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Simulacat

pytest fixtures that run tests against a local, stateful GitHub API simulator. Scenario configuration, seeded repository state, and no rate limits.

Introduction

Prerequisites

Installation

Bundled simulator assets

Installing Simulacrum dependencies

Compatibility matrix

Known incompatibilities and workarounds

pytest Fixtures

github_sim_config (advanced)
Helper Functions

Simulator Orchestration

Starting the Simulator
Stopping the Simulator
Empty Configuration
Error Handling
Custom Bun Executable

Scenario configuration helpers

Example: single repo, single user
Example: multiple repositories with public and private visibility
Optional issues and pull requests
Named scenario factories
Authentication tokens
GitHub App installation metadata
Authentication mode limitations

Configuration Schema

User Schema
Repository Schema
Branch Schema

Pytest fixtures

Scenario fixtures
github_sim_config
github_simulator

Environment Variables

Running tests

Continuous integration (CI) reference projects

Troubleshooting

Simulator startup failures
Configuration serialization errors
`github3.py` and simulator coverage mismatches

API stability

Deprecation policy

Changelog

Source

Source material

Contents

Introduction
- Introduction
Prerequisites
- Prerequisites
Installation
- Installation
Bundled simulator assets
- Bundled simulator assets
Installing Simulacrum dependencies
- Installing Simulacrum dependencies
Compatibility matrix
- Compatibility matrix
- Known incompatibilities and workarounds
pytest Fixtures
Simulator Orchestration
Scenario configuration helpers
Configuration Schema
Pytest fixtures
Environment Variables
- Environment Variables
Running tests
- Running tests
Continuous integration (CI) reference projects
- Continuous integration (CI) reference projects
Troubleshooting
API stability
- API stability
Deprecation policy
- Deprecation policy
Changelog
- Changelog

Introduction

Updated Jul 14, 2026

simulacat provides a pytest integration for running tests against a local GitHub API simulator powered by @simulacrum/github-api-simulator.

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