Homebrew Testing

This example demonstrates testing Homebrew packages in a clean, isolated macOS environment. Unlike your host machine cluttered with dependencies, a fresh VM sandbox ensures reproducible testing conditions.

Why use a sandbox?

Testing Homebrew formulas on your host has problems:

Dependency pollution — Existing packages may mask missing dependencies
State accumulation — Previous installs leave behind configs and files
Risk of breakage — Testing can corrupt your development environment

A macOS VM sandbox solves these:

Clean slate — Every test starts from a known state
Isolation — Bad installs don't affect your host
Reproducibility — Others can replicate your exact environment

Prerequisites

Sandbox VM set up
A "golden image" VM for quick resets

Create a golden image

Before testing, create a clean snapshot you can restore:

# Stop the sandbox if running
lume stop sandbox

# Create a golden image
lume clone sandbox sandbox-golden

# Now you can always reset to this clean state

Example prompt

Ask Claude Code:

"SSH into the sandbox. Install the 'jq' Homebrew formula, verify it works by parsing some JSON, then tell me if it installed correctly."

What Claude does

Connects to the sandbox via SSH
Installs the formula with brew install
Tests the installation with sample data
Reports results including version and functionality

Example session

You: SSH into lume@192.168.64.5. Test the 'jq' Homebrew formula -
     install it, verify it parses JSON correctly, and report the results.

Claude: I'll connect to the sandbox and test the jq formula.

[Runs: ssh lume@192.168.64.5]

First, let me check if Homebrew is installed:

[Runs: brew --version]
Homebrew 4.2.0

Now installing jq:

[Runs: brew install jq]
==> Downloading https://ghcr.io/v2/homebrew/core/jq/manifests/1.7.1
==> Fetching jq
==> Installing jq
==> Pouring jq--1.7.1.arm64_sonoma.bottle.tar.gz
/opt/homebrew/Cellar/jq/1.7.1: 19 files, 1.4MB

Verifying the installation:

[Runs: jq --version]
jq-1.7.1

Testing JSON parsing:

[Runs: echo '{"name": "test", "values": [1, 2, 3]}' | jq '.name']
"test"

[Runs: echo '{"name": "test", "values": [1, 2, 3]}' | jq '.values | add']
6

Testing with a more complex query:

[Runs: curl -s https://api.github.com/repos/jqlang/jq | jq '{name, stars: .stargazers_count, language}']
{
  "name": "jq",
  "stars": 28534,
  "language": "C"
}

Test Results:
- Installation: Success
- Version: jq-1.7.1
- Basic parsing: Working
- Array operations: Working
- API response parsing: Working

The jq formula installed correctly and all functionality tests passed.

Resetting for the next test

After testing, reset the sandbox to the clean state:

# Stop and delete the modified sandbox
lume stop sandbox
lume delete sandbox

# Restore from golden image
lume clone sandbox-golden sandbox

# Start fresh for the next test
lume run sandbox --no-display --shared-dir ~/my-project

Or automate it in a script:

#!/bin/bash
# reset-sandbox.sh

VM_NAME="sandbox"
GOLDEN_IMAGE="sandbox-golden"

lume stop $VM_NAME 2>/dev/null
lume delete $VM_NAME 2>/dev/null
lume clone $GOLDEN_IMAGE $VM_NAME
lume run $VM_NAME --no-display

echo "Sandbox reset complete"

Testing your own formula

If you're developing a Homebrew formula:

You: SSH into the sandbox. Install my formula from ./my-formula.rb in the shared folder
     and verify it works.

Claude: I'll test your local formula.

[Runs: ssh lume@192.168.64.5]
[Runs: cd /Volumes/My\ Shared\ Files]
[Runs: brew install --formula ./my-formula.rb]

# Claude tests the installed tool and reports any issues

Common testing scenarios

Test a formula with dependencies

You: Install 'ffmpeg' and verify video conversion works.

Claude will install ffmpeg with all its dependencies and test encoding.

Test formula upgrades

You: The sandbox has jq 1.6. Upgrade to 1.7 and verify nothing breaks.

Test conflicting packages

You: Try installing both 'python@3.11' and 'python@3.12', then test importing
     packages in each version.

Verify formula uninstallation

You: Install jq, uninstall it, and verify it's completely removed with no leftover files.

Why this matters

Testing Approach	Clean Environment	Isolated	Resettable
Host machine	No	No	No
Docker	Yes	Yes	Yes (but no macOS)
macOS VM	Yes	Yes	Yes

Homebrew is macOS-specific. Testing Homebrew formulas requires macOS, and testing them properly requires isolation.

Next steps

Sandbox Setup — Initial VM configuration
Claude Cowork with MCP — Use MCP for native VM integration
Unattended Setup — Pre-configure VMs with Homebrew

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