implement preceding_pf_ids attribute on product footprint class

pathfinder_framework/product_footprint/product_footprint.py

@@ -34,6 +34,7 @@ class ProductFootprint:
         comment (str): A comment about the ProductFootprint.
         extensions (list[DataModelExtension]): A list of DataModelExtension objects.
         pcf (CarbonFootprint): The carbon footprint of the given product with value conforming to the data type CarbonFootprint.
+        preceding_pf_ids (list[ProductFootprintId]): A list of preceding ProductFootprintIds.
     """
 
     def __init__(
@@ -56,6 +57,7 @@ def __init__(
         comment: str,
         extensions: list[DataModelExtension],
         pcf: CarbonFootprint,
+        preceding_pf_ids: list[ProductFootprintId] | None = None,
     ):
         """
         Initializes a new ProductFootprint instance.
@@ -78,6 +80,7 @@ def __init__(
             comment (str): A comment about the ProductFootprint.
             extensions (list[DataModelExtension]): A list of DataModelExtension objects.
             pcf (CarbonFootprint): The carbon footprint of the given product with value conforming to the data type CarbonFootprint.
+            preceding_pf_ids (list[ProductFootprintId] | None): A list of preceding ProductFootprintIds.
         """
 
         if not isinstance(pcf, CarbonFootprint):
@@ -123,6 +126,14 @@ def __init__(
         if not isinstance(pcf, CarbonFootprint):
             raise ValueError("pcf must be an instance of CarbonFootprint")
 
+        if preceding_pf_ids is not None:
+            if not isinstance(preceding_pf_ids, list) or not all(
+                isinstance(pf_id, ProductFootprintId) for pf_id in preceding_pf_ids
+            ):
+                raise ValueError("preceding_pf_ids must be a list of ProductFootprintId")
+            if len(preceding_pf_ids) != len(set(preceding_pf_ids)):
+                raise ValueError("preceding_pf_ids must not contain duplicates")
+
         self.id = id if id else ProductFootprintId()
         self.spec_version = spec_version
         self.version = version
@@ -140,6 +151,7 @@ def __init__(
         self.comment = comment
         self.extensions = extensions
         self.pcf = pcf
+        self.preceding_pf_ids = preceding_pf_ids
 
     def __repr__(self) -> str:
         """Returns a string representation of the ProductFootprint instance."""

tests/product_footprint/test_product_footprint.py

@@ -151,6 +151,7 @@ def valid_product_footprint_data(valid_carbon_footprint_data):
         "comment": "This is a comment",
         "extensions": extensions,
         "pcf": CarbonFootprint(**valid_carbon_footprint_data),
+        "preceding_pf_ids": [ProductFootprintId(), ProductFootprintId()],
     }
 
 
@@ -180,6 +181,10 @@ def test_product_footprint_initialization(valid_product_footprint_data):
         isinstance(ext, DataModelExtension) for ext in product_footprint.extensions
     )
     assert isinstance(product_footprint.pcf, CarbonFootprint)
+    assert isinstance(product_footprint.preceding_pf_ids, list)
+    assert all(
+        isinstance(pf_id, ProductFootprintId) for pf_id in product_footprint.preceding_pf_ids
+    )
 
 
 def test_product_footprint_spec_version(valid_product_footprint_data):
@@ -585,3 +590,51 @@ def test_product_footprint_invalid_pcf(valid_product_footprint_data, pcf):
     invalid_product_footprint_data = {**valid_product_footprint_data, "pcf": pcf}
     with pytest.raises(ValueError, match="pcf must be an instance of CarbonFootprint"):
         ProductFootprint(**invalid_product_footprint_data)
+
+
+@pytest.mark.parametrize(
+    "preceding_pf_ids",
+    [
+        [ProductFootprintId(), ProductFootprintId()],  # list with multiple items
+        [],  # empty list
+    ],
+)
+def test_product_footprint_preceding_pf_ids(valid_product_footprint_data, preceding_pf_ids):
+    product_footprint_data = {
+        **valid_product_footprint_data,
+        "preceding_pf_ids": preceding_pf_ids,
+    }
+    product_footprint = ProductFootprint(**product_footprint_data)
+    assert len(product_footprint.preceding_pf_ids) == len(preceding_pf_ids)
+    for pf_id in product_footprint.preceding_pf_ids:
+        assert isinstance(pf_id, ProductFootprintId)
+
+
+@pytest.mark.parametrize(
+    "preceding_pf_ids",
+    [
+        123,
+        1.0,
+        "string",
+        {},
+        ProductFootprintId(),
+    ],
+)
+def test_product_footprint_invalid_preceding_pf_ids(valid_product_footprint_data, preceding_pf_ids):
+    invalid_product_footprint_data = {
+        **valid_product_footprint_data,
+        "preceding_pf_ids": preceding_pf_ids,
+    }
+    with pytest.raises(ValueError, match="preceding_pf_ids must be a list of ProductFootprintId"):
+        ProductFootprint(**invalid_product_footprint_data)
+
+
+def test_product_footprint_duplicate_preceding_pf_ids(valid_product_footprint_data):
+    pf_id = ProductFootprintId()
+    preceding_pf_ids = [pf_id, pf_id]
+    product_footprint_data = {
+        **valid_product_footprint_data,
+        "preceding_pf_ids": preceding_pf_ids,
+    }
+    with pytest.raises(ValueError, match="preceding_pf_ids must not contain duplicates"):
+        ProductFootprint(**product_footprint_data)