Initial Claude implementation of list mode

From https://github.com/simonw/research/tree/main/sqlite-utils-iterator-support

I made very minor changes to the test (removing a sys.path insert)

Refs #672

Refs https://github.com/simonw/research/pull/31

tests/test_list_mode.py

@@ -0,0 +1,175 @@
+"""
+Tests for list-based iteration in insert_all and upsert_all
+"""
+import pytest
+from sqlite_utils import Database
+
+
+def test_insert_all_list_mode_basic():
+    """Test basic insert_all with list-based iteration"""
+    db = Database(memory=True)
+
+    def data_generator():
+        # First yield column names
+        yield ["id", "name", "age"]
+        # Then yield data rows
+        yield [1, "Alice", 30]
+        yield [2, "Bob", 25]
+        yield [3, "Charlie", 35]
+
+    db["people"].insert_all(data_generator())
+
+    rows = list(db["people"].rows)
+    assert len(rows) == 3
+    assert rows[0] == {"id": 1, "name": "Alice", "age": 30}
+    assert rows[1] == {"id": 2, "name": "Bob", "age": 25}
+    assert rows[2] == {"id": 3, "name": "Charlie", "age": 35}
+
+
+def test_insert_all_list_mode_with_pk():
+    """Test insert_all with list mode and primary key"""
+    db = Database(memory=True)
+
+    def data_generator():
+        yield ["id", "name", "score"]
+        yield [1, "Alice", 95]
+        yield [2, "Bob", 87]
+
+    db["scores"].insert_all(data_generator(), pk="id")
+
+    assert db["scores"].pks == ["id"]
+    rows = list(db["scores"].rows)
+    assert len(rows) == 2
+
+
+def test_upsert_all_list_mode():
+    """Test upsert_all with list-based iteration"""
+    db = Database(memory=True)
+
+    # Initial insert
+    def initial_data():
+        yield ["id", "name", "value"]
+        yield [1, "Alice", 100]
+        yield [2, "Bob", 200]
+
+    db["data"].insert_all(initial_data(), pk="id")
+
+    # Upsert with some updates and new records
+    def upsert_data():
+        yield ["id", "name", "value"]
+        yield [1, "Alice", 150]  # Update existing
+        yield [3, "Charlie", 300]  # Insert new
+
+    db["data"].upsert_all(upsert_data(), pk="id")
+
+    rows = list(db["data"].rows_where(order_by="id"))
+    assert len(rows) == 3
+    assert rows[0] == {"id": 1, "name": "Alice", "value": 150}
+    assert rows[1] == {"id": 2, "name": "Bob", "value": 200}
+    assert rows[2] == {"id": 3, "name": "Charlie", "value": 300}
+
+
+def test_list_mode_with_various_types():
+    """Test list mode with different data types"""
+    db = Database(memory=True)
+
+    def data_generator():
+        yield ["id", "name", "score", "active"]
+        yield [1, "Alice", 95.5, True]
+        yield [2, "Bob", 87.3, False]
+        yield [3, "Charlie", None, True]
+
+    db["mixed"].insert_all(data_generator())
+
+    rows = list(db["mixed"].rows)
+    assert len(rows) == 3
+    assert rows[0]["score"] == 95.5
+    assert rows[1]["active"] == 0  # SQLite stores boolean as int
+    assert rows[2]["score"] is None
+
+
+def test_list_mode_error_non_string_columns():
+    """Test that non-string column names raise an error"""
+    db = Database(memory=True)
+
+    def bad_data():
+        yield [1, 2, 3]  # Non-string column names
+        yield ["a", "b", "c"]
+
+    with pytest.raises(ValueError, match="must be a list of column name strings"):
+        db["bad"].insert_all(bad_data())
+
+
+def test_list_mode_error_mixed_types():
+    """Test that mixing list and dict raises an error"""
+    db = Database(memory=True)
+
+    def bad_data():
+        yield ["id", "name"]
+        yield {"id": 1, "name": "Alice"}  # Should be a list, not dict
+
+    with pytest.raises(ValueError, match="must also be lists"):
+        db["bad"].insert_all(bad_data())
+
+
+def test_list_mode_empty_after_headers():
+    """Test that only headers without data works gracefully"""
+    db = Database(memory=True)
+
+    def data_generator():
+        yield ["id", "name", "age"]
+        # No data rows
+
+    result = db["people"].insert_all(data_generator())
+    assert result is not None
+    assert not db["people"].exists()
+
+
+def test_list_mode_batch_processing():
+    """Test list mode with large dataset requiring batching"""
+    db = Database(memory=True)
+
+    def large_data():
+        yield ["id", "value"]
+        for i in range(1000):
+            yield [i, f"value_{i}"]
+
+    db["large"].insert_all(large_data(), batch_size=100)
+
+    count = db.execute("SELECT COUNT(*) as c FROM large").fetchone()[0]
+    assert count == 1000
+
+
+def test_list_mode_shorter_rows():
+    """Test that rows shorter than column list get NULL values"""
+    db = Database(memory=True)
+
+    def data_generator():
+        yield ["id", "name", "age", "city"]
+        yield [1, "Alice", 30, "NYC"]
+        yield [2, "Bob"]  # Missing age and city
+        yield [3, "Charlie", 35]  # Missing city
+
+    db["people"].insert_all(data_generator())
+
+    rows = list(db["people"].rows_where(order_by="id"))
+    assert rows[0] == {"id": 1, "name": "Alice", "age": 30, "city": "NYC"}
+    assert rows[1] == {"id": 2, "name": "Bob", "age": None, "city": None}
+    assert rows[2] == {"id": 3, "name": "Charlie", "age": 35, "city": None}
+
+
+def test_backwards_compatibility_dict_mode():
+    """Ensure dict mode still works (backward compatibility)"""
+    db = Database(memory=True)
+
+    # Traditional dict-based insert
+    data = [
+        {"id": 1, "name": "Alice", "age": 30},
+        {"id": 2, "name": "Bob", "age": 25},
+    ]
+
+    db["people"].insert_all(data)
+
+    rows = list(db["people"].rows)
+    assert len(rows) == 2
+    assert rows[0] == {"id": 1, "name": "Alice", "age": 30}