diff --git a/backend/tests/test_elements.py b/backend/tests/test_elements.py
new file mode 100644
index 0000000..573a0ee
--- /dev/null
+++ b/backend/tests/test_elements.py
@@ -0,0 +1,18 @@
+"""Test the elements API endpoints."""
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from app.main import app
+
+
+@pytest.mark.asyncio
+async def test_list_projects_returns_list():
+    """Projects endpoint returns a list."""
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.get("/api/projects")
+
+    assert response.status_code == 200
+    assert isinstance(response.json(), list)
+
diff --git a/backend/tests/test_health.py b/backend/tests/test_health.py
index fb28fc7..e3b795a 100644
--- a/backend/tests/test_health.py
+++ b/backend/tests/test_health.py
@@ -8,10 +8,10 @@ from app.main import app
 
 @pytest.mark.asyncio
 async def test_health_returns_ok():
+    """Health endpoint returns status ok."""
     transport = ASGITransport(app=app)
     async with AsyncClient(transport=transport, base_url="http://test") as client:
         response = await client.get("/health")
 
     assert response.status_code == 200
     assert response.json() == {"status": "ok"}
-
diff --git a/backend/tests/test_models.py b/backend/tests/test_models.py
new file mode 100644
index 0000000..e497ab7
--- /dev/null
+++ b/backend/tests/test_models.py
@@ -0,0 +1,46 @@
+"""Test database models and schema validation."""
+
+from app.schemas.element import ProjectOut, ElementOut, PropertyOut
+from uuid import uuid4
+
+
+def test_project_schema_validates():
+    """ProjectOut schema accepts valid data."""
+    data = {
+        "id": uuid4(),
+        "name": "Test Project",
+        "filename": "test.ifc",
+        "description": "A test",
+        "ifc_schema": "IFC4",
+        "element_count": 42,
+    }
+    project = ProjectOut(**data)
+    assert project.name == "Test Project"
+    assert project.element_count == 42
+
+
+def test_element_schema_validates():
+    """ElementOut schema accepts valid data."""
+    data = {
+        "id": uuid4(),
+        "global_id": "2XPyKWY018sA1ygZKgQPtU",
+        "ifc_type": "IfcWall",
+        "name": "Wall-1",
+        "description": "",
+        "storey": "Ground Floor",
+    }
+    element = ElementOut(**data)
+    assert element.ifc_type == "IfcWall"
+
+
+def test_property_schema_validates():
+    """PropertyOut schema accepts valid data."""
+    data = {
+        "id": uuid4(),
+        "pset_name": "Pset_WallCommon",
+        "name": "ThermalTransmittance",
+        "value": "1.5",
+    }
+    prop = PropertyOut(**data)
+    assert prop.pset_name == "Pset_WallCommon"
+
diff --git a/backend/tests/test_upload.py b/backend/tests/test_upload.py
new file mode 100644
index 0000000..49dc482
--- /dev/null
+++ b/backend/tests/test_upload.py
@@ -0,0 +1,34 @@
+"""Test the IFC upload endpoint."""
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from app.main import app
+
+
+@pytest.mark.asyncio
+async def test_upload_rejects_non_ifc():
+    """Upload endpoint rejects files without .ifc extension."""
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.post(
+            "/api/upload",
+            files={"file": ("model.obj", b"dummy content", "application/octet-stream")},
+        )
+
+    assert response.status_code == 400
+    assert "Only .ifc files" in response.json()["detail"]
+
+
+@pytest.mark.asyncio
+async def test_upload_rejects_empty_filename():
+    """Upload endpoint rejects files with wrong extension."""
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.post(
+            "/api/upload",
+            files={"file": ("readme.txt", b"not an ifc file", "text/plain")},
+        )
+
+    assert response.status_code == 400
+