How To - Create an expectation on the fly with MockServer

HowTo-MockServer-RegisterExpectationOnTheFly.js

const mockServerClient = require('mockserver-client').mockServerClient;

const initialExpectation = {
  'httpRequest': {
    'method': 'POST',
    'path': '/trigger',
    'body': {
      'value': 'example'
    }
  },
  'httpResponse': {
    'statusCode': 200,
    'body': JSON.stringify({
      'id': '12345'
    })
  }
};

const subsequentExpectation = {
  'httpRequest': {
    'method': 'GET',
    'path': '/resource',
    'queryStringParameters': {
      'id': '12345'
    }
  },
  'httpResponse': {
    'statusCode': 200,
    'body': JSON.stringify({
      'value': 'example'
    })
  }
};

mockServerClient('localhost', 1080)
  .mockAnyResponse(initialExpectation)
  .then(() => {
    console.log('Initial expectation registered.');
  })
  .catch((error) => {
    console.log('Error registering initial expectation:', error);
  });

mockServerClient('localhost', 1080)
  .mockResponseCallback((request) => {
    if (request.method === 'POST' && request.path === '/trigger' && request.body.value === 'example') {
      console.log('Initial request received.');

      const id = JSON.parse(request.body).id;

      const newExpectation = {
        'httpRequest': {
          'method': 'GET',
          'path': '/resource',
          'queryStringParameters': {
            'id': id
          }
        },
        'httpResponse': {
          'statusCode': 200,
          'body': JSON.stringify({
            'value': 'example'
          })
        }
      };

      return Promise.all([
        mockServerClient('localhost', 1080).mockAnyResponse(newExpectation),
        mockServerClient('localhost', 1080).verify(newExpectation)
      ])
        .then(() => {
          console.log('New expectation registered.');
          return {
            'statusCode': 200,
            'body': 'Initial response'
          };
        })
        .catch((error) => {
          console.log('Error registering new expectation:', error);
          return {
            'statusCode': 500,
            'body': 'Internal server error'
          };
        });
    } else {
      return {
        'statusCode': 404,
        'body': 'Not found'
      };