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Module uses library @tinkoff/mocker to add a mocker functionality to the tramvai app. Mocker will be available as papi route with path /mocker.


First, install @tramvai/module-mocker:

npm install @tramvai/module-mocker

Then, add your first mock to a new file mocks/my-api.js. In this file add export of object literal with the field api that should be specified as a name of environment variable for the API url that should be mocked:

module.exports = {
api: 'MY_API',
mocks: {
'GET /endpoint?foo=bar': {
status: 200,
headers: {},
payload: {
result: {
type: 'json',
value: {
a: 'b',

Add module to the project:

import { createApp } from '@tramvai/core';
import { MockerModule } from '@tramvai/module-mocker';

name: 'tincoin',
modules: [MockerModule],

Run app with env MOCKER_ENABLED, e.g.:

MOCKER_ENABLED="true" tramvai start tincoin

After that, all of the requests to MY_API in browser and on server will be automatically sent to mocker. In case mocker doesn't have a suitable mock the request, the request will be proxied to the original API.


Most of the mocker features are described in the lib documentation.

Module adds mocker middleware to papi route /mocker and replaces all of the env variables that were defined in mocks by links to the papi. After that all of the request to the original API are routed first to mocker that accepts requests from the client and the server side.

By default, all of the API that were defined mocks are mocked, but it might be overridden.

Mocker us enabled only when env variable MOCKER_ENABLED is defined.

Env variables replacement

Let's say app has env variable MY_API: and for that api some mock is defined.

The module can work locally, on dynamic stand, in test/stage environments. But this flexibility leads to the following problems when resolving path to the papi endpoint:

  1. On server we should execute requests with absolute path. In this case we know that app is always available at localhost that mean we can replace API env variables by urls like http://localhost:3000/tincoin/papi/mocker/MY_API/
  2. On client test stands we do not known the domain of the app. In this case we should make requests by relative urls that mean we can replace API env variables by urls like /tincoin/papi/mocker/MY_API/

Thanks to this env replacement we can redirect all of the request to the APIs to our mocker first automatically.

How to

Mock only specific API

By default, all of the API that has corresponding mock will be mocked. It might be overridden by passing list of the APIs to mock when initializing module:

config: async () => ({
apis: ['MY_API'],

Exported tokens

import { createToken } from '@tinkoff/dippy';
import type { Mocker, MockRepository } from '@tinkoff/mocker';

export interface MockerOptions {
apis: string[];

export const MOCKER = createToken<Mocker>('MOCKER');

export const MOCKER_REPOSITORY = createToken<MockRepository>('MOCKER_REPOSITORY', {
multi: true,

createToken<() => Promise<MockerOptions>>('MOCKER_CONFIGURATION');