Registry / testing / scenario-mock-server

scenario-mock-server

library1.2.0jsnpmunverified

Scenario Mock Server is a Node.js library for creating highly configurable mock servers driven by user-defined scenarios. Currently stable at version 1.2.0, it is actively maintained with regular minor and patch releases, recently adding features like scenario grouping in the UI and exposing request headers to response functions. Key differentiators include an integrated web UI for dynamic scenario selection, a 'cookie mode' for multi-user isolation allowing each client to manage their own scenario state, and support for parallel testing through custom `sms-scenario-id` and `sms-context-id` headers, which bypass server-side scenario selection for specific requests. It can run as a standalone server or integrate into an existing Express application.

testing web-framework

npm install scenario-mock-server

github ↗package ↗

INSTALL

IMPORT

SIG · SCENARIO-MOCK-SERV

scenario-mock-server

testingjavascriptv1.2.0

Install

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Import

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Disk

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Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

run

✓ import { run } from 'scenario-mock-server';

✗ const { run } = require('scenario-mock-server');

While CommonJS `require` is supported, TypeScript projects and modern JavaScript environments should use ES Modules `import`.

createExpressApp

✓ import { createExpressApp } from 'scenario-mock-server';

✗ const { createExpressApp } = require('scenario-mock-server').createExpressApp;

Used for integrating the mock server into an existing Express application.

HttpMock

✓ import type { HttpMock } from 'scenario-mock-server';

✗ import { HttpMock } from 'scenario-mock-server';

This is a TypeScript type definition. Always use `import type` for types to avoid bundling issues and clarify intent.

This example initializes the mock server with two distinct scenarios, 'item' and 'cheese', for the '/api/test-me' endpoint, demonstrating basic setup and scenario definition.

import { run } from 'scenario-mock-server'; run({ scenarios: { item: [ { path: '/api/test-me', method: 'GET', response: { data: { blue: 'yoyo' } }, }, ], cheese: [ { path: '/api/test-me', method: 'GET', response: { data: { blue: 'cheese' } }, }, ], }, options: { port: process.env.MOCK_SERVER_PORT ? parseInt(process.env.MOCK_SERVER_PORT) : 3000, cookieMode: false } }); console.log('Scenario Mock Server running. Visit http://localhost:3000 to manage scenarios.');

Debug

Known issues

breakingThe package was renamed from `data-mocks-server` to `scenario-mock-server`. Projects upgrading or migrating from the old package name must update their `package.json` and all import/require statements.

fix

Update `npm install data-mocks-server` to `npm install scenario-mock-server` and change all code references from `data-mocks-server` to `scenario-mock-server`.

affects: >=1.0.0

gotchaCustom headers `sms-scenario-id` and `sms-context-id` for parallel testing are explicitly NOT supported when `cookieMode` is enabled. If you need per-request scenario selection, ensure `cookieMode` is set to `false` (default) or not configured.

fix

If parallel testing with headers is required, do not enable `cookieMode`. If `cookieMode` is necessary, manage scenarios and contexts via the UI or programmatically for individual users/sessions.

affects: >=1.0.0

breakingVersion 1.0.0 marked the first major release of the `scenario-mock-server` under its new name. While specific breaking changes from any pre-1.0.0 versions of `data-mocks-server` are not detailed in the release notes, users migrating from unversioned or pre-1.0.0 iterations of the original project should expect potential API shifts.

fix

Refer to the `scenario-mock-server` documentation for the latest API if migrating from older `data-mocks-server` versions. Review your mock definitions and server setup.

affects: >=1.0.0

Errors

Common errors & fixes

Error: listen EADDRINUSE: address already in use :::3000

The default port (3000) for the mock server is already occupied by another process.

fix

Specify a different port in the `options` object when calling `run()` or `createExpressApp()`, e.g., `{ options: { port: 3001 } }`.

ReferenceError: require is not defined

Attempting to use `require()` in an ECMAScript Module (ESM) context without proper configuration (e.g., `"type": "module"` in `package.json` but using `require`).

fix

Switch to `import { run } from 'scenario-mock-server';` syntax, or ensure your environment is configured for CommonJS modules, or use a build tool to transpile.

Scenario 'my-missing-scenario-id' not found or active for path '/api/data'

The requested scenario ID does not exist in your defined scenarios, or the server is not configured to select it.

fix

Verify the scenario ID spelling. Ensure the scenario is correctly defined in the `scenarios` object. If using the UI, select the correct scenario. If using `sms-scenario-id` header, confirm the header value matches an existing scenario group key.

Upgrade

Version history

1.2.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

13 hits · last 30 days

node

Resources

githubhttps://github.com/kenneth-gray/scenario-mock-server ↗

packagehttps://www.npmjs.com/package/scenario-mock-server ↗