Find Edge Cases on Purpose

A normal example shows that a program works somewhere comfortable. An edge case checks a value near the limit of a rule.

The quiz plan requires every title, prompt, and expected answer to contain some usable text:

def has_usable_text(text):
    return len(text.strip()) > 0

Testing "Ocean Facts" is useful, but it cannot reveal whether the function handles empty or padded text. Give those edges a turn too:

assert has_usable_text("") is False
assert has_usable_text("   ") is False
assert has_usable_text("?") is True

The one-character case matters because the requirement says non-empty, not “at least two characters.”

Common places to look

For the quiz engine, edge cases often live at:

• exactly three questions, the minimum valid plan;

• zero correct answers or a perfect score;

• an empty string, list, or dictionary;

• text containing only spaces;

• a one-character prompt or answer;

• two prompts that match after cleaning;

• an answer with spaces or different capitalization.

Do not add all of these blindly. Choose cases that can change the behavior promised by the requirements.

Boundary tables expose gaps

For a text rule, write a small table before code:

The table makes the boundary visible: after cleaning, zero characters is unusable and one character is usable.

Test data should have a reason

Each test case should answer a question:

• Does whitespace-only text count as empty?

• Is the shortest non-empty prompt accepted?

• Does cleaning preserve ordinary text?

Random values may shake the box, but a deliberate boundary case tells you exactly which hinge you are testing.