added asins to build_product_details

tests/test_build_product_details.py

@@ -78,6 +78,17 @@ def test_promo_fields_read_through():
     assert product.metadata.percentage == 20
 
 
+def test_asin_reads_through():
+    """asin round-trips: convert_product_to_mongo writes it, so the consumer
+    must read it back for the SellerAmp lookup"""
+    product = build_product_details(_doc(asin="B0CHX3QBCH"), min_percentage=0)
+    assert product.metadata.asin == "B0CHX3QBCH"
+
+
+def test_missing_asin_defaults_to_none():
+    assert build_product_details(_doc(), min_percentage=0).metadata.asin is None
+
+
 def test_missing_promo_keys_default_to_none():
     """a doc from a lagging monitor lacks promo keys -> None, not KeyError"""
     product = build_product_details(_doc(), min_percentage=0)