Skill: Testing Nx

Goal

Configure and run tests across multiple projects using Nx affected detection for efficient workspace-wide testing with proper caching.

Use This Skill When

•Running tests for multiple projects in workspace
•Using Nx project graph for affected project detection
•Setting up CI/CD test pipelines
•The user asks to "run affected tests" or "set up Nx testing"

Do Not Use This Skill When

•Single project without Nx (use direct test framework skill)
•Need to test all projects regardless of changes
•Project doesn't use Nx

Nx Test Configuration

nx.json Configuration

json

{
  "$schema": "./node_modules/nx/schemas/nx-schema.json",
  "namedInputs": {
    "default": ["{projectRoot}/**/*", "sharedGlobals"],
    "production": ["default"],
    "sharedGlobals": []
  },
  "targetDefaults": {
    "test": {
      "inputs": ["production", "^production"],
      "cache": true
    },
    "lint": {
      "inputs": ["default"]
    }
  }
}

project.json Configuration

json

{
  "name": "my-package",
  "$schema": "../../node_modules/nx/schemas/project-schema.json",
  "targets": {
    "test": {
      "command": "vitest run",
      "inputs": ["default", "^production"],
      "outputs": ["coverage"]
    },
    "test:watch": {
      "command": "vitest watch"
    }
  }
}

Running Tests

Affected Tests

bash

# Run tests for affected projects only
nx affected --target=test

# Run tests and build
nx affected --target=test --target=build

# With specific base branch
nx affected --target=test --base=main

# With files that changed
nx affected --target=test --files src/utils.ts

# Parallel execution
nx affected --target=test --parallel=4

# Max parallelization
nx affected --target=test --parallel=max

All Project Tests

bash

# Run all project tests
nx run-many --target=test --all

# Run specific projects
nx run-many --target=test --projects=project-a,project-b

# With parallelization
nx run-many --target=test --all --parallel=4

Individual Project Tests

bash

# Run test for specific project
nx run my-project:test

# With configuration
nx run my-project:test --configuration=ci

# Watch mode
nx run my-project:test --watch

Test Caching

Enable Caching

json

// project.json
{
  "targets": {
    "test": {
      "command": "vitest run",
      "cache": true,
      "inputs": ["default", "^production"]
    }
  }
}

Cache Configuration

bash

# Set cache location
NX_CACHE_LOCATION=/tmp/nx-cache

# Disable cache
NX_DONT_USE_CACHE=1

# Custom cache duration
NX_CACHE_PROJECT_AGE=7d

CI/CD Pipeline Integration

GitHub Actions

yaml

name: Tests

on:
  push:
    branches: [main]
  pull_request:

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      
      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: 'pnpm'
      
      - name: Install dependencies
        run: pnpm install
      
      - name: Install Nx
        run: pnpm add -D nx
      
      - name: Cache Nx
        uses: actions/cache@v3
        with:
          path: .nx/cache
          key: ${{ runner.os }}-nx-${{ hashFiles('**/pnpm-lock.yaml') }}
      
      - name: Run Affected Tests
        run: nx affected --target=test --base=origin/main

GitLab CI

yaml

test:
  image: node:20
  script:
    - npm ci
    - npx nx affected --target=test --base=main
  rules:
    - if: $CI_COMMIT_BRANCH == "main"

Parallelization Strategy

With Parallel Count

bash

# Use 4 parallel workers
nx affected --target=test --parallel=4

# Use all available cores
nx affected --target=test --parallel=max

Resource Management

bash

# Run on specific machine type (with labels)
nx run my-project:test --target-machine-type=large

# With memory limits
NX_MAX_MEMORY=4GB nx affected --target=test

Test Reporting

JUnit Output

typescript

// vitest.config.ts
export default defineConfig({
  test: {
    reporters: ['default', 'junit'],
    junitReporter: {
      outputFile: 'test-results.xml'
    }
  }
});

Nx Reports

bash

# Generate HTML report
nx report

# Test results in CI
nx affected --target=test --output-style=stream

Output Formats

Format	Flag	Use Case
Stream	`--output-style=stream`	Local development
Static	`--output-style=static`	CI/CD logs
JSON	`--output-style=json`	Programmatic parsing
Nx Cloud	`nx cloud`	Distributed caching

Workspace Structure

code

nx.json
project.json (project A)
project.json (project B)
packages/
├── pkg-a/
│   ├── project.json
│   └── src/
│       └── module.test.ts
└── pkg-b/
    ├── project.json
    └── src/
        └── module.test.ts

Best Practices

1. Configure Targets Properly

json

{
  "targets": {
    "test": {
      "command": "vitest run",
      "inputs": ["default", "^production"],
      "outputs": ["coverage"]
    }
  }
}

2. Use Named Inputs

json

{
  "namedInputs": {
    "production": [
      "default",
      "!{projectRoot}/**/*.test.ts",
      "!{projectRoot}/**/*.spec.ts"
    ]
  }
}

3. Cache Test Results

bash

# Verify caching works
nx test my-project --skip-nx-cache

# First run (cache miss)
time nx test my-project

# Second run (cache hit)
time nx test my-project

4. CI Optimization

bash

# Install Nx globally for faster execution
npm i -g nx

# Use CI mode for better performance
nx connect
nx cloud

Troubleshooting

Tests Not Running

bash

# Check project graph
nx graph

# List affected projects
nx show projects --affected --base=main

# Verify target exists
nx show project my-project --target=test

Cache Issues

bash

# Clear cache
nx reset

# Check cache location
echo $NX_CACHE_LOCATION

Performance Issues

bash

# Analyze performance
nx report

# With profiling
NX_PROFILE=profile.json nx affected --target=test

Output

•nx.json configuration for testing
•project.json target configurations
•CI/CD pipeline examples (GitHub Actions, GitLab)
•Test reporting setup
•Cache configuration

References

•Nx testing: https://nx.dev/recipes/testing
•Affected: https://nx.dev/concepts/affected
•Nx caching: https://nx.dev/concepts/caching