Write Unit Tests for Given Code

Write unit tests for a given piece of code.

Asked in the Onsite skills test stage. Part of the Java skills test alongside design patterns theory and a simple tree question.

Test the following function using a standard unit-testing framework. Cover normal behavior, the \$100 threshold, priority handling, and invalid negative amounts.

def calculate_fee(amount, is_priority):
    if amount < 0:
        raise ValueError("amount cannot be negative")
    fee = 0 if amount >= 100 else 5
    if is_priority:
        fee += 10
    return fee

Your tests should assert returned values and verify that negative amounts raise ValueError. Include boundary and representative cases.