nx-monorepo-generator

name

nx-monorepo-generator

description

Use when adding Jest testing configuration to Nx projects, running `nx g @nx/jest:configuration`, setting up testing infrastructure, or troubleshooting tests that fail after running the Jest generator. Ensures proper TypeScript moduleResolution (nodenext), testing enhancement libraries (jest-dom, user-event, MSW), and monorepo pattern adherence. Triggers: "add tests", "setup Jest", "configure testing", "Jest not working", "moduleResolution error", "tests failing after generator

Nx Monorepo Generator - Jest Configuration Workflow

The Nx Jest generator produces defaults that conflict with this workspace's standards. This skill ensures all mandatory post-generation fixes are applied.

Phase 1: Determine Project Type

Identify the project type before generating:

Type	Examples	Testing Needs
UI	web apps, mobile	Full stack: jest-dom, user-event, MSW
Node	server, APIs	jest-dom + conditional MSW
Logic	schemas, utils	Basic Jest only

How to identify:

• Check project.json executors (React/Next.js = UI, Node = server)
• Schema/utility libraries = Logic
• When uncertain, ask the user

Phase 2: Generate Configuration

pnpm exec nx g @nx/jest:configuration <project-name>

Creates: jest.config.ts, tsconfig.spec.json, updates project.json

Warning: Generated config has incorrect defaults - proceed to Phase 3.

Phase 3: Post-Generation Fixes

Execute ALL applicable steps. See references/post-gen-checklist.md for full details.

Step	UI	Node	Logic	Script
Install testing libs	✅	✅	❌	scripts/install-testing-libs.sh
Create jest.setup.ts	✅	❌	❌	Manual
Update jest.config.ts	✅	❌	❌	Manual
Fix moduleResolution	✅	✅	✅	scripts/fix-tsconfig-spec.sh
Verify Jest types	✅	✅	✅	scripts/validate-jest-config.sh
Clean production config	✅	✅	✅	scripts/validate-jest-config.sh

Critical Fix: TypeScript moduleResolution

In tsconfig.spec.json, change:

• "module": "commonjs" → "module": "nodenext"
• "moduleResolution": "node10" → "moduleResolution": "nodenext"

Why: Workspace uses customConditions requiring modern module resolution.

Phase 4: Validation

# Automated validation
scripts/validate-jest-config.sh <project-path>

# Run tests
pnpm exec nx run <project-name>:test

Success indicators:

• ✅ Tests run without TypeScript errors
• ✅ No module resolution warnings
• ✅ Coverage reports generate correctly

References

• references/post-gen-checklist.md - Step-by-step checklist with code examples
• references/jest-config-patterns.md - Configuration structure and rationale
• references/testing-standards.md - user-event, MSW, jest-dom patterns

Scripts

• scripts/validate-jest-config.sh <path> - Validate configuration against standards
• scripts/install-testing-libs.sh <type> <path> - Install testing packages by project type
• scripts/fix-tsconfig-spec.sh <path> - Auto-fix moduleResolution settings

Key Principle

Generated code rarely matches monorepo patterns. Post-generation fixes are MANDATORY. This skill ensures consistency and prevents pattern drift that causes mysterious failures.

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Source: ForceInjection/domain-driven-design-skills — distributed by TomeVault.