test-double

Suite of C/C++ tooling built on LLVM/Clang

Lowkey Vault is a small test double for Azure Key Vault. Developer feedback needed, please vote here: https://github.com/nagyesta/lowkey-vault/discussions/272

A simple in-memory data storage for PHP

A strict mocking solution. It works with any testing framework; the examples below use PHPUnit.

This guide clarifies the differences between dummies, stubs, fakes, spies, and mocks. It includes practical examples and attempts to clarify the optimal use cases for each type.

A recording stand-in for the supabase-js query builder: records the calls a test can assert on, never simulates a database.

Emulate ESC/POS thermal printers on real IP addresses. Live paper feed, searchable job history, duplicate detection and failure injection — test receipt printing without hardware.

Rehearse strict behavior with testdouble.js

A black-box mock SAP endpoint: OData V2, BAPI/RFC and IDoc shapes over SQLite, with zero dependencies.

A fake x402 endpoint for testing payment clients — spec-faithful 402 challenges, no crypto/wallet/funds. pytest fixture + context manager + standalone CLI, with failure injection.

SCEP testing suite — a SCEP client, a test CA, and an Intune/MS Graph endpoint simulator for exercising third-party SCEP enrollment.

To explain test doubles in PHPUnit by using various examples.

Fake AG-UI agent backend for testing. Deterministic scripted event streams, session record & replay, failure injection. No LLM needed. Mounts into FastAPI/Starlette or runs standalone.

A demonstration of isolating unit tests

Deterministic, offline test double for the Anthropic Messages API — unit-test agent loops with no API key and no network

spring-gradle

Examples of TDD use cases using Go

Test mocks for Zig. Call trackers, string spies, return mocks, error mocks — zero dependencies.

Testo adapter for the understudy test double library: automatic verification and cleanup after every test

Test double library for PHP with a call-closure API (work in progress)