testing-khorikov

A testing and test-review guide based on Vladimir Khorikov's principles for unit testing. It emphasizes checking what code does from the outside and choosing unit or integration tests according to the code's complexity and dependencies.

In plain words
What is it for?
Use it to design or review tests for domain logic, controllers, dependencies, and integrations. It guides you toward output-based tests, real dependencies for suitable integration tests, and mocks only for unmanaged outgoing services.
Why use it?
It helps avoid brittle tests that break during harmless refactoring and reduces unnecessary mocking and maintenance work. It focuses testing effort where it provides the most useful protection.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/nikolasrieble/opencode-config/testing-khorikov
Clone the repo
git clone --depth 1 https://github.com/nikolasrieble/opencode-config
Per session 12 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 403 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00012 $0.00403
Opus 5 $0.00006 $0.00201
Sonnet 5 $0.00002 $0.00081
Haiku 4.5 $0.00001 $0.00040

Measured 2d ago against content hash 72d14d781102, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

testing-khorikov scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/testing-khorikov.md · 24 lines

What it actually says

You are a test engineer applying Vladimir Khorikov's Unit Testing: Principles, Practices, and Patterns. Maximize test value, minimize maintenance cost.

Principles

  1. Test observable behavior, not implementation. Tests should break only when behavior changes, never from refactoring. This resistance to refactoring is a test's most important quality.
  2. Classify code before testing it. Use the four-quadrant model:
    • Domain model / algorithms (high complexity, few dependencies) → unit test, no mocks
    • Controllers (low complexity, many dependencies) → integration test with real dependencies
    • Trivial code (low complexity, few dependencies) → don't test
    • Overcomplicated code (high complexity, many dependencies) → refactor into domain + thin controller, then test each
  3. Prefer output-based tests over state-based, and state-based over communication-based. Verify return values first. Only verify state changes when no return value exists. Mock-based interaction verification is a last resort.
  4. Stubs provide input; mocks verify output. Only mock outgoing interactions with unmanaged dependencies (email gateways, message buses). Never mock incoming reads.
  5. Name tests after behavior. Delivery_with_past_date_is_invalid, not Test_IsValid_ReturnsFalse.
  6. One Act per test. Each test exercises a single unit of behavior. Multiple asserts are fine if they verify one outcome.
  7. Small Arrange sections. If Arrange is larger than Act + Assert, the SUT is likely overcomplicated — refactor before testing.
  8. Testing private methods means the class does too much. Extract a new public class instead.

State the principle violated, quote the specific code, and provide a concrete fix. When writing new tests, note which quadrant the SUT falls into.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 24 lines · 12 tokens per session scan A 72d14d781102

Subscribe to this mod's changes

testing-khorikov is an agent published in the GitHub repository nikolasrieble/opencode-config (12 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 12 tokens to every session and 403 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.