b4w data factories and tests

src/models.py

@@ -4,7 +4,7 @@ from datetime import date
 from decimal import Decimal
 from enum import Enum
 
-from pydantic import BaseModel, Field, ValidationError, field_validator
+from pydantic import BaseModel, Field, field_validator
 
 IBAN_PATTERN = r"^[A-Z]{2}\d{2}[A-Z0-9]{11,30}$"
 
@@ -57,12 +57,16 @@ class B4wExport(BaseModel):
 
     @field_validator("category", mode="before")
     @classmethod
-    def category_str_is_parsable(cls, category_str: str) -> Category | None:
-        category = Category.from_str(category_str)
-        assert category
-        category_str_2 = category.to_str()
-        if not category_str == category_str_2:
-            raise ValidationError(f"Category string cannot be parsed: {category_str}")
+    def category_str_is_parsable(
+        cls, category_in: str | Category | None
+    ) -> Category | None:
+        if category_in is None or category_in == "":
+            return None
+        if isinstance(category_in, Category):
+            return category_in
+        category = Category.from_str(category_in)
+        if category is None or category.to_str() != category_in:
+            raise ValueError(f"Category string cannot be parsed: {category_in!r}")
         return category