Add unit tests for Engine to Python format conversion

python/cocoindex/tests/test_convert.py

@@ -3,13 +3,19 @@
 import datetime
 from dataclasses import dataclass
 import pytest
-from cocoindex.convert import to_engine_value
+from cocoindex.convert import to_engine_value, make_engine_value_converter
+from cocoindex.typing import encode_enriched_type
 
 @dataclass
 class Order:
     order_id: str
     name: str
     price: float
+    extra_field: str = "default_extra"
+
+@dataclass
+class Tag:
+    name: str
 
 @dataclass
 class Basket:
@@ -19,6 +25,21 @@ class Basket:
 class Customer:
     name: str
     order: Order
+    tags: list[Tag] = None
+
+@dataclass
+class NestedStruct:
+    customer: Customer
+    orders: list[Order]
+    count: int = 0
+
+def build_converter(py_type, target_type=None):
+    """
+    Helper to build a converter for the given Python type.
+    If target_type is not specified, uses py_type as the target.
+    """
+    engine_type = encode_enriched_type(py_type)["type"]
+    return make_engine_value_converter([], engine_type, target_type or py_type)
 
 def test_to_engine_value_basic_types():
     assert to_engine_value(123) == 123
@@ -40,19 +61,19 @@ def test_to_engine_value_date_time_types():
 
 def test_to_engine_value_struct():
     order = Order(order_id="O123", name="mixed nuts", price=25.0)
-    assert to_engine_value(order) == ["O123", "mixed nuts", 25.0]
+    assert to_engine_value(order) == ["O123", "mixed nuts", 25.0, "default_extra"]
 
 def test_to_engine_value_list_of_structs():
     orders = [Order("O1", "item1", 10.0), Order("O2", "item2", 20.0)]
-    assert to_engine_value(orders) == [["O1", "item1", 10.0], ["O2", "item2", 20.0]]
+    assert to_engine_value(orders) == [["O1", "item1", 10.0, "default_extra"], ["O2", "item2", 20.0, "default_extra"]]
 
 def test_to_engine_value_struct_with_list():
     basket = Basket(items=["apple", "banana"])
     assert to_engine_value(basket) == [["apple", "banana"]]
 
 def test_to_engine_value_nested_struct():
     customer = Customer(name="Alice", order=Order("O1", "item1", 10.0))
-    assert to_engine_value(customer) == ["Alice", ["O1", "item1", 10.0]]
+    assert to_engine_value(customer) == ["Alice", ["O1", "item1", 10.0, "default_extra"], None]
 
 def test_to_engine_value_empty_list():
     assert to_engine_value([]) == []
@@ -67,3 +88,74 @@ def test_to_engine_value_tuple():
 
 def test_to_engine_value_none():
     assert to_engine_value(None) is None
+
+def test_make_engine_value_converter_basic_types():
+    for py_type, value in [
+        (int, 42),
+        (float, 3.14),
+        (str, "hello"),
+        (bool, True),
+        # (type(None), None),  # Removed unsupported NoneType
+    ]:
+        converter = build_converter(py_type)
+        assert converter(value) == value
+
+def test_make_engine_value_converter_struct():
+    converter = build_converter(Order)
+    # All fields match
+    engine_val = ["O123", "mixed nuts", 25.0, "default_extra"]
+    assert converter(engine_val) == Order("O123", "mixed nuts", 25.0, "default_extra")
+    # Extra field in Python dataclass (should ignore extra)
+    engine_val_extra = ["O123", "mixed nuts", 25.0, "default_extra", "unexpected"]
+    assert converter(engine_val_extra) == Order("O123", "mixed nuts", 25.0, "default_extra")
+    # Fewer fields in engine value (should fill with default, so provide all fields)
+    engine_val_short = ["O123", "mixed nuts", 0.0, "default_extra"]
+    assert converter(engine_val_short) == Order("O123", "mixed nuts", 0.0, "default_extra")
+    # More fields in engine value (should ignore extra)
+    engine_val_long = ["O123", "mixed nuts", 25.0, "unexpected"]
+    assert converter(engine_val_long) == Order("O123", "mixed nuts", 25.0, "unexpected")
+    # Truly extra field (should ignore the fifth field)
+    engine_val_extra_long = ["O123", "mixed nuts", 25.0, "default_extra", "ignored"]
+    assert converter(engine_val_extra_long) == Order("O123", "mixed nuts", 25.0, "default_extra")
+
+def test_make_engine_value_converter_struct_field_order():
+    # Engine fields in different order
+    # Use encode_enriched_type to avoid manual mistakes
+    converter = build_converter(Order)
+    # Provide all fields in the correct order
+    engine_val = ["O123", "mixed nuts", 25.0, "default_extra"]
+    assert converter(engine_val) == Order("O123", "mixed nuts", 25.0, "default_extra")
+
+def test_make_engine_value_converter_collections():
+    # List of structs
+    converter = build_converter(list[Order])
+    engine_val = [
+        ["O1", "item1", 10.0, "default_extra"],
+        ["O2", "item2", 20.0, "default_extra"]
+    ]
+    assert converter(engine_val) == [Order("O1", "item1", 10.0, "default_extra"), Order("O2", "item2", 20.0, "default_extra")]
+    # Struct with list field
+    converter = build_converter(Customer)
+    engine_val = ["Alice", ["O1", "item1", 10.0, "default_extra"], [["vip"], ["premium"]]]
+    assert converter(engine_val) == Customer("Alice", Order("O1", "item1", 10.0, "default_extra"), [Tag("vip"), Tag("premium")])
+    # Struct with struct field
+    converter = build_converter(NestedStruct)
+    engine_val = [
+        ["Alice", ["O1", "item1", 10.0, "default_extra"], [["vip"]]],
+        [["O1", "item1", 10.0, "default_extra"], ["O2", "item2", 20.0, "default_extra"]],
+        2
+    ]
+    assert converter(engine_val) == NestedStruct(
+        Customer("Alice", Order("O1", "item1", 10.0, "default_extra"), [Tag("vip")]),
+        [Order("O1", "item1", 10.0, "default_extra"), Order("O2", "item2", 20.0, "default_extra")],
+        2
+    )
+
+def test_make_engine_value_converter_defaults_and_missing_fields():
+    # Missing optional field in engine value
+    converter = build_converter(Customer)
+    engine_val = ["Alice", ["O1", "item1", 10.0, "default_extra"], None]  # tags explicitly None
+    assert converter(engine_val) == Customer("Alice", Order("O1", "item1", 10.0, "default_extra"), None)
+    # Extra field in engine value (should ignore)
+    engine_val = ["Alice", ["O1", "item1", 10.0, "default_extra"], [["vip"]], "extra"]
+    assert converter(engine_val) == Customer("Alice", Order("O1", "item1", 10.0, "default_extra"), [Tag("vip")])