HubSpot Emulator

hsemulator is a local test runner for HubSpot Workflow Custom Code Actions.

It allows you to run the exact JavaScript or Python code you paste into HubSpot locally, using fixture events, with support for assertions, snapshots, execution budgets, and flaky-run detection.

The goal is to make developing HubSpot custom code feel closer to Lambda-style local development—without relying on the HubSpot UI for iteration.

When to Use It

Use hsemulator when you want to:

  • Develop and debug HubSpot custom code locally

  • Validate logic using real workflow event payloads

  • Detect regressions with assertions and snapshots

  • Enforce performance limits (time / memory)

  • Reduce copy–paste cycles into the HubSpot UI

Do not use it to:

  • Fully emulate HubSpot’s infrastructure

  • Mock HubSpot APIs or rate limits

  • Replace integration or end-to-end tests (in development)

Core Capabilities

  • Local execution of JS and Python custom code actions

  • Fixture-based event input

  • Assertions against output and metadata

  • Snapshot testing for regression detection

  • Execution budgets (time and memory)

  • Flaky-run detection via repeat execution

  • Machine-readable summary output (CI-friendly)

Documentation

Scope and Non-Goals

hsemulator is intentionally focused.

It does not attempt to:

  • Fully reproduce HubSpot’s runtime environment

  • Provide API mocks or request replay

  • Replace production monitoring or E2E tests

Its purpose is fast, deterministic local iteration.