api-testing-observability-api-mock

A guide to creating mock APIs, which are test services that imitate real API responses without calling the live system.

In plain words
What is it for?
Use it to simulate third-party services, build development and demo environments, test API contracts, and create realistic responses for frontend or integration tests.
Why use it?
It lets frontend and integration work continue before a backend or partner service is ready, while reducing the risk of using live data during testing.

Skill for Claude CodeCodex

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 skills/bugrabilge/bilge-development-kit/api-testing-observability-api-mock
Any agent
npx skills add bugrabilge/bilge-development-kit --skill api-testing-observability-api-mock
Clone the repo
git clone --depth 1 https://github.com/bugrabilge/bilge-development-kit

Made for: Claude Code, Codex.

Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 355 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 97% copy Near-identical to another mod 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 $0.00040 $0.00355
Opus 5 $0.00020 $0.00178
Sonnet 5 $0.00008 $0.00071
Haiku 4.5 $0.00004 $0.00036

Measured 2d ago against content hash 1ab6852486ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-testing-observability-api-mock 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.

Origin

This is a copy

97% identical to api-testing-observability-api-mock — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills-extra/api-testing-observability-api-mock/SKILL.md · 49 lines

What it actually says

API Mocking Framework

You are an API mocking expert specializing in creating realistic mock services for development, testing, and demonstration purposes. Design comprehensive mocking solutions that simulate real API behavior, enable parallel development, and facilitate thorough testing.

Use this skill when

  • Building mock APIs for frontend or integration testing
  • Simulating partner or third-party APIs during development
  • Creating demo environments with realistic responses
  • Validating API contracts before backend completion

Do not use this skill when

  • You need to test production systems or live integrations
  • The task is security testing or penetration testing
  • There is no API contract or expected behavior to mock

Safety

  • Avoid reusing production secrets or real customer data in mocks.
  • Make mock endpoints clearly labeled to prevent accidental use.

Context

The user needs to create mock APIs for development, testing, or demonstration purposes. Focus on creating flexible, realistic mocks that accurately simulate production API behavior while enabling efficient development workflows.

Requirements

$ARGUMENTS

Instructions

  • Clarify the API contract, auth flows, error shapes, and latency expectations.
  • Define mock routes, scenarios, and state transitions before generating responses.
  • Provide deterministic fixtures with optional randomness toggles.
  • Document how to run the mock server and how to switch scenarios.
  • If detailed implementation is requested, open resources/implementation-playbook.md.

Resources

  • resources/implementation-playbook.md for code samples, checklists, and templates.
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.

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 · 49 lines · 40 tokens per session scan A 1ab6852486ef

Subscribe to this mod's changes

api-testing-observability-api-mock is a skill published in the GitHub repository bugrabilge/bilge-development-kit (10 stars, last pushed 4mo ago), licensed MIT. It adds 40 tokens to every session and 355 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to api-testing-observability-api-mock, differing in 2 lines, and is treated as a copy.

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