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Version: Next

Preparing for v4


If you are already using Mocks Server v2.x you should migrate first from v2.x to v3.x, and then read this chapter to prepare migration to v4.x.


Even when v4 release is still not published, we are deprecating some things in v3 that will be removed in v4. While v4 is not released, every change in v3.x will be completely backward compatible, but users upgrading to next minor versions would probably receive alerts about usage of deprecated methods, etc.

So, every time you upgrade a minor version and receive a deprecation alert, you can come to this page and see how to adapt your code for the next major version, so you'll be able to prepare to it progressively and finally update to v4 without breaking changes.

Changes summary

The main breaking changes in v4.x will be:

  • Some core API methods will be removed. Read core API below for further info.
  • Legacy alerts object will be removed. Read alerts for further info.
  • Arguments received by the plugins. Read plugins below for further info.

Core API

  • core.tracer: The tracer object will be completely removed and using it from v3.2 produces an alert. You must use core.logger instead, which is already namespaced when passed to plugins and route middlewares. Read the logger API docs for further info.


  • The core.alerts getter in the core when created programmatically was different to the core.alerts property received in the plugins from v3.2 due to backward compatibility reasons. In v4 it will return an alerts instance in the first case too. In the first case, it was returning a plain alerts collection. So, if you are using a programmatic root core, you should start using core.alertsApi.customFlat to get the same values, because that alias will be maintained in v4. Note that, in the case of plugins, you should continue using the alerts property, which will not change in v4.
  • The addAlert and removeAlerts methods that were being passed to plugins were deprecated in v3.1, and they will be removed in v4. Plugins were receiving an alerts property in the core to be used instead, which was also available in the root programmatic core using core.alertsApi. Read the alerts API docs for further info.


Core property

In version 3.1 a core property was added to the argument passed to the plugins. From v3.2, the whole core API was passed as first argument, but with some methods specifically scoped for the plugin. The core property was also maintained for backward compatibility but using it produced an alert. So, in v4 the core property will be definitively removed.

V3 example:

class Plugin {
constructor({ loadMocks, core, loadRoutes, addAlert, removeAlerts }) {
// core property was almost an alias containing again all of the rest of properties received

V4 example:

class Plugin {
constructor({ loadMocks, loadRoutes, addAlert, removeAlerts }) {
// core property is no longer received