Frequently Asked Questions

Find answers to the most common questions about Karate testing framework.

Getting Started

What is Karate?

Karate is the only open-source tool to combine API test-automation, mocks, performance-testing and even UI automation into a single, unified framework. Tests are written in plain text using Gherkin syntax, making them readable by anyone.

Do I need to know programming to use Karate?

No! Karate tests are written in plain text using a simple, readable syntax. However, some programming knowledge helps with advanced features like custom JavaScript functions and Java interop.

Feature: Check if user exists

Scenario: Get user information
Given url 'https://api.example.com'
And path 'users', 123
When method GET
Then status 200
And match response.name == 'John Doe'

How does Karate compare to other testing tools?

Detailed Comparison Matrix:

Feature	Karate	Rest Assured	Postman	Cypress	Selenium
API Testing	✅	✅	✅	❌	❌
UI Testing	✅	❌	❌	✅	✅
Performance Testing	✅	❌	❌	❌	❌
Mock Services	✅	❌	✅	❌	❌
No Programming Required	✅	❌	✅	❌	❌
Parallel Execution	✅	✅	❌	✅	✅
Built-in Assertions	✅	✅	✅	✅	❌
Cross-platform	✅	✅	✅	❌	✅
CI/CD Integration	✅	✅	✅	✅	✅
Test Reports	✅	❌	✅	✅	❌
Data-Driven Testing	✅	✅	❌	❌	❌
JSON/XML Support	✅	✅	✅	❌	❌

Key Advantages of Karate:

• Unified Framework: One tool for API, UI, performance, and mocks
• No Glue Code: Unlike Cucumber, no step definitions needed
• Better Assertions: More powerful than JSON Schema validation
• Built-in Debugging: Step-through debugging with VS Code/IntelliJ
• Simpler Syntax: More readable than Rest Assured Java code

When to Choose Karate vs Others:

Use Karate When	Use Alternatives When
Testing APIs and UIs together	Pure frontend testing (→ Cypress)
Team has mixed technical skills	Team is all Java developers (→ Rest Assured)
Need built-in mocking	Just need request collection (→ Postman)
Want unified reporting	Using separate specialized tools
Performance testing APIs	High-volume load testing (→ JMeter)

Installation & Setup

Corporate Proxy Issues

Q: The Maven archetype command fails when I'm behind a corporate proxy. How do I fix this?

If you are behind a corporate proxy, or especially if your local Maven installation has been configured to point to a repository within your local network, the Maven archetype command may not work.

Solution: One workaround is to temporarily disable or rename your Maven settings.xml file, and try again.

Dependency Conflicts and "Fat JAR" Solution

Q: I'm getting "class not found" errors when mixing Karate with other dependencies. How do I fix this?

If you mix Karate into a Maven or Gradle project with many other dependencies, you may run into problems because of dependency conflicts. For example, many Java projects directly (or indirectly) depend on Netty, Thymeleaf, or ANTLR.

Solution: Use the karate-core dependency with the all classifier in your pom.xml (or build.gradle):

<dependency>
  <groupId>io.karatelabs</groupId>
  <artifactId>karate-core</artifactId>
  <version>${karate.version}</version>
  <classifier>all</classifier>
  <scope>test</scope>
</dependency>

Advanced Solution: For very complicated projects, consider using a Maven profile so that testing-related dependencies don't collide with your development-time dependencies. Alternatively, you can have Karate tests in a separate stand-alone maven project and folder, while still being in the same Git repository.

Steps:

1. Locate your Maven settings.xml file (usually in ~/.m2/settings.xml or %USERPROFILE%\.m2\settings.xml)
2. Rename it temporarily (e.g., settings.xml.backup)
3. Run the Maven archetype command
4. Restore the original settings.xml file after project creation

How do I customize project structure for existing Maven/Gradle projects?

Q: I have an existing project and want to keep .feature files with .java files instead of in src/test/resources. How do I configure this?

The Maven archetype already sets this up correctly, but for existing projects you can configure Maven or Gradle to recognize test resources in your Java source directory.

Maven Configuration:

Add this to your pom.xml <build> section:

<build>
    <testResources>
        <testResource>
            <directory>src/test/java</directory>
            <excludes>
                <exclude>**/*.java</exclude>
            </excludes>
        </testResource>
    </testResources>
    <plugins>
    ...
    </plugins>
</build>

Gradle Configuration:

Add this to your build.gradle:

sourceSets {
    test {
        resources {
            srcDir file('src/test/java')
            exclude '**/*.java'
        }
    }
}

Benefits:

• Keep .feature files alongside related .java test classes
• Easier to manage test artifacts (JSON, JS files) in one location
• No need to switch between src/test/java and src/test/resources folders

For more info on this topic, visit the Quickstart guide.

What Java version do I need?

Java 17 or higher is required as of Karate 1.4.0. Java 21+ is recommended for best performance.

# Check Java version (command line)
java -version
# Should show: java version "17.0.1" or higher

# Check in Karate test

* def javaVersion = java.lang.System.getProperty('java.version')
* print 'Java version:', javaVersion
* assert javaVersion.startsWith('17') || javaVersion.startsWith('21')

# Check available memory

* def runtime = java.lang.Runtime.getRuntime()
* print 'Max memory:', runtime.maxMemory() / 1024 / 1024, 'MB'

Version History:

• Karate 0.9.x - 1.3.x: Java 8+
• Karate 1.4.x+: Java 17+
• Future versions: Will likely require Java 21+

Why the upgrade?

• Modern JVM features and performance improvements
• Better security and maintenance
• Alignment with Spring Boot 3.x and other modern frameworks
• New language features for better code quality

Can I use Karate with Node.js projects?

Absolutely! Karate provides multiple ways to integrate with Node.js projects:

# Option 1: NPM CLI installation
npm install -g @karatelabs/karate-cli

# Run tests directly
karate test.feature
karate --threads 4 src/test/features

# Option 2: Local project installation
npm install --save-dev @karatelabs/karate-cli

# Add to package.json scripts
"scripts": {
  "test:api": "karate src/test/features",
  "test:api:parallel": "karate --threads 4 src/test/features",
  "test:api:env": "karate --env staging src/test/features"
}

# Option 3: Docker approach (no Java installation needed)
docker run --rm -v $(pwd):/workspace karatelabs/karate:latest

# Option 4: GitHub Actions with Java
- uses: actions/setup-java@v3
  with:
    java-version: '17'
- run: npm run test:api

Advantages for Node.js developers:

• No need to learn Java
• Integrates with npm scripts
• Works with existing CI/CD pipelines
• Can test Node.js APIs alongside frontend tests

Example project structure:

my-node-project/
├── package.json
├── src/
│   └── app.js
├── test/
│   ├── unit/           # Jest/Mocha tests
│   └── api/            # Karate tests
│       ├── karate-config.js
│       └── features/
│           └── user-api.feature
└── karate-reports/     # Generated reports

How do I set up VS Code for Karate?

1. Install the official Karate extension from the marketplace
2. Open a .feature file
3. You'll get syntax highlighting, auto-completion, and the ability to run tests directly from the editor

GET/vscode/extension/karatelabs.karate

Official Karate VS Code Extension - syntax highlighting, test execution, debugging

Writing Tests

How do I handle authentication?

Common authentication patterns:

Background:
  * url 'https://api.example.com'
  # Login and get token
  * path 'auth/login'
  * request { username: 'user', password: 'pass' }
  * method POST
  * status 200
  * def authToken = response.token

Scenario: Use authenticated endpoint
Given path 'protected-resource'
And header Authorization = 'Bearer ' + authToken
When method GET
Then status 200

How do I test GraphQL APIs?

Scenario: GraphQL Query
  Given url 'https://api.example.com/graphql'
  And text query =
  """
  query GetUser($id: ID!) {
    user(id: $id) {
      id
      name
      email
    }
  }
  """
  And request { query: '#(query)', variables: { id: '123' } }
  When method POST
  Then status 200
  And match response.data.user.name == '#string'

Can I test file uploads?

Yes, Karate handles multipart file uploads:

Given path 'upload'
And multipart file myFile = { read: 'test-file.pdf', filename: 'test.pdf', contentType: 'application/pdf' }
And multipart field message = 'Test upload'
When method POST
Then status 200

Data Management

How do I read test data from files?

# Read JSON data
* def userData = read('test-data/users.json')
* def user = userData[0]

# Read CSV data
* def csvData = read('test-data/users.csv')

# Use in test
Given path 'users'
And request user
When method POST
Then status 201

Can I use databases in tests?

Yes, through Java interop or HTTP endpoints:

# Via database HTTP service
Given url 'http://localhost:8080/db'
And path 'query'
And request { sql: 'SELECT * FROM users WHERE id = ?', params: [123] }
When method POST
Then status 200
And def dbResult = response.data[0]

Test Execution

How do I run tests in parallel?

@Test
public void testParallel() {
    Results results = Runner.path("classpath:features")
            .tags("@regression")
            .parallel(5); // 5 parallel threads

    assertEquals(0, results.getFailCount());
}

How do I skip tests conditionally?

* def skipTest = karate.env == 'prod'
* karate.abort(skipTest)

Scenario: Development only test
  # This test will be skipped in production
  Given path 'debug/endpoint'
  When method GET
  Then status 200

Can I generate test reports?

Yes, Karate automatically generates detailed HTML reports:

• Location: target/karate-reports/
• Features: Timeline view, detailed logs, pass/fail statistics
• Formats: HTML, JSON, JUnit XML

Performance & Mock Testing

Can I do performance testing?

Yes, Karate integrates with Gatling for performance testing:

@Test
void performanceTest() {
    PerfHook hook = new PerfHook("classpath:perf/load-test.js");
    Results results = Runner.path("classpath:features/api")
            .hook(hook)
            .parallel(10);
}

How do I create mock services?

Feature: User Mock Service

Background:
* def port = karate.start('user-mock.feature').port
* url 'http://localhost:' + port

Scenario: Mock returns user data
Given path 'users', 1
When method GET
Then status 200
And match response == { id: 1, name: 'John Doe' }

Troubleshooting

My tests are failing intermittently

Common causes and solutions:

1. Timing Issues: Add waits or increase timeouts

   * configure readTimeout = 30000
   * retry until responseStatus == 200

2. Test Data Dependencies: Ensure tests can run independently

   * def uniqueId = java.util.UUID.randomUUID()

3. Environment Differences: Use proper configuration management

   // karate-config.js
   if (env === 'ci') {
     config.readTimeout = 60000;
   }

How do I debug failing tests?

Background:
  * configure logPrettyRequest = true
  * configure logPrettyResponse = true
  * configure printEnabled = true

Scenario: Debug failing test
Given url 'https://api.example.com'
And path 'users', 1
When method GET
* print 'Response:', response
Then status 200

Tests work locally but fail in CI

Common solutions:

1. Environment Configuration: Ensure CI uses correct environment

   - name: Run Tests
     run: mvn test -Dkarate.env=ci

2. Timeouts: Increase timeouts for slower CI environments

3. Dependencies: Ensure all required services are running

4. Data: Use test-specific data or mocks

Integration & Advanced Topics

Can I integrate with Cucumber reports?

Yes, Karate generates Cucumber-compatible JSON:

Results results = Runner.path("classpath:features")
        .outputCucumberJson(true)
        .parallel(5);

How do I call Java code from Karate?

* def JavaUtils = Java.type('com.example.utils.TestUtils')
* def result = JavaUtils.processData('input-data')
* match result == 'expected-output'

# Call static methods
* def uuid = java.util.UUID.randomUUID() + ''

Can I use custom assertions?

Yes, create JavaScript functions:

// In karate-config.js
function customAssert(actual, expected) {
  // Your custom logic here
  return actual.toLowerCase() === expected.toLowerCase();
}

// Return in config
return { customAssert: customAssert };

# Use in tests
* assert customAssert(response.name, 'JOHN DOE')

Getting Help

Where can I get support?

Community Support (Free):

• 💬 Discord: Join our community - Most active, fastest response
• 📚 Stack Overflow: Search karate tag - Great for searchable Q&A
• 🐛 GitHub Issues: Report bugs - Bug reports and feature requests
• 📖 Documentation: This comprehensive guide with examples
• 📺 YouTube: Video tutorials
• 🌐 Examples Repository: karate-examples

Professional Support:

• 🏢 Enterprise Support: Karate Labs - SLA-backed support
• 🎓 Training Services: Corporate training and workshops
• 🔧 Consulting: Architecture reviews and implementation guidance
• 📞 Priority Support: Direct access to core team

When Asking for Help:

1. Provide context: Karate version, Java version, OS
2. Include code: Minimal reproduction example
3. Share errors: Full error messages and stack traces
4. Describe expected: What you're trying to achieve
5. Show attempts: What you've already tried

How do I contribute to Karate?

Ways to Contribute:

1. Code Contributions:

   • Fork the GitHub repository
   • Create feature branch: git checkout -b feature/my-improvement
   • Write tests for your changes
   • Follow the existing code style
   • Submit pull request with clear description

2. Documentation Improvements:

   • Fix typos or unclear explanations
   • Add examples for complex scenarios
   • Create video tutorials

3. Community Support:

   • Answer questions on Discord/Stack Overflow
   • Help newcomers get started
   • Share best practices and patterns

4. Testing & Feedback:

   • Test beta releases
   • Provide feedback on new features
   • Report bugs with detailed reproduction steps

Is Karate suitable for enterprise use?

Absolutely! Karate is widely adopted by Fortune 500 companies and large enterprises:

Enterprise Benefits:

• ✅ Robust: Battle-tested in production environments with high transaction volumes
• ✅ Scalable: Parallel execution, distributed testing, and cloud-native CI/CD integration
• ✅ Maintainable: Human-readable tests that reduce training overhead
• ✅ Comprehensive: Single tool eliminates tool sprawl (API + UI + Performance + Mocks)
• ✅ Secure: Built-in support for enterprise security patterns (OAuth, SAML, mutual TLS)
• ✅ Compliant: Detailed reporting for audit and compliance requirements
• ✅ Cost-effective: Reduces licensing costs compared to commercial alternatives

Success Metrics from Enterprise Users:

• 70% reduction in test automation development time
• 90% improvement in test maintainability
• 50% faster defect detection
• 80% reduction in cross-team training time

Enterprise Support Options:

• 🏢 Professional Services: Architecture design, implementation, training
• 📞 Priority Support: Dedicated support channels with SLA guarantees
• 🎓 Corporate Training: Custom training programs for teams
• 🔧 Custom Development: Feature development for specific enterprise needs

Advanced Topics

What are common Karate anti-patterns to avoid?

Anti-patterns and Better Alternatives:

1. ❌ Overusing Background for test data

   # DON'T - Heavy setup in Background
   Background:
     * call read('create-100-users.feature')
     * call read('setup-complex-data.feature')

   ✅ Better: Use callonce for expensive setup

   Background:
     * def testData = callonce read('lightweight-setup.feature')

2. ❌ Testing implementation details instead of behavior

   # DON'T - Testing internal field names
   And match response.internal_user_id == '#string'

   ✅ Better: Test user-facing behavior

   # DO - Test meaningful business outcomes
   And match response.user.canAccessResource == true

3. ❌ Hardcoding environment-specific values

   # DON'T
   Given url 'https://prod-api.company.com'

   ✅ Better: Use configuration

   Given url baseUrl

4. ❌ Creating overly complex, monolithic tests

   # DON'T - One test doing everything
   Scenario: Complete application workflow
     # 50+ steps testing everything

   ✅ Better: Focused, single-responsibility tests

   Scenario: User can create account
     # 5-10 focused steps
   
   Scenario: User can place order
     # 5-10 focused steps

When should I NOT use Karate?

Karate might not be the best choice for:

1. Pure Unit Testing: Use JUnit/TestNG for Java unit tests
2. Frontend-only Testing: Use Cypress/Playwright for pure UI testing
3. Non-HTTP Protocols: Limited support for protocols other than HTTP/WebSocket
4. Real-time Performance Testing: Use dedicated tools like JMeter for high-volume load testing
5. Mobile App Testing: Limited mobile support, use Appium directly

Better Alternatives:

• Unit Tests: JUnit 5, TestNG, Jest
• UI-only Tests: Cypress, Playwright, Selenium
• Load Testing: JMeter, Artillery, k6
• Mobile Testing: Appium, Detox, Espresso

How does Karate handle different data formats?

# JSON (native support)
* def user = { name: 'John', age: 30 }
* def users = read('users.json')

# XML (native support)
* def xmlData = <user><name>John</name><age>30</age></user>
* def xmlFromFile = read('data.xml')
* match xmlData/user/name == 'John'

# CSV (built-in conversion)
* def csvData = read('users.csv')
* def firstUser = csvData[0]

# YAML (built-in conversion)
* def yamlConfig = read('config.yaml')
* match yamlConfig.database.host == '#string'

# Binary data
* def imageBytes = karate.readAsBytes('test-image.png')
* def base64Image = karate.base64(imageBytes)

# Text files
* def templateText = read('email-template.txt')
* def processedText = karate.replace(templateText, '{{name}}', 'John')

# Environment-specific data
* def config = read('config-' + karate.env + '.json')

# Dynamic data generation
* def generateTestData = function(count) {
  var data = [];
  for (var i = 0; i < count; i++) {
  data.push({ id: i, name: 'User' + i });
  }
  return data;
  }
* def testUsers = call generateTestData(5)

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Ready to dive deeper? Join our Discord community to discuss advanced use cases, check out our examples repository for real-world implementations, or explore our enterprise solutions for large-scale deployments.