test: add API endpoint test suite and enable the CI test job

.github/workflows/release.yml

@@ -89,63 +89,11 @@ jobs:
         python -m pip install --upgrade pip
         pip install -c backend/constraints-${{ matrix.lancedb }}.txt \
           -r backend/requirements.txt
-        pip install httpx  # Required for TestClient
+        # httpx is required by TestClient; <0.28 keeps the app= kwarg
+        # that the starlette version pinned by fastapi 0.104 still uses
+        pip install pytest "httpx<0.28"
 
-    - name: Debug dependency versions
+    - name: Run API endpoint tests
       run: |
         cd backend
-        python -c "
-        import lancedb
-        import pyarrow
-        import fastapi
-        import starlette
-        from fastapi.testclient import TestClient
-        import inspect
-
-        print(f'=== Lance {lancedb.__version__} Dependencies ===')
-        print(f'LanceDB: {lancedb.__version__}')
-        print(f'PyArrow: {pyarrow.__version__}')
-        print(f'FastAPI: {fastapi.__version__}')
-        print(f'Starlette: {starlette.__version__}')
-
-        print(f'\\n=== TestClient signature ===')
-        sig = inspect.signature(TestClient.__init__)
-        print(f'TestClient.__init__{sig}')
-
-        print(f'\\n=== App module structure ===')
-        import app
-        print(f'app module type: {type(app)}')
-        if hasattr(app, 'app'):
-            print(f'app.app type: {type(app.app)}')
-            print(f'app.app class: {app.app.__class__.__name__}')
-        else:
-            print('No app.app attribute found')
-        "
-
-    - name: Test API endpoints
-      run: |
-        cd backend
-        python -c "
-        import app
-        import lancedb
-        import pyarrow
-        from fastapi.testclient import TestClient
-
-        # Print version information first
-        print(f'Testing with LanceDB {lancedb.__version__}, PyArrow {pyarrow.__version__}')
-
-        # Test health endpoint only - skip TestClient for now
-        # response = client.get('/healthz')
-        # assert response.status_code == 200
-        # assert response.json()['ok'] == True
-        print('✓ Health check skipped (debugging TestClient)')
-
-        # Test datasets endpoint (will fail without data but should not crash)
-        # try:
-        #     response = client.get('/datasets')
-        #     print('✓ Datasets endpoint accessible')
-        # except Exception as e:
-        #     print(f'✓ Datasets endpoint handled error gracefully: {e}')
-
-        print('✓ Debug completed - TestClient investigation needed')
-        "
+        python -m pytest tests/ -v

CHANGELOG.md

@@ -7,8 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- API endpoint test suite (pytest + FastAPI TestClient) covering all six endpoints, pagination, column filtering, value serialization, and corrupted-dataset handling. The CI test job now runs it against every supported Lance version (#28).
+
 ### Fixed
 - Frontend fetch calls now check `response.ok` before parsing JSON, so HTTP error responses surface as error states instead of being parsed as data (#27).
+- `/rows` with unknown column names and `/vector/preview` with a missing or non-vector column now return 400 as intended; the error was previously masked as a generic 500 (#28).
 
 ## [0.2.0] - 2026-04-16
 

backend/app.py

@@ -341,6 +341,8 @@ async def get_dataset_rows(
             "offset": offset
         }
 
+    except HTTPException:
+        raise
     except Exception as e:
         logger.error(f"Error getting rows for {dataset_name}: {e}")
         raise HTTPException(status_code=500, detail="Failed to get dataset rows")
@@ -392,6 +394,8 @@ async def get_vector_preview(
 
         return {"stats": stats, "preview": preview}
 
+    except HTTPException:
+        raise
     except Exception as e:
         logger.error(f"Error getting vector preview for {dataset_name}.{column}: {e}")
         raise HTTPException(status_code=500, detail="Failed to get vector preview")

backend/tests/conftest.py

@@ -0,0 +1,84 @@
+"""Shared fixtures: a temporary Lance database and a FastAPI test client.
+
+Run from the backend directory:
+
+    python -m pytest tests/ -v
+
+The sample data is written once per session with whatever lancedb/pyarrow
+versions are installed, so the same tests run against every constraints file.
+"""
+
+import os
+import sys
+from pathlib import Path
+
+import lancedb
+import pyarrow as pa
+import pytest
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+ROWS = 10
+VEC_DIM = 4
+CLIP_DIM = 512
+
+
+def _sample_table() -> pa.Table:
+    ids = list(range(ROWS))
+    texts = [None if i == 3 else f"row {i}" for i in ids]
+    scores = [i * 1.5 for i in ids]
+    blobs = [b"hello" if i % 2 == 0 else b"\xff\xfe\x01\x02" for i in ids]
+    vecs = [None if i == 5 else [float(i), -1.0, 0.5, 2.0] for i in ids]
+    unit = 1.0 / CLIP_DIM ** 0.5
+    embeddings = [[unit] * CLIP_DIM for _ in ids]
+
+    return pa.table({
+        "id": pa.array(ids, type=pa.int64()),
+        "text": pa.array(texts, type=pa.string()),
+        "score": pa.array(scores, type=pa.float64()),
+        "blob": pa.array(blobs, type=pa.binary()),
+        "vec": pa.array(vecs, type=pa.list_(pa.float32())),
+        "embedding": pa.array(embeddings, type=pa.list_(pa.float32(), CLIP_DIM)),
+    })
+
+
+def _corrupt_table(db_dir: Path, name: str) -> None:
+    """Overwrite the data fragments of a table so reads fail but the
+    manifest stays intact and open_table() still succeeds."""
+    table_dir = db_dir / f"{name}.lance"
+    data_files = [p for p in table_dir.rglob("*.lance") if p.is_file()]
+    assert data_files, f"no data files found under {table_dir}"
+    for path in data_files:
+        path.write_bytes(b"not a lance data file")
+
+
+@pytest.fixture(scope="session")
+def data_dir(tmp_path_factory):
+    path = tmp_path_factory.mktemp("lance-data")
+    db = lancedb.connect(str(path))
+    db.create_table("sample", _sample_table())
+    db.create_table("broken", pa.table({"id": pa.array([1, 2, 3], type=pa.int64())}))
+    _corrupt_table(path, "broken")
+    return path
+
+
+@pytest.fixture(scope="session")
+def vec_nulls_preserved(data_dir):
+    """Lance format v1 (lancedb 0.3.x/0.5) stores a null list as an empty
+    list. Detect what the installed version actually does so tests can
+    assert the matching serialization."""
+    db = lancedb.connect(str(data_dir))
+    values = db.open_table("sample").to_arrow().column("vec").to_pylist()
+    return values[5] is None
+
+
+@pytest.fixture(scope="session")
+def client(data_dir):
+    # DATA_PATH is read at import time, so set it before importing app
+    os.environ["DATA_PATH"] = str(data_dir)
+    import app as app_module
+    app_module.DATA_PATH = data_dir
+
+    from fastapi.testclient import TestClient
+    with TestClient(app_module.app) as test_client:
+        yield test_client