QA and Testing — Questions¶

This file tracks big-picture, cross-module questions about QA and Testing. For questions specific to a single module, use that module's QUESTIONS.md instead.

How to Use This File¶

1. Write questions immediately — when something is confusing, log it here before moving on.
2. Be specific — "I don't understand mocking" is less useful than "When should I use a mock vs. a stub vs. a fake?"
3. Update status as you find answers — partial answers count.
4. Link your answers to the module or resource where you found the explanation.
5. Add follow-up questions — good answers often raise better questions.

Status Legend¶

Question Format¶

### Q{{N}}: {{QUESTION_TITLE}}

**Asked:** {{YYYY-MM-DD}}
**Status:** 🔴 Unanswered

**Full question:**
Write the question in full. Include context about what prompted it.

**My current hypothesis:**
What do you think the answer might be, even if you're not sure?

**Answer:**
_To be filled in_

**Source:**
_Where did you find/confirm the answer?_

**Follow-up questions:**
- _Any new questions this answer raised_

Questions¶

Q001: When does testing slow down development vs. speed it up?¶

Asked: 2026-06-09 Status: 🟡 Partial

Full question: I keep hearing that testing saves time, but writing tests also takes time. When does investing in tests pay off, and when is it overkill? Are there situations where testing slows a team down permanently?

My current hypothesis: Testing probably pays off when the codebase is large and long-lived, but might be overkill for small scripts or throwaway prototypes. Not sure about the inflection point.

Answer: Research in progress. See Module 07 (TDD) and Module 11 (QA Strategy) for framework.

Source: To be filled in

Follow-up questions: - How do I measure the ROI of testing on an existing project? - What does "good enough" testing look like for a startup vs. an enterprise?

Q002: What is the most common mistake teams make with automated testing?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: I want to understand the pitfalls before developing bad habits. What do experienced QA engineers and developers wish they'd known earlier about automated testing?

My current hypothesis: Based on what I've heard, it might be over-relying on end-to-end tests (slow, flaky) or having tests that test implementation details instead of behavior.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - How do I recognize "testing the implementation" in my own code? - What does a healthy test suite look like vs. one that's technically high-coverage but still low-value?

Q003: How does QA and Testing relate to type systems and formal verification?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: TypeScript and Rust's type systems catch entire categories of bugs at compile time. Does this reduce the need for unit tests? How do testing and type systems complement each other?

My current hypothesis: Type systems and tests seem to catch different kinds of bugs — types catch structural/type-related bugs, tests catch behavioral/logic bugs. But I'm not sure where the boundary is.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - Is there a point at which a sufficiently strong type system makes unit tests redundant? - What does property-based testing (Hypothesis, fast-check) add beyond example-based tests?

Add new questions above this line. Keep them numbered sequentially.

Resolved Questions Archive¶

Move fully answered questions (🟢) here to keep the active list manageable.

(none yet)

Question Stats¶