What would you test in unit tests for an address normalization function?

What would you test in unit tests for an address normalization function?

• A. Diacritic removal
• B. Abbreviation mapping
• C. Casing
• D. All of the above

Answer: (D)

Address normalization is a multi-step process that aims to produce a single, comparable form from many possible inputs. To test it effectively, you need to cover diacritic removal, abbreviation mapping, and casing, because each handles a different kind of variation. Diacritics like é or ü may appear in street names; confirming that those characters are stripped to their base letters ensures comparisons don’t fail due to accents. Abbreviation mapping deals with short forms such as St., Ave., or Blvd., so inputs like "123 St" and "123 Street" end up in the same canonical form. Casing variations—from all lower to all upper or mixed case—must be normalized to one consistent case so case-insensitive matches succeed. Since the normalization pipeline typically combines these steps, testing only one aspect leaves other variations unchecked. Therefore, testing all of the above ensures the function reliably produces a consistent, comparable result across real-world inputs.