Welcome to TestFlows Machine

[naulius]

TestFlows Machine is a deterministic hypervisor and execution environment. Record a run of your software, replay it exactly, and branch it from any point to explore what else could have happened.

Steer threads into the order a race needs, and inject faults into system calls, memory, disks, containers, clocks and networks. Debug with time travel: go back to the point of failure and run debugging commands right there, step backwards as well as forwards, add logging after the fact, or use GDB inside the machine. Time compression skips idle waits, so sleeps and timeouts take almost no time. Your programs, Docker images and Docker Compose projects run in it unchanged.

Machine is in public beta. We're improving it quickly, and what you tell us here decides what we work on next.

Getting started

• Sign up: every account starts on the free plan
• Install the client: one command, and it signs you in
• Your first run: five commands from a Python script to its output
• Examples: data races, starvation and missed wakeups to explore with branches and replay
• Python SDK: drive runs, branches, replays and faults from your tests

Where to post

• Q&A for questions about using Machine. Mark the answer that solved it, so the next person finds it.
• Ideas for features and changes you'd like to see.
• Show and tell for what you found or built with Machine: a bug it caught, a test it made reliable, a script others can use.
• General for everything else.

Found a bug? Open an issue with the commands you ran and the output of machine --version.

Before you post

• Discussions are public. Never include an API key, a token, a password or other secrets, and remove them from any output you paste.
• Account and billing questions go to support@testflows.com, never here.
• Report a security vulnerability privately. See SECURITY.md.
• Everyone here follows our Code of Conduct.

Tell us what you're testing, what worked and what got in your way.