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Agentic Engineering

Quality & Documentation

Testing and documentation are high-value agent use cases. Tests are self-validating—you immediately know if they work. Documentation is perpetually under-maintained—agents reduce the friction dramatically.

Testing

Section titled “Testing”

Where agents excel

Section titled “Where agents excel”

Unit test generation — Given a function, agents generate comprehensive tests: happy path, edge cases (null, empty, boundaries), error conditions. This is probably the single highest-ROI application for most teams.

Test case discovery — “What test cases should I consider for this function? Focus on edge cases and error conditions.” You’ll often find cases you hadn’t considered.

Mock and fixture generation — Test data structures, mock implementations, factory functions. Tedious setup is perfect for agents.

Regression tests — “Create a test that would have caught this bug: [describe bug]“

What to watch for

Section titled “What to watch for”
  • Tests that pass for wrong reasons — Tests that mock away the thing being tested, or have assertions that always pass
  • Hallucinated assertions — Agents may assert behavior that doesn’t match reality
  • Copy-paste tests — Similar tests that don’t add meaningful coverage

Always verify tests can fail when they should.

Test-first workflow

Section titled “Test-first workflow”
  1. Write or generate tests first: “Given this requirement [describe], write tests that would verify correct implementation.”
  2. Review and refine: Ensure tests capture what you actually want.
  3. Generate implementation: “Here are the tests. Write code that makes them pass.”
  4. Verify everything: Run tests, review implementation, check for gaps.

This produces better results than implementation-first because tests define the contract.

Prompt patterns

Section titled “Prompt patterns”

Unit tests:

Write unit tests for this function:
[paste function]


Cover:
- Normal operation
- Edge cases (empty input, null, boundaries)
- Error conditions


Use [test framework]. Follow conventions in [example file].

Regression test:

Bug fixed: [description]
Root cause: [explanation]
Fix: [summary]


Write a test that would catch this bug if it returns.

Documentation

Section titled “Documentation”

Types and approaches

Section titled “Types and approaches”

Code documentation: Inline comments (explain the why), function/method docs, class/module docs. Agents excel here because they read code and infer what needs documenting.

API documentation: Endpoints, SDKs, integration guides. Generate from code, OpenAPI specs, or examples.

Architecture documentation: System overviews, decision records, diagrams. More human guidance needed, but agents help with generation.

What to watch for

Section titled “What to watch for”
  • Hallucinated features — APIs that don’t exist, parameters that don’t work. Verify all claims against actual code.
  • Missing context — Why decisions were made, gotchas, performance considerations. Add these manually—they’re often most valuable.
  • Staleness risk — Easy to generate ≠ easy to maintain. Build update processes, not just generation.

Prompt patterns

Section titled “Prompt patterns”

README bootstrap:

Create a README for this project.


Project: [describe project]
Tech stack: [list technologies]
Target audience: [who will use this]


Include: installation, quick start, basic usage, contributing.

API documentation:

Generate API documentation for this endpoint:


[paste endpoint code or OpenAPI spec]


Include: description, parameters, request/response examples, error codes.
Format as Markdown.

ADR:

Help me write an ADR for choosing [option].


Context: [describe situation]
Decision: [what we decided]
Consequences: [what this means]


Include alternatives considered.

Resources

Section titled “Resources”

Testing

Section titled “Testing”

Documentation

Section titled “Documentation”