Jest Cheat Sheet

Jest cheat sheet with real commands and snippets for setup, core workflows, debugging, and production-safe automation patterns. If you are working across tools, pair this with the Cypress Cheat Sheet and CircleCI Cheat Sheet.

Setup and Installation

Goal: Verify installation and CLI metadata

# Resolve command path from current shell
command -v jest

# Print installed version to confirm runtime
jest --version

# Read top-level help before using subcommands
jest --help

Goal: Install or upgrade the tool on a workstation

# Install Jest as a dev dependency
npm install -D jest @types/jest

# Confirm Jest is available via npx
npx jest --version

Goal: Run day-to-day commands

# Run Jest test suite
npx jest

# Run tests in watch mode
npx jest --watch

# Generate coverage report
npx jest --coverage

# Run only changed files
npx jest -o

Core Workflows

Goal: Capture command help for quick offline lookup

# Create docs folder for generated command references
mkdir -p docs/cli

# Write help output to a timestamped file
jest --help > docs/cli/jest-help.txt

# Search help output for a keyword
rg "config|auth|deploy" docs/cli/jest-help.txt

Goal: Wrap repetitive commands in a script

# Create scripts directory for local automation
mkdir -p scripts

# Write repeatable health-check script
cat > scripts/check-jest.sh <<'SH'
#!/usr/bin/env bash
set -euo pipefail
jest --version
jest --help >/dev/null
SH

# Make script executable and run it
chmod +x scripts/check-jest.sh && ./scripts/check-jest.sh

Configuration and Environment

Goal: Pin environment variables for predictable runs

# Define environment profile for local commands
export JEST_PROFILE=dev

# Persist profile in local shell configuration
echo 'export JEST_PROFILE=dev' >> ~/.zshrc

# Reload shell profile changes
source ~/.zshrc

Automation and CI

Goal: Add tool checks to CI pipeline

# Run lint/test/build in strict mode
set -euo pipefail

# Verify CLI exists before invoking workflow
command -v jest

# Exit quickly if command is unavailable
jest --version

Debugging and Troubleshooting

Goal: Collect diagnostics when commands fail

# Capture command output and exit code
jest --help > /tmp/jest-debug.log 2>&1; echo $?

# Inspect captured diagnostics
tail -n 80 /tmp/jest-debug.log

# Check current shell PATH entries
echo $PATH | tr ':' '\n'

Common Gotchas

• Pin Jest versions in CI so local and pipeline behavior match.
• Check tool authentication context before running write or deploy commands.
• Prefer non-interactive flags in scripts to avoid stalled jobs.
• Capture stderr logs in CI artifacts for faster incident triage.
• Keep secrets in environment variables, not committed scripts.

Related Sheets

• Cypress Cheat Sheet — daily Cypress commands and production-ready examples.
• CircleCI Cheat Sheet — daily CircleCI commands and production-ready examples.
• GitHub Actions Cheat Sheet — daily GitHub Actions commands and production-ready examples.