A testing guide for Java applications using JUnit 5 and Mockito. It covers unit tests, test doubles that imitate dependencies, and TDD, a method of writing tests before the code they check.

Use it to choose test types, write JUnit tests, configure Mockito mocks and verifications, and review edge cases and test quality.

It helps produce tests that are independent, repeatable, and useful rather than tests that depend on fragile setup or excessive mocks.

How antoniovazquezaraujo/LeTrain configures OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to antoniovazquezaraujo/LeTrain. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/antoniovazquezaraujo/LeTrain/develop/.opencode/skills/test-master/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/antoniovazquezaraujo/LeTrain

Made for: OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/antoniovazquezaraujo/letrain/test-master/github.svg)](https://agentmods.dev/skills/antoniovazquezaraujo/letrain/test-master)

Your own site

<a href="https://agentmods.dev/skills/antoniovazquezaraujo/letrain/test-master"><img src="https://agentmods.dev/badge/skills/antoniovazquezaraujo/letrain/test-master/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/antoniovazquezaraujo/letrain/test-master"><img src="https://agentmods.dev/badge/skills/antoniovazquezaraujo/letrain/test-master.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 333 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00333
Opus 5.5	$0.00000	$0.00133
Sonnet 5.5	$0.00000	$0.00067
Haiku 4.5	$0.00000	$0.00033

Measured 1mo ago against content hash 0929feeff678, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

test-master 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 1mo 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.

.opencode/skills/test-master/SKILL.md · 25 lines

What it actually says

name: test-master description: Skill de maestría en testing (JUnit 5, Mockito). Úsala para asegurar pruebas unitarias robustas, mocks precisos y alta cobertura de código con un enfoque en BDD/TDD.

Test Master

Esta skill proporciona conocimiento experto sobre:

JUnit 5: Uso avanzado de anotaciones, ciclos de vida de tests (@BeforeEach, @AfterEach, @Nested) y pruebas parametrizadas.
Mockito: Dominio de mock(), spy(), verify(), ArgumentCaptor y when().thenReturn().
Estrategia de Testing: TDD (Test Driven Development) y BDD (Behavior Driven Development).

Cómo utilizar esta Skill

1. Definición de Tests

Usa STRATEGY.md para determinar si una clase necesita tests unitarios, de integración o tests de estado (muy comunes en LeTrain para el mapa y las rutas).

2. Implementación con Mockito

Consulta MOCKITO_PATTERNS.md para evitar problemas comunes como stubbing excesivo o brittle tests.

3. Checklist de Calidad de Testing

Antes de validar un cambio, Bicho debe responder:

¿Es el test independiente y determinista?
¿Cubre casos borde (ej. rutas nulas, desconexión de vías, economía cero)?
¿Se están usando los verify adecuados en lugar de solo probar el estado final?

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

references/mockito-patterns.md 1.1 KB

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.

1mo ago First seen · 25 lines · 0 tokens per session scan A 0929feeff678

Subscribe to this mod's changes

test-master is a skill published in the GitHub repository antoniovazquezaraujo/LeTrain (49 stars, last pushed today), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 333 tokens. 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 2026-09-04.

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LeTrain: Skill for OpenCode