🎉 Mock Config Server

tool that easily and quickly imitates server operation, create full fake api in few steps

Install

Install with npm or yarn

``bash
$ npm i mock-config-server --save --dev

or

$ yarn add mock-config-server --dev
`

🦉 Philosophy

🎉 Mock Config Server it is a tool that, easily, quickly simulates the work of a server. The main difference from solutions such as json-server and mock-service-worker is the ease of filling in data and flexible emulation of any and usual cases. Our goal is to create a simple and flexible system for users, with the help of which they can create, test, and support their products.

Features

- TypeScript support out of the box - full typed package
- Full Rest Api support - using simple configs of a certain format, you can easily simulate rest operation of servers
- GraphQL support - using simple configs of a certain format, you can easily simulate graphlql operation of servers
- Database - use mock database with all CRUD operations
- CORS setup - turn on and off CORS, fully customizable when CORS is turned on
- Support for any kind of static - server can return any type of static file if needed. Images, HTML, CSS, JSON, etc

Usage

Install 🎉 Mock Config Server with npm or yarn

`bash
$ npm i mock-config-server --save --dev

or

$ yarn add mock-config-server --dev
`

Create a mock-server.config.js file with server configuration

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'get',
routes: [{ data: { emoji: '🦁', name: 'Nursultan' } }]
}
]
}
];

export default flatMockServerConfig;
`

Start 🎉 Mock Config Server

`bash
$ npx mock-config-server
`

> If the package is already installed you can use short command mcs

🎭 Parameters for mock-server.config.(js|ts)

$3

- staticPath? {StaticPath} entity for working with static files, read
- interceptors? {Interceptors} functions to change request or response parameters, read
- cors? {Cors} CORS settings object (default: CORS is turn off), read
- port? {number} server port (default: 31299)
- baseUrl? {string} part of the url that will be substituted at the beginning of the request url (default: '/')
- database? Database config for mock requests read
- data {Object | string} initial data for database
- routes? {Object | string} map of custom routes for database

$3

- name {string} name of component
- baseUrl? {string} part of the url that will be substituted at the beginning of rest request url (default: '/')
- configs {Array} configs for mock requests, read
- interceptors? {Interceptors} functions to change request or response parameters, read

$3

Configs are the fundamental part of the mock server. These configs are easy to fill and maintain. Config entities is an object with which you can emulate various application behaviors. You can specify headers | cookies | query | params | body for Rest request or headers | cookies | query | variables for GraphQL request to define what contract data you need to get. Using this mechanism, you can easily simulate the operation of the server and emulate various cases

#### Rest request config

Every route must be configured to handle response content in one of three ways: data or queue or file.

- path string | RegExp request path
- method 'get' | 'post' | 'delete' | 'put' | 'patch' | 'options' rest api method
- routes RestRouteConfig[] request routes
- data? any mock data of request
- queue? Array<{ time?: number; data: any}> queue for polling with opportunity to set time for each response
- file? string path to file for return in response
- settings? Settings settings for route (polling on/off, etc.)
- entities? Object object that helps in data retrieval
- interceptors? Interceptors functions to change request or response parameters, read
- interceptors? Interceptors functions to change request or response parameters, read

##### Rest example

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'get',
routes: [
{
entities: {
headers: { 'name-header': 'Nursultan' }
},
data: { emoji: '🦁', name: 'Nursultan' }
},
{
entities: {
headers: { 'name-header': 'Dmitriy' }
},
data: { emoji: '☄', name: 'Dmitriy' }
}
]
}
]
}
];

export default flatMockServerConfig;
`

Now you can make a request with an additional header and get the desired result

`javascript
fetch('http://localhost:31299/api/user', {
headers: {
'name-header': 'Nursultan',
'Content-Type': 'application/json'
}
})
.then((response) => response.json())
.then((data) => console.log(data)); // { emoji: '🦁', name: 'Nursultan' }
`

#### GraphQL request config

Every route must be configured to handle response content in one of two ways: data or queue.

- operationType query | mutation graphql operation type
- operationName? string | RegExp graphql operation name
- query?: string graphql query as string
- routes GraphQLRouteConfig[] request routes
- data? any mock data of request
- queue? Array<{ time?: number; data: any}> queue for polling with opportunity to set time for each response
- settings? Settings settings for route (polling on/off, etc.)
- entities? Object object that helps in data retrieval
- interceptors? Interceptors functions to change request or response parameters, read
- interceptors? Interceptors functions to change request or response parameters, read

> Every graphql config should contain operationName or query or both of them

##### GraphQL example

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/graphql'
},
{
configs: [
{
operationType: 'query',
operationName: 'GetUser',
routes: [
{
entities: {
headers: { 'name-header': 'Nursultan' }
},
data: { emoji: '🦁', name: 'Nursultan' }
},
{
entities: {
headers: { 'name-header': 'Dmitriy' }
},
data: { emoji: '☄', name: 'Dmitriy' }
}
]
}
]
}
];

export default flatMockServerConfig;
`

Now you can make a request with an additional header and get the desired result

`javascript
const body = JSON.stringify({
query: 'query GetUser { name }'
});

fetch('http://localhost:31299/graphql', {
method: 'POST',
headers: {
'name-header': 'Nursultan',
'Content-Type': 'application/json'
},
body
})
.then((response) => response.json())
.then((data) => console.log(data)); // { emoji: '🦁', name: 'Nursultan' }
`

#### Entity descriptors

If you need more complex logic for matching entities, you can use entity descriptors.
Descriptor is an object with checkMode and value fields that describe how the correctness of the actual entity is calculated.

Allowed checkModes

- equals - checks actual value for equality with descriptor value (default).
- notEquals - checks actual value for non-equality with descriptor value.
- exists - checks actual value for existence i.e. any value.
- notExists - checks actual value for non-existence i.e. undefined value.
- includes - checks actual value for including with descriptor value.
- notIncludes - checks actual value for non-including with descriptor value.
- startsWith - checks actual value for starting with descriptor value.
- notStartsWith - checks actual value for non-starting with descriptor value.
- endsWith - checks actual value for ending with descriptor value.
- notEndsWith - checks actual value for non-ending with descriptor value.
- regExp - checks actual value with descriptor regExp.
- function - checks actual value with descriptor function.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'get',
routes: [
{
entities: {
headers: {
// 'name-header' is 'Dmitriy'
'name-header': {
checkMode: 'equals',
value: 'Dmitriy'
},
// check for 'equals' if descriptor not provided
// i.e. it is the same as role: { checkMode: 'equals', value: 'developer' }
role: 'developer'
},
cookies: {
// any 'token' cookie
token: {
checkMode: 'exists'
},
// 'someSecretToken' cookie can be '123-abc' or '456-abc' for example
someSecretToken: {
checkMode: 'regExp',
value: /^\d\d\d-abc$/
}
}
},
data: 'Some user data for Dmitriy'
}
]
}
]
}
];

export default flatMockServerConfig;
`

#### Descriptor _oneOf_ property

For checkMode with the value property (all checkMode options except exists and notExists) you can use an array as value.
Mock server will find matches by iterating through the array until some match is found.
To be able to use this functionality you need to explicitly set oneOf: true property in descriptor object.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'post',
routes: [
{
entities: {
// if body equals to { key1: 'value1' } OR { key2: 'value2' } then mock-config-server return 'Some user data 1'
body: {
checkMode: 'equals',
value: [{ key1: 'value1' }, { key2: 'value2' }],
oneOf: true
}
},
data: 'Some user data 1'
},
{
entities: {
// if body equals to [{ key1: 'value1' }, { key2: 'value2' }] then mock-config-server return 'Some user data 2'
// NO oneOf => array processed entirely
body: {
checkMode: 'equals',
value: [{ key1: 'value1' }, { key2: 'value2' }]
}
},
data: 'Some user data 2'
}
]
}
]
}
];

export default flatMockServerConfig;
`

#### Function check mode

function checkMode is the most powerful way to describe your entities logic, but in most cases you will be fine using other checkModes.

Function value has the following signature (actualValue, checkFunction) => boolean.
Return true if actualValue matches your logic or false otherwise.

You can use the checkFunction from second argument if you want to describe your logic in a more declarative way.
checkFunction has the following signature (checkMode, actualValue, descriptorValue?) => boolean.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/posts/:postId',
method: 'post',
routes: [
{
entities: {
params: {
postId: {
checkMode: 'function',
value: (actualValue) => +actualValue >= 0 && +actualValue <= 50
},
},
cookies: {
authToken: {
checkMode: 'function',
value: (actualValue, checkFunction) =>
checkFunction('equals', actualValue, 123) ||
checkFunction('startsWith', actualValue, 2)
}
}
},
data: 'Some user data'
}
]
}
]
}
];

module.exports = flatMockServerConfig;
`

##### Using descriptors for part of REST body or GraphQL variables

If you want to check a deep nested property of your body or variables via descriptor you can use flatten object style. In this case server will check every field in entity with corresponding actual field. I.e. you can use descriptors only for properties of entity object (not for properties of nested objects).

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/users',
method: 'post',
routes: [
{
entities: {
body: {
// if body has properties like { user: { name: 'Sergey' } } OR { 'user.name': 'Sergey' } then mock-config-server return data
'user.name': {
checkMode: 'equals',
value: 'Sergey'
}
}
},
data: 'user.name in body is "Sergey"'
}
]
}
]
}
];

export default flatMockServerConfig;
`

You can also use descriptor for whole body or variables entity.

> When you use 'equals'/'notEquals' check mode for whole body or variables mock-config-server is strictly compare entity and actual value. It means that you must specify ALL properties from actual body or variables.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/users',
method: 'post',
routes: [
{
entities: {
body: {
// if actual body contains some extra property(-ies) then this entity won't match
checkMode: 'equals',
value: {
user: {
name: 'Sergey',
emoji: '🐘',
roles: ['developer', 'moderator']
}
}
}
},
data: 'your body is strictly equals object from body entity value'
}
]
}
]
}
];

export default flatMockServerConfig;
`

#### File responses

Rest routes support paths to files. If a route is matched, the server will send data from the file. If the file is not found, the server will return 404.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/files/settings',
method: 'get',
routes: [
{
file: './settings.json'
}
]
}
]
}
];

export default flatMockServerConfig;
`

> If the file path is absolute, then this path will be used as is. If the file path is relative, it will be appended to the current working directory.

If the file exists, response interceptors will receive file descriptor as the data argument:

File descriptor is an object with path and file fields that describe file location and file content.

- path string path to the file. Same as file passed in route
- file Buffer file content as binary buffer

> Note to return file descriptor from interceptor. Server will send a buffer from data.file with corresponding Content-Type and Content-Disposition headers.
> If you return invalid file descriptor, server will send it as json data.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/files/settings',
method: 'get',
routes: [
{
file: './settings.json',
interceptors: {
response: (data) => {
const { file, path } = data;
const buffer = file; // some logic with buffer
fs.writeFileSync(path, buffer); // rewrite ./settings.json file on disk with new content
return { path, file: buffer };
}
}
}
]
}
]
}
];

export default flatMockServerConfig;
`

> Any changes to the data will not affect the file on disk unless you manually rewrite it.

> If you return a new path from interceptor, server will send file corresponding to this path or 404 error otherwise.

#### Polling

Routes support polling for data. To add polling for data, you must specify the polling setting and use queue property instead of data or file.

queue is an array containing data or file that should be returned in order.

> After receiving the last value from polling, the queue is reset and the next request will return the first value from the queue.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'get',
routes: [
{
settings: { polling: true },
queue: [
{ data: { emoji: '🦁', name: 'Nursultan' } },
{ data: { emoji: '☄', name: 'Dmitriy' } },
{ file: './users/Sergey.json' }
]
}
]
}
]
}
];

export default flatMockServerConfig;
`

Using the additional time properties in milliseconds, you can specify how much time certain data should be returned

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/user',
method: 'get',
routes: [
{
settings: { polling: true },
queue: [
{ time: 5000, data: { emoji: '🦁', name: 'Nursultan' } },
{ data: { emoji: '☄', name: 'Dmitriy' } }
]
}
]
}
]
}
];

export default flatMockServerConfig;
`

#### Static Path

Entity for connecting statics to the server, like HTML, JSON, PNG, etc.

- string path to your static files
- Object<{prefix, path}
- prefix string path prefix for request
- path string path to your static files
- Array>

#### Cors

Object with settings for CORS. You can flexibly configure the required origin, methods, headers, credentials, maxAge for the entire server. If you do not specify CORS settings, then it will be disabled.

- origin string | RegExp | Array | Function | Promise available origins from which requests can be made
- methods? Array available methods (default: GET,OPTIONS,PUT,PATCH,POST,DELETE)
- allowedHeaders? Array allowed headers (default: *)
- exposedHeaders? Array exposed headers (default: *)
- credentials? boolean param tells browsers whether to expose the response to the frontend JavaScript code (default: true)
- maxAge? number how long the results can be cached (default: 3600)

#### Interceptors

Functions to change request or response parameters

- request? (params) => void
- response? (data, params) => any

> request interceptors (except interceptor for route) are called regardless of whether the server found a route match or not. So changes in request interceptors can affect whether the server finds the route or not

##### Request

- params
- request request object
- setDelay (delay) => Promise
- delay number milliseconds of delay time
- getHeader (field) => string | number | string[] | undefined
- field string name of response header
- getHeaders () => Record
- getCookie (name) => string | undefined
- name string name of cookie
- log (logger) => Partial logger function read
- logger Logger | undefined logger options

##### Response

- data any mock data of request
- params
- request request object
- response response object
- setDelay (delay) => Promise
- delay number milliseconds of delay time
- setStatusCode (statusCode) => void
- statusCode number status code for response
- setHeader (field, value) => void
- field string name of response header
- value string | string[] | undefined value of response header
- appendHeader (field, value) => void
- field string name of response header
- value string | string[] | undefined value of response header
- getHeader (field) => string | number | string[] | undefined
- field string name of response header
- getHeaders () => Record
- setCookie (name, value, options) => void
- name string name of cookie
- value string value of cookie
- options CookieOptions | undefined cookie options (like path, expires, etc.)
- getCookie (name) => string | undefined
- name string name of cookie
- clearCookie (name, options) => void
- name string name of cookie
- options CookieOptions | undefined cookie options (like path, expires, etc.)
- attachment (filename) => void
- filename string name of file in 'Content-Disposition' header
- log (logger) => Partial logger function read
- logger Logger | undefined logger options

#### Logger

You can log requests and responses using log function in any interceptor.

log has the following signature (logger?: Logger) => Partial.

logger parameter has the following optional properties

- options? LoggerOptions object map containing tokens to log. Keys is token names, values is boolean. true will add token into log, false will remove. If options property is not passed, following tokens will be logged
- Request
- type
- id
- timestamp
- method
- url
- Response
- type
- id
- timestamp
- method
- url
- statusCode
- data
- rewrite? (tokens: Partial) => void function to replace default console.dir(tokens, { depth: null }) appearance

log function returns object with logged token values

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/posts',
method: 'get',
routes: [
{
interceptors: {
request: ({ log }) => {
log({
// logs following object in terminal
options: {
// {
id: true, // id: 1,
type: true, // type: 'request',
timestamp: true, // timestamp: '31.12.2024, 23:59:59,999',
method: true, // method: 'GET',
url: true // url: 'http://localhost:31299/api/rest/posts/1'
} // }
});
},
response: (data, { log }) => {
log({
// logs following string in terminal
options: {
// response get: http://localhost:31299/api/rest/posts/1 => 200
type: true,
statusCode: true,
method: true,
url: true
},
rewrite: ({ type, statusCode, method, url }) => {
console.info(${type} ${method}: ${url} => ${statusCode});
}
});
return data;
}
}
}
]
}
]
}
];

export default flatMockServerConfig;
`

> By default, timestamp and method tokens are prettified.
> Timestamp transforms from UNIX-timestamp number to DD.MM.YYYY, HH:mm:ss,sss string.
> Method transforms from lower case to upper case.
> If rewrite function is used, those tokens will remain unformatted. You can format them as you need.

##### Logger tokens

- type? 'request' | 'response' type of log
- id? number unique id of request to reference request log with response log
- timestamp? number UNIX-timestamp in milliseconds
- method? 'get' | 'post' | 'delete' | 'put' | 'patch' | 'options' HTTP method
- url? string requested URL
- graphQLOperationType? 'query' | 'mutation' | null GraphQL operation type. null if request is not GraphQL
- graphQLOperationName? string GraphQL operation name. null if request is not GraphQL
- graphQLQuery? string GraphQL query. null if request is not GraphQL
- variables?: Record GraphQL variables. null if request is not GraphQL or variables is not passed
- headers? Record headers object
- cookies? Record cookies object
- query? Record query object
- params? Record params object
- body? any body

Response logger has additional tokens

- statusCode? number response status code
- data? any data returned to client

If you need to log specific properties in mapped entities (headers, cookies, query, params), use Record object instead of boolean.
In that case logger will use following logic:

- if some token is true, entity will be filtered by whitelist logic. _Only_ enabled ones will be logged.
- if all tokens is false, entity will be filtered by blacklist logic. All entities will be logged _except_ disabled ones.

> Whitelist logic have priority over blacklist if you pass true and false in same entity.

`javascript
/* @type {import('mock-config-server').FlatMockServerConfig} /
const flatMockServerConfig = [
{
baseUrl: '/api'
},
{
configs: [
{
path: '/posts',
method: 'get',
routes: [
{
interceptors: {
request: ({ log }) => {
log({
// whitelist. only query1 and query2 will be logged
options: {
query: {
query1: true,
query2: true
}
}
});
log({
// whitelist. only cookie1 and cookie2 will be logged
options: {
cookies: {
cookie1: true,
cookie2: true,
cookie3: false
}
}
});
log({
// blacklist. all headers will be logged except header1
options: {
headers: {
header1: false
}
}
});
}
},
data: {}
}
]
}
]
}
];

export default flatMockServerConfig;
`

Database

With mock-config-server you can create your own mock database with all CRUD operations

- data Object | string initial data for database
- routes? Object | string map of custom routes for database

$3

`javascript
const flatMockServerConfig = [
{
database: {
data: {
users: [{ id: 1, name: 'John' }],
settings: {
blocked: false
}
}
}
}
];
`

Now you have the following routes for requests

#### Collection routes

`
GET /users
POST /users
GET /users/1
PUT /users/1
PATCH /users/1
DELETE /users/1
`

#### Single routes

`
GET /settings
POST /settings
PUT /settings
PATCH /settings
`

> Collection routes created from arrays which all elements have unique(!) id. Other database parts become single routes.

Also, there are additional routes: /__db and /__routes

`
__db -> return data from database config
__routes -> return routes from database config
`

$3

`javascript
const flatMockServerConfig = [
{
database: {
data: {
users: [{ id: 1, name: 'John' }],
settings: {
blocked: false
}
},
routes: {
'/api/users/:id': '/users/:id',
'/*/my-settings': '/settings'
}
}
}
];
`

Now following routes will work correctly

`
/api/users/1 -> return data for /users/1
/some/custom/url/my-settings -> return data for /settings
`

Note some things:

- String routes should start with forward slash
- If you want to use id param in route then use only :id template
- You can use wildcard only for custom route, not for real route

$3

> Use . to access deep properties

`
GET /users?name=siberiacancode
GET /users?id=1&id=2
GET /users?author.name=siberiacancode
`

$3

> Use \_page and optionally \_limit to paginate returned data.

`
GET /users?_page=1
GET /users?_page=1&_limit=5
`

> \_limit is 10 by default

The returned data has the format:

`
{
_link: Link,
results: Data[]
}
`

In the Link header you'll get count, pages, next and prev links.

#### Link

- count number total count of elements
- pages number count of pages
- next string | null query string for next link
- prev string | null query string for prev link

$3

> Use \_sort and \_order, use . to access deep properties

`
GET /users?_sort=name
GET /users/1/transfers?_sort=id&_order=asc
GET /users?_sort=address.city&_order=desc
`

> \_order is 'asc' by default

For multiple fields:

`
GET /users?_sort=id&_order=desc&_sort=name&_order=asc
`

$3

> X-Total-Count header is included in the response

`
GET /users?_begin=20
GET /users?_begin=20&_end=30
`

Works exactly as slice, \_begin and \_end are optional

$3

> Add \_q parameter for search data, search can be done by strings and numbers

`
GET /users?_q=siberia
`

For multiple search

`
GET /users?_q=siberia&_q=24
`

$3

`javascript
const flatMockServerConfig = [
{
database: {
data: './data.json',
routes: './routes.json'
}
}
];
`

Instead of objects you can use paths to JSON files which contain needed data or routes

CLI usage

`
mcs [options]

Options:
--baseUrl, -b Set base url (default: '/')
--port, -p Set port (default: 31299)
--staticPath, -s Set static path
--config, -c Set path to config file (default: './mock-server.config.(?:ts|mts|cts|js|mjs|cjs)')
--watch, -w Enables server restart after config file changes (default: false)

--version, -v Show version number
--help, -h Show help

Examples:
mcs --baseurl /base/url --port 3000 --config ./path/to/config.ts -w
mcs --help
`

Init Command

The init command is used to initialize a new project or set up the initial configuration for a tool. It helps users get started with a new project by providing a streamlined setup process.

`
mcs init

Examples:
mcs init
mcs init --baseurl /base/url --port 3000
``

✨ Contributors

width="100;" alt="debabin" /> ☄️ debabin

width="100;" alt="MiaInturi" /> 👹 MiaInturi

width="100;" alt="RiceWithMeat" /> 🐘 RiceWithMeat

width="100;" alt="anv296" /> 🎱️ anv296

width="100;" alt="kvelian" /> 🌵 kvelian