Testing

What it does

When your agent uses it

• Failing/flaky tests
• Tasks that involve Test generation
• Tasks that involve Failing and flaky tests

Example prompts

• “/testing”

Workflow steps

8 steps, taken from the first numbered list in SKILL.md.

1. 1ASYNC BY DEFAULT — Use async: true unless tests modify global state
2. 2SANDBOX ISOLATION — All database tests use Ecto.Adapters.SQL.Sandbox
3. 3MOCK ONLY AT BOUNDARIES — Never mock database, internal modules, or stdlib
4. 4BEHAVIOURS AS CONTRACTS — All mocks must implement a defined @callback behaviour
5. 5BUILD BY DEFAULT — Use build/2 in factories; insert/2 only when DB needed
6. 6NO PROCESS.SLEEP — Use assert_receive with timeout for async operations
7. 7VERIFY_ON_EXIT! — Always call in Mox tests setup
8. 8FACTORIES MATCH SCHEMA REQUIRED FIELDS — Factory definitions must include all fields that have validate_required in the schema changeset…

What it can do on your machine

Read from SKILL.md and the folder at commit 9767a82. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are elixir).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Testing loads about 750 tokens when it runs, and up to ~3.8k if it reads all its reference files. Until then it costs about 61 tokens; SKILL.md has 268 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~61

When it runs · the whole SKILL.md, loaded when a task matches

~750

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from oliver-kriska/claude-elixir-phoenix at commit 9767a82, republished under its MIT licence (© oliver-kriska). 268 words, ~750 tokens.

name

testing

description

Write or repair Elixir tests with ExUnit, sandbox isolation, async reliability, Mox, ExMachina, and LiveViewTest. Use for test files, test setup, or failing/flaky tests. NOT for investigating an application bug outside the test suite.

# Setup chain
setup [:create_user, :authenticate]

# Pattern matching assertion
assert {:ok, %User{name: name}} = create_user(attrs)

# Async message assertion
assert_receive {:user_created, _}, 5000

# Mox setup
setup :verify_on_exit!
expect(MockAPI, :call, fn _ -> {:ok, "data"} end)

# LiveView async
html = render_async(view)  # MUST call for assign_async

© oliver-kriska, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 4 other files (references) in targets/pi/skills/testing of oliver-kriska/claude-elixir-phoenix.

• SKILL.md
• references/exunit-patterns.md
• references/factory-patterns.md
• references/liveview-testing.md
• references/mox-patterns.md

Open the folder on GitHubat commit 9767a82