HTTP Request Mock
This module intercepts outgoing HTTP requests made by Drupal's http_client service during testing. It allows custom plugins to provide mocked responses for these requests, preventing actual external calls and enabling more reliable functional testing.
Inspired by Danny Sipos's (Upchuk) article: https://www.webomelette.com/simple-guzzle-api-mocking-functional-testing...
Description
When running tests, you don't want to perform external HTTP requests while you still want to test code that consumes such webservices. This module intercepts the requests made by the Drupal http_client service and allows a plugin to respond with a mocked response.
Usage
In order to mock a webservice, you'll need to create a service mock plugin. Such a plugin implements the ServiceMockPluginInterface. The plugin manager will pickup the first plugin that matches the HTTP request and will call the plugin's ::getResponse() method. Note that several plugins may qualify for the same request, but you can specify a weight in plugin's attribute so that such plugins are prioritized.
Implement one or more plugins for each webservice that you want to mock. In your tests, enable this module, and the modules that are shipping such plugins. This module ships a testing plugin that intercepts all outgoing HTTP requests made to example.com.
In some cases, tests may narrow the list of plugins to a limited set. Such tests should pass an array of plugin IDs to the http_request_mock.allowed_plugins state variable. Leaving this variable empty or not set, will allow all plugins to apply to the following outgoing HTTP requests.