fix column param default and tests

api/app/routers/grid.py

@@ -24,7 +24,12 @@
     responses={200: {"description": "Get a grid tile"}, 404: {"description": "Not found"}},
     response_model=None,
 )
-async def grid_tile(tile_index: str, columns: list[str] = Query()) -> Response:
+async def grid_tile(
+    tile_index: str,
+    columns: list[str] = Query(
+        [], description="Colum/s to include in the tile. If empty, it returns only the cell index."
+    ),
+) -> Response:
     """Request a tile of h3 cells filtered by columns"""
     try:
         z = h3.api.basic_str.h3_get_resolution(tile_index)

api/tests/test_grid.py

@@ -8,7 +8,9 @@
 
 
 def test_grid_tile(grid_dataset):
-    response = test_client.get(f"/grid/tile/{grid_dataset}", headers=HEADERS)
+    response = test_client.get(
+        f"/grid/tile/{grid_dataset}", params={"columns": ["landcover", "population"]}, headers=HEADERS
+    )
 
     assert response.status_code == 200
     assert pl.read_ipc(response.read()).to_dict(as_series=False) == {
@@ -24,6 +26,21 @@ def test_grid_tile(grid_dataset):
     }
 
 
+def test_grid_tile_empty_column_param(grid_dataset):
+    response = test_client.get(f"/grid/tile/{grid_dataset}", headers=HEADERS)
+
+    assert response.status_code == 200
+    assert pl.read_ipc(response.read()).to_dict(as_series=False) == {
+        "cell": [
+            618668968382824400,
+            619428375900454900,
+            619428407452893200,
+            619428407943888900,
+            619428407676764200,
+        ],
+    }
+
+
 def test_grid_tile_404(grid_dataset):
     response = test_client.get("/grid/tile/8439181ffffffff", headers=HEADERS)