diff --git a/tests/test_db_session.py b/tests/test_db_session.py
new file mode 100644
index 0000000..258a3f9
--- /dev/null
+++ b/tests/test_db_session.py
@@ -0,0 +1,159 @@
+"""Tests for database session management."""
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from arbiter.db import session as session_module
+
+
+class TestDatabaseSession:
+    def test_reset_engine_clears_globals(self) -> None:
+        # First ensure the module level globals are in a known state
+        session_module.reset_engine()
+
+        # Verify they are cleared
+        assert session_module._engine is None
+        assert session_module._session_factory is None
+
+    async def test_get_async_session_yields_session(
+        self,
+        async_engine,
+    ) -> None:
+        # We need to use the test engine, not the production one
+        # This test uses the async_engine fixture which creates an in-memory DB
+        from sqlalchemy import text
+        from sqlalchemy.ext.asyncio import async_sessionmaker
+
+        # Set up the test engine in the module
+        session_module._engine = async_engine
+        session_module._session_factory = async_sessionmaker(
+            bind=async_engine,
+            class_=AsyncSession,
+            expire_on_commit=False,
+        )
+
+        try:
+            async for db_session in session_module.get_async_session():
+                assert isinstance(db_session, AsyncSession)
+                # Session should be usable
+                result = await db_session.execute(text("SELECT 1"))
+                assert result is not None
+        finally:
+            session_module.reset_engine()
+
+    async def test_get_async_session_commits_on_success(
+        self,
+        async_engine,
+    ) -> None:
+        from sqlalchemy import text
+        from sqlalchemy.ext.asyncio import async_sessionmaker
+
+        from arbiter.db.models import ReviewModel
+
+        # Set up the test engine
+        session_module._engine = async_engine
+        session_module._session_factory = async_sessionmaker(
+            bind=async_engine,
+            class_=AsyncSession,
+            expire_on_commit=False,
+        )
+
+        try:
+            # Create a review inside the session context
+            async for db_session in session_module.get_async_session():
+                review = ReviewModel(
+                    repository="test/repo",
+                    pr_number=1,
+                    base_sha="abc123",
+                    head_sha="def456",
+                    status="pending",
+                )
+                db_session.add(review)
+                # Don't manually commit - let the context manager do it
+
+            # Verify the data was committed by querying with a new session
+            async with async_sessionmaker(
+                bind=async_engine, class_=AsyncSession
+            )() as verify_session:
+                result = await verify_session.execute(text("SELECT COUNT(*) FROM reviews"))
+                count = result.scalar()
+                assert count == 1
+        finally:
+            session_module.reset_engine()
+
+    async def test_get_async_session_propagates_error(
+        self,
+        async_engine,
+    ) -> None:
+        from sqlalchemy.ext.asyncio import async_sessionmaker
+
+        from arbiter.db.models import ReviewModel
+
+        session_module._engine = async_engine
+        session_module._session_factory = async_sessionmaker(
+            bind=async_engine,
+            class_=AsyncSession,
+            expire_on_commit=False,
+        )
+
+        try:
+            # The error should be re-raised after rollback is called
+            with pytest.raises(ValueError, match="Test error"):
+                async for db_session in session_module.get_async_session():
+                    review = ReviewModel(
+                        repository="test/repo",
+                        pr_number=99,
+                        base_sha="abc123",
+                        head_sha="def456",
+                        status="pending",
+                    )
+                    db_session.add(review)
+                    raise ValueError("Test error")
+
+            # The session context manager handled the error correctly
+            # (exception was propagated, rollback was called internally)
+        finally:
+            session_module.reset_engine()
+
+    async def test_init_db_creates_tables(self, async_engine) -> None:
+        from sqlalchemy import text
+        from sqlalchemy.ext.asyncio import async_sessionmaker
+
+        # Set up the engine (tables already created by fixture, but let's verify)
+        session_module._engine = async_engine
+        session_module._session_factory = None
+
+        try:
+            # Call init_db
+            await session_module.init_db()
+
+            # Verify tables exist
+            async with async_sessionmaker(bind=async_engine, class_=AsyncSession)() as session:
+                # Try to query the reviews table
+                result = await session.execute(text("SELECT 1 FROM reviews LIMIT 1"))
+                # If no error, table exists
+                assert result is not None
+        finally:
+            session_module.reset_engine()
+
+    async def test_close_db_disposes_engine(self, async_engine) -> None:
+        session_module._engine = async_engine
+        session_module._session_factory = "not none"  # type: ignore
+
+        await session_module.close_db()
+
+        assert session_module._engine is None
+        assert session_module._session_factory is None
+
+    def test_session_factory_create(self) -> None:
+        # Reset to ensure clean state
+        session_module.reset_engine()
+
+        # This will fail without proper settings, so we just test the path
+        # where the factory already exists
+        session_module._session_factory = "mock_factory"  # type: ignore
+
+        result = session_module.async_session_factory()
+        assert result == "mock_factory"
+
+        session_module.reset_engine()