@swimlane/cy-mockapi

Easily mock your REST API in Cypress by putting responses in the fixtures directory tree.

Installation and Setup

npm install --save-dev @swimlane/cy-mockapi

Import and setup the plugin in cypress/plugins/index.js:

import { installPlugin } from '@swimlane/cy-mockapi/plugin'

module.exports = (on, config) => {
  installPlugin(on, config);
}

Import the Cypress commands in cypress/support/index.js

import '@swimlane/cy-mockapi/commands';

Usage

Add one or more folders in cypress/fixtures to act as the mock API. Within this folder add files with the naming scheme:

{API PATH}/{METHOD}.{EXT}

For example:

cypress/fixtures/mocks
                  └── user
                      ├── get.json
                      ├── post.json
                      └── messages
                          ├── get.json
                          ├── delete.json
                          └── put.json

In your test files:

describe('Some Feature', () => {
  beforeEach(() => {
    cy.server();

    cy.mockApi({
      apiPath: '/api/',
      mocksFolder: './mocks/',
      cache: true
    });
  });

  it('should do the thing', () => {
    // Your test code
  });
})

In this example, @swimlane/cy-mockapi will read the cypress/fixtures/mocks folder and stub responses to the API requests; functionally equivalent to:

cy.route('GET', '/api/user', 'fixture:mocks/user/get.json').as('GET:user');
cy.route('POST', '/api/user', 'fixture:mocks/user/post.json').as('POST:user');
cy.route('GET', '/api/user/messages', 'fixture:mocks/user/messages/get.json').as('GET:user/messages');
cy.route('DELETE', '/api/user/messages', 'fixture:mocks/user/messages/delete.json').as('DELETE:user/messages');
cy.route('PUT', '/api/user/messages', 'fixture:mocks/user/messages/put.json').as('PUT:user/messages');

Commands

cy.mockApi

Reads and (optionally) caches the mocksFolder tree and sets up stubs. Note that this does not read the fixtures themselves; instead it sets up the stubbing (internally using cy.route). cy.mockApi may be called multiple times to mock different sets of fixtures or combine sets of fixtures.

Options

• apiPath - The API root path to mock.
• mocksFolder - The fixtures folder to use.
• cache - Boolean to use caching (caching is per unique mocksFolder)

cy.logExtraApiCalls

Call cy.logExtraApiCalls(apiPath) after cy.mockApi to log requests and responses that are not stubbed by cy.mockApi. This is useful for capturing responses while building out your mock files.

cy.failExtraApiCalls

Call cy.failExtraApiCalls(apiPath) after cy.mockApi to log and fail on requests that are not stubbed by cy.mockApi.

Fixture files

Fixture files (located within mocksFolder) in general should be named {method}.{ext} (for now only json and txt are supported). The API path will be generated from the path as described in the example above.

Wildcard slugs

To match against a route with a wildcard create a directory named or containing __ (double underscore) in place of the wildcard (*). For example, to mock the response of a GET request to /api/user/*/profile, create the fixture user/__/profile/get.json.

Query string parameters

To match against Query string parameters create a directory or file containing -- (double hyphen) in place of the ?. For example, to mock the response of a GET request to /api/user?id=1, create fixture user--id=1/get.json or user/--id=1.get.json.

options files

For additional flexibility create options.json files within the apiPath. These files are read by cy.mockApi and passed to cy.route. For example, the following file:

[
  {
    "url": "user?userid=*",
    "response": "delete-user.json",
    "method": "DELETE",
    "alias": "deleteUser",
  }
]

will setup file following route and stubbing:

cy.route({
  url: '/api/user?userid=*',
  response: 'fx:mocks/delete-user.json',
  method: 'DELETE',
}).as('deleteUser');

See the Cypress Documentation for more details on the options available.

Acknowledgements

Inspired in part by https://github.com/namshi/mockserver.

Credits

cy-mockapi is a Swimlane open-source project; we believe in giving back to the open-source community by sharing some of the projects we build for our application. Swimlane is an automated cyber security operations and incident response platform that enables cyber security teams to leverage threat intelligence, speed up incident response and automate security operations.