The Full Stack AI #4

Practical AI for full-stack developers

Why this matters

AI is very good at generating tests.

That doesn’t mean those tests are good.

Many teams now have:

• more tests
• higher coverage
• less confidence

This issue is about using AI to challenge assumptions, not blindly increase test count.

🧠 AI Technique of the Week

Use AI as an adversary, not an assistant

Most developers ask AI:

“Write tests for this code.”

That produces tests that:

• mirror the implementation
• repeat the same assumptions
• miss real-world failures

Instead, make the AI try to break your code.

The approach

Treat AI like a malicious or careless user.

Prompt I use:

You are trying to break this function.

1. Identify assumptions the code makes
2. Propose inputs that violate those assumptions
3. Suggest test cases that would expose failures
4. Focus on edge cases and misuse, not happy paths

        

This produces fewer tests — but much better ones.

🛠 Tool / Workflow Spotlight

AI + existing tests (gap analysis)

Instead of asking for new tests immediately:

1. Give AI:
2. Ask:

Follow-up prompt:

Given this code and these tests:
- Identify gaps in coverage
- Highlight risky untested behaviour
- Suggest tests that would add confidence

        

This avoids redundant tests and false security.

⚡ Prompt you can steal

False-confidence detector

Review these tests and identify:
- What assumptions they rely on
- What real-world scenarios they miss
- Where failures would still occur

        

Use this before:

• merging AI-generated tests
• trusting coverage numbers
• refactoring with confidence

🔍 AI news

• AI-generated tests increase coverage faster than confidence → Coverage is a metric, not a guarantee.
• Teams are shifting from quantity to test intent → Fewer, better tests outperform massive suites.

💼 Career insight

Developers who understand testing get trusted

Teams trust developers who:

• know what not to test
• understand failure modes
• design tests around behaviour, not code

AI doesn’t remove this skill — it makes it visible.

What’s next

Next issue:

• Using AI for API development
• Safer request/response design
• Avoiding AI-generated contract drift

Thanks for reading. New issues arrive weekly.

— The Full Stack AI