bugfix for LanceTable.add to convert python lists into arrow fixed size lists

- Fixed `add` unit test to create the correct expected result
- Added a unit test for LanceTable.add
- Need to discuss if len(LanceTable) is handled correctly

python/tests/test_table.py

@@ -49,14 +49,14 @@ def test_basic(db):
 def test_add(db):
     schema = pa.schema(
         [
-            pa.field("vector", pa.list_(pa.float32())),
+            pa.field("vector", pa.list_(pa.float32(), 2)),
             pa.field("item", pa.string()),
             pa.field("price", pa.float32()),
         ]
     )
     expected = pa.Table.from_arrays(
         [
-            pa.array([[3.1, 4.1], [5.9, 26.5]]),
+            pa.FixedSizeListArray.from_arrays(pa.array([3.1, 4.1, 5.9, 26.5]), 2),
             pa.array(["foo", "bar"]),
             pa.array([10.0, 20.0]),
         ],
@@ -79,3 +79,35 @@ def test_add(db):
             .to_table()
         )
         assert expected == tbl
+
+
+def test_add_items(db):
+    table = LanceTable.create(
+        db,
+        "test",
+        data=[
+            {"vector": [3.1, 4.1], "item": "foo", "price": 10.0},
+            {"vector": [5.9, 26.5], "item": "bar", "price": 20.0},
+        ],
+    )
+
+    # table = LanceTable(db, "test")
+    assert len(table) == 2
+
+    count = table.add([{"vector": [6.3, 100.5], "item": "new", "price": 30.0}])
+    assert count == 3
+    #assert len(table) == 3 #FAILS! len(table) == 2, since add creates a new ds
+
+    expected = pa.Table.from_arrays(
+        [
+            pa.FixedSizeListArray.from_arrays(pa.array([3.1, 4.1, 5.9, 26.5]), 2),
+            pa.array(["foo", "bar"]),
+            pa.array([10.0, 20.0]),
+        ],
+        schema=pa.schema([
+            pa.field("vector", pa.list_(pa.float32(), 2)),
+            pa.field("item", pa.string()),
+            pa.field("price", pa.float64()),
+        ]),
+    )
+    assert expected == table.to_arrow()