Overview

Workers IO docs use four core ideas: workloads, mocks, faults, and simulations. These are the pieces you define to turn one important product behavior into many realistic runs.

Workloads

A workload is the command that drives behavior your users depend on. It sets up state, performs operations, and checks invariants.

Read Test Workloads to design one.

Mocks

Mocks describe external service behavior. Use them for APIs, webhooks, providers, and services you do not want the run to call directly.

The project-level mock file is:

.workers/external-mocks.json

Read Mocks to model external services.

Faults

Faults describe operating conditions the workflow should survive. Network faults are available today; storage, service shutdown, resource pressure, and scheduler pressure faults are coming soon.

Named CLI network faults live under:

.workers/fault/net/

Read Faults to model operating conditions.

Simulations

A simulation runs one workload across seeds and fault models. Each seed explores a different scenario. Each failure gives you logs, captured inputs, artifacts, and the exact workload and fault context used for the run.

Read Simulations to run workloads, inspect failures, rerun cases, and verify fixes.