
+    max_overflow=settings.DATABASE_POOL_MAX_OVERFLOW,
+)
 async_session = async_sessionmaker(async_engine, autoflush=False, expire_on_commit=False)
diff --git a/backend/src/features/deps.py b/backend/src/features/deps.py
index 7f8776f..3d4b402 100644
--- a/backend/src/features/deps.py
+++ b/backend/src/features/deps.py
@@ -25,15 +25,15 @@
 token = HTTPBearer()
 
 
-async def get_session() -> AsyncGenerator["AsyncSession", None]:
-    async with async_session() as session:
-        try:
-            yield session
-        except SQLAlchemyError as e:
-            logger.exception("Database error: %s", e)  # noqa: TRY401
-            await session.rollback()
-        finally:
-            await session.aclose()
+async def get_session() -> AsyncGenerator[AsyncSession, None]:
+    session: AsyncSession = async_session()
+    try:
+        yield session
+    except SQLAlchemyError as e:
+        logger.exception("Database error: %s", e)  # noqa: TRY401
+        await session.rollback()
+    finally:
+        await session.aclose()
 
 
 async def auth(
diff --git a/backend/src/features/org/schemas.py b/backend/src/features/org/schemas.py
index 2bebeab..aa310a9 100644
--- a/backend/src/features/org/schemas.py
+++ b/backend/src/features/org/schemas.py
@@ -53,7 +53,7 @@ class SiteBase(BaseModel):
     address: str
     latitude: float
     longitude: float
-    classfication: str | None = None
+    classification: str | None = None
     comments: str | None
 
 
diff --git a/backend/tests/factoreis.py b/backend/tests/factoreis.py
index 9b9682a..49f2917 100644
--- a/backend/tests/factoreis.py
+++ b/backend/tests/factoreis.py
@@ -1,8 +1,11 @@
+from polyfactory.factories.pydantic_factory import ModelFactory
 from polyfactory.factories.sqlalchemy_factory import SQLAlchemyFactory
 from polyfactory.fields import Ignore
 
 from src.features.admin.models import Group, Menu, Permission, Role, User
 from src.features.admin.security import get_password_hash
+from src.features.org import models as org_models
+from src.features.org import schemas as org_schemas
 
 
 class UserFactory(SQLAlchemyFactory[User]):
@@ -35,3 +38,20 @@ class MenuFactory(SQLAlchemyFactory[Menu]):
     id = Ignore()
 
     permission = [1, 2, 3, 4]  # noqa: RUF012
+
+
+class SiteCreateFactory(ModelFactory[org_schemas.SiteCreate]):
+    __model__ = org_schemas.SiteCreate
+
+
+class SiteGroupCreateFactory(ModelFactory[org_schemas.SiteGroupCreate]):
+    __model__ = org_schemas.SiteGroupCreate
+
+
+class SiteFactory(SQLAlchemyFactory[org_models.Site]):
+    __model__ = org_models.Site
+    __set_foreign_keys__ = False
+    id = Ignore()
+    status = "Active"
+    country = "China"
+    time_zone = 8