HSEmulate Morgan Z West

Use this command to install HSEmulate:

winget install --id=MorganZWest.HSEmulate -e

Local emulator for HubSpot custom-coded workflow actions

HubSpot Emulator (hsemulator)

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 real workflow event payloads, 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.

Why hsemulator exists

Developing HubSpot custom code today typically means:

Writing code in an editor
Copying it into the HubSpot UI
Triggering a workflow
Reading logs in a browser
Repeating

hsemulator replaces that loop with a local, deterministic workflow:

Code stays in your editor
Events are fixtures
Failures are explicit
Regressions are caught automatically

No UI-driven iteration required.

When to use it

Use hsemulator when you want to:

Develop and debug HubSpot custom code locally
Validate logic using real workflow event payloads
Catch regressions with assertions and snapshots
Enforce execution limits during development or CI
Reduce copy–paste cycles into the HubSpot UI

Do not use it to:

Fully emulate HubSpot’s runtime or infrastructure
Mock HubSpot APIs or rate limits
Replace integration or end-to-end tests

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
CI-friendly, machine-readable output

Documentation

📖 Full documentation is available on Read the Docs:

👉 Read our Documentation

Start here if you want:

Installation instructions
Project structure
Configuration reference
Assertions, snapshots, budgets, and CI usage

Developer notes (Rust / Cargo)

hsemulator is written in Rust and distributed as a standalone binary.

Building locally

cargo build

Running from source

cargo run -- run

Release builds

cargo build --release

The release binary is what gets packaged into the installer. End users do not need Rust or Cargo installed.

High-level architecture

At a high level, hsemulator works like this:

fixture.json
     │
     ▼
runtime shim (Node / Python)
     │
     ▼
your HubSpot custom code
     │
     ▼
structured JSON output
     │
     ├─ assertions
     ├─ budgets
     └─ snapshots

Each run is isolated, deterministic, and fully observable.

Contributing / feedback

Issues, bug reports, and feature requests are welcome:

👉 https://github.com/morganzwest/hsemulator/issues

License

MIT