qe-contract-testing

Testing & Quality

Consumer-driven contract testing for APIs including REST, GraphQL, and event-driven systems with schema validation.

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QE Contract Testing

Purpose

Guide the use of v3's contract testing capabilities including consumer-driven contracts, schema validation, backward compatibility checking, and API versioning verification.

Activation

When testing API contracts
When validating schema changes
When checking backward compatibility
When testing GraphQL APIs
When verifying event schemas

Quick Start

# Generate contract from API
aqe contract generate --api openapi.yaml --output contracts/

# Verify provider against contracts
aqe contract verify --provider http://localhost:3000 --contracts contracts/

# Check breaking changes
aqe contract breaking --old api-v1.yaml --new api-v2.yaml

# Test GraphQL schema
aqe contract graphql --schema schema.graphql --operations queries/

Agent Workflow

// Contract generation
Task("Generate API contracts", `
  Analyze the REST API and generate consumer contracts:
  - Parse OpenAPI specification
  - Identify critical endpoints
  - Generate Pact contracts
  - Include example requests/responses
  Output to contracts/ directory.
`, "qe-api-contract")

// Breaking change detection
Task("Check API compatibility", `
  Compare API v2.0 against v1.0:
  - Detect removed endpoints
  - Check parameter changes
  - Verify response schema changes
  - Identify deprecations
  Report breaking vs non-breaking changes.
`, "qe-api-compatibility")

Contract Testing Types

1. Consumer-Driven Contracts (Pact)

await contractTester.consumerDriven({
  consumer: 'web-app',
  provider: 'user-service',
  contracts: 'contracts/web-app-user-service.json',
  verification: {
    providerBaseUrl: 'http://localhost:3000',
    providerStates: providerStateHandlers,
    publishResults: true
  }
});

2. Schema Validation

await contractTester.validateSchema({
  type: 'openapi',
  schema: 'api/openapi.yaml',
  requests: actualRequests,
  validation: {
    requestBody: true,
    responseBody: true,
    headers: true,
    statusCodes: true
  }
});

3. GraphQL Contract Testing

await graphqlTester.testContracts({
  schema: 'schema.graphql',
  operations: 'queries/**/*.graphql',
  validation: {
    queryValidity: true,
    responseShapes: true,
    nullability: true,
    deprecations: true
  }
});

4. Event Contract Testing

await contractTester.eventContracts({
  schema: 'events/schemas/',
  events: {
    'user.created': {
      schema: 'UserCreatedEvent.json',
      examples: ['examples/user-created.json']
    },
    'order.completed': {
      schema: 'OrderCompletedEvent.json',
      examples: ['examples/order-completed.json']
    }
  },
  compatibility: 'backward'
});

Breaking Change Detection

breaking_changes:
  always_breaking:
    - endpoint_removed
    - required_param_added
    - response_field_removed
    - type_changed

  potentially_breaking:
    - optional_param_removed
    - response_field_added
    - enum_value_removed

  non_breaking:
    - endpoint_added
    - optional_param_added
    - response_field_made_optional
    - documentation_changed

Contract Report

interface ContractReport {
  summary: {
    contracts: number;
    passed: number;
    failed: number;
    warnings: number;
  };
  consumers: {
    name: string;
    contracts: ContractResult[];
    compatibility: 'compatible' | 'breaking' | 'unknown';
  }[];
  breakingChanges: {
    type: string;
    location: string;
    description: string;
    impact: 'high' | 'medium' | 'low';
    migration: string;
  }[];
  deprecations: {
    item: string;
    deprecatedIn: string;
    removeIn: string;
    replacement: string;
  }[];
}

CI/CD Integration

contract_verification:
  consumer_side:
    - generate_contracts
    - publish_to_broker
    - can_i_deploy_check

  provider_side:
    - fetch_contracts_from_broker
    - verify_against_provider
    - publish_results

  pre_release:
    - check_breaking_changes
    - verify_all_consumers
    - update_compatibility_matrix

Pact Broker Integration

await contractTester.withBroker({
  brokerUrl: 'https://pact-broker.example.com',
  auth: { token: process.env.PACT_TOKEN },
  operations: {
    publish: true,
    canIDeploy: true,
    webhooks: true
  }
});

Coordination

Primary Agents: qe-api-contract, qe-api-compatibility, qe-graphql-tester Coordinator: qe-contract-coordinator Related Skills: qe-test-generation, qe-security-compliance