Generate Jest Unit Tests for a Pure Function

Ask Copilot to create Jest tests covering normal and edge cases for a pure function.

category:testing

jest

unit-tests

javascript

Prompt

Write Jest unit tests for the following pure function.
  
  Requirements:
  - Cover common cases and edge cases.
  - Include tests for invalid input or error scenarios if relevant.
  - Use clear test names that describe behaviour.
  
  Function:
  
  [Paste function here]