Testing, Safety and Demo Day

Step 1: Check what comes in

Your app will meet users who type things you never imagined: nothing at all, a whole paragraph, a single symbol. Validation checks input before using it.

def check_word(word):
    word = word.strip()
    if not word:
        return None, "Please type a word."
    if len(word) > 40:
        return None, "That's too long. Please use a shorter word."
    return word, None

for test in ["gravity", "   ", "x" * 50]:
    cleaned, problem = check_word(test)
    print(repr(test[:12]), "->", cleaned if cleaned else problem)

'gravity' -> gravity
'   ' -> Please type a word.
'xxxxxxxxxxxx' -> That's too long. Please use a shorter word.

The function returns two things: the cleaned word, or a friendly message about the problem.

Step 2: Be honest about AI

People should know when they are reading something an AI wrote, and that it can be wrong. Add a short line to every answer.

def show_answer(text):
    print(text)
    print("AI-generated. Check important facts.")

show_answer("Gravity is the pull that makes things fall.")

Gravity is the pull that makes things fall.
AI-generated. Check important facts.

Other guardrails you can add:

• A list of topics your app will and won’t help with.
• A rule that the app doesn’t store names or other personal data.
• A fallback message when the model fails.

Step 3: Test with real people

You know how your app is supposed to work, so you can’t see where it confuses people. A user test shows you.

1. Ask someone who hasn’t seen your app to try it.
2. Give them a goal (“find out what photosynthesis means”) and say nothing else.
3. Watch and take notes. Where did they pause? What did they type that you didn’t expect?
4. Don’t explain. If they get stuck, that’s the finding.
5. Thank them and ask: What was confusing? What would you change?

Step 4: Fix, then fix again

After two or three tests, you’ll see the same problems repeat. Fix the biggest one first. Then test again with someone new.

Step 5: Responsibilities of a builder

You are now someone who builds software that others rely on. Three habits will serve you well:

1. Honesty. Say what your app is, that AI is involved, and what it can’t do.
2. Safety. Expect mistakes and misuse. Add checks, and don’t ship what you wouldn’t want a younger sibling to use.
3. Privacy. Collect only what you need, and never share people’s information.

For Demo Day, present your app in two minutes: the problem you solved, a live demo, one problem you found in testing, and one thing you’d do next. Whatever you build next, you now know how.