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HTTP server mocking and expectations library for Node.js

Nock can be used to test modules that perform HTTP requests in isolation.

For instance, if a module performs HTTP requests to a CouchDB server or makes HTTP requests to the Amazon API, you can test that module in isolation.

Table of Contents

• How does it work?
• Install
  • Node version support
• Usage
  • READ THIS! - About interceptors
  • Specifying hostname
  • Specifying path
  • Specifying request body
  • Specifying request query string
  • Specifying replies
    • Access original request and headers
    • Replying with errors
  • Specifying headers
    • Header field names are case-insensitive
    • Specifying Request Headers
    • Specifying Reply Headers
    • Default Reply Headers
    • Including Content-Length Header Automatically
    • Including Date Header Automatically
  • HTTP Verbs
  • Support for HTTP and HTTPS
  • Non-standard ports
  • Repeat response n times
  • Delay the response
    • Delay the connection
      • Technical Details
    • Delay the response body
      • Technical Details
  • Chaining
  • Scope filtering
  • Conditional scope filtering
  • Path filtering
  • Request Body filtering
  • Request Headers Matching
  • Optional Requests
  • Allowunmocked requests on a mocked hostname
• Expectations
  • .isDone()
  • .cleanAll()
  • .abortPendingRequests()
  • .persist()
  • .pendingMocks()
  • .activeMocks()
  • .isActive()
  • .clone()
• Restoring
• Activating
• Turning Nock Off (experimental!)
• Enable/Disable real HTTP requests
  • Disabling requests
  • Enabling requests
  • Resetting NetConnect
• Recording
  • dont_print option
  • output_objects option
  • enable_reqheaders_recording option
  • logging option
  • use_separator option
  • .removeInterceptor()
• Events
  • Global no match event
• Nock Back
  • Setup
    • Options
  • Usage
    • Options
      • Example
  • Modes
  • Verifying recorded fixtures
    • Example
• Common issues
  • Requests made by ES Modules are not intercepted
  • Axios
  • Memory issues with Jest
• Debugging
• Contributing
• Contributors
• Sponsors
• License

Nock works by overriding Node'shttp.request function. Also, it overrideshttp.ClientRequest too to cover for modules that use it directly.

$ npm install --save-dev nock

The latest version of nock supports all currently maintained Node versions, seeNode Release Schedule

Here is a list of past nock versions with respective node version support

On your test, you can setup your mocking object like this:

constnock=require('nock')constscope=nock('https://api.github.com').get('/repos/atom/atom/license').reply(200,{license:{key:'mit',name:'MIT License',spdx_id:'MIT',url:'https://api.github.com/licenses/mit',node_id:'MDc6TGljZW5zZTEz',},})

This setup says that we will intercept every HTTP call tohttps://api.github.com.

It will intercept an HTTPS GET request to/repos/atom/atom/license, reply witha status 200, and the body will contain a (partial) response in JSON.

When you setup an interceptor for a URL and that interceptor is used, it is removed from the interceptor list.This means that you can intercept 2 or more calls to the same URL and return different things on each of them.It also means that you must setup one interceptor for each request you are going to have, otherwise nock will throw an error because that URL was not present in the interceptor list.If you don’t want interceptors to be removed as they are used, you can use the.persist() method.

The request hostname can be a string, URL, or a RegExp.

constscope=nock('http://www.example.com').get('/resource').reply(200,'domain matched')

constscope=nock(newURL('http://www.example.com')).get('/resource').reply(200,'domain matched')

constscope=nock(/example\.com/).get('/resource').reply(200,'domain regex matched')

Note: You can choose to include or not the protocol in the hostname matching.

The request path can be a string, a RegExp or a filter function and you can use anyHTTP verb.

Using a string:

constscope=nock('http://www.example.com').get('/resource').reply(200,'path matched')

Using a regular expression:

constscope=nock('http://www.example.com').get(/source$/).reply(200,'path using regex matched')

Using a function:

constscope=nock('http://www.example.com').get(uri=>uri.includes('cats')).reply(200,'path using function matched')

You can specify the request body to be matched as the second argument to theget,post,put ordelete specifications. There are five types of second argument allowed:

String: nock will exact match the stringified request body with the provided string

nock('http://www.example.com').post('/login','username=pgte&password=123456').reply(200,{id:'123ABC'})

Buffer: nock will exact match the stringified request body with the provided buffer

nock('http://www.example.com').post('/login',Buffer.from([0xff,0x11])).reply(200,{id:'123ABC'})

RegExp: nock will test the stringified request body against the provided RegExp

nock('http://www.example.com').post('/login',/username=\w+/gi).reply(200,{id:'123ABC'})

JSON object: nock will exact match the request body with the provided object. In order to increase flexibility, nock also supports RegExp as an attribute value for the keys:

nock('http://www.example.com').post('/login',{username:'pgte',password:/.+/i}).reply(200,{id:'123ABC'})

Function: nock will evaluate the function providing the request body object as first argument. Return true if it should be considered a match:

nock('http://www.example.com').post('/login',body=>body.username&&body.password).reply(200,{id:'123ABC'})

In case you need to perform a partial matching on a complex, nested request body you should have a look at libraries likelodash.matches. Indeed, partial matching can be achieved as:

nock('http://www.example.com').post('/user',_.matches({address:{country:'US'}})).reply(200,{id:'123ABC'})

Nock understands query strings. Search parameters can be included as part of the path:

nock('http://example.com').get('/users?foo=bar').reply(200)

Instead of placing the entire URL, you can specify the query part as an object:

nock('http://example.com').get('/users').query({name:'pedro',surname:'teixeira'}).reply(200,{results:[{id:'pgte'}]})

Nock supports array-style/object-style query parameters. The encoding format matches with request module.

nock('http://example.com').get('/users').query({names:['alice','bob'],tags:{alice:['admin','tester'],bob:['tester'],},}).reply(200,{results:[{id:'pgte'}]})

AURLSearchParams instance can be provided.

constparams=newURLSearchParams({foo:'bar'})nock('http://example.com').get('/').query(params).reply(200)

Nock supports passing a function to query. The function determines if the actual query matches or not.

nock('http://example.com').get('/users').query(actualQueryObject=>{// do some compare with the actual Query Object// return true for matched// return false for not matchedreturntrue}).reply(200,{results:[{id:'pgte'}]})

To mock the entire url regardless of the passed query string:

nock('http://example.com').get('/users').query(true).reply(200,{results:[{id:'pgte'}]})

A query string that is alreadyURL encoded can bematched by passing theencodedQueryParams flag in the options when creating the Scope.

nock('http://example.com',{encodedQueryParams:true}).get('/users').query('foo%5Bbar%5D%3Dhello%20world%21').reply(200,{results:[{id:'pgte'}]})

You can specify the return status code for a path on the first argument of reply like this:

constscope=nock('http://myapp.iriscouch.com').get('/users/1').reply(404)

You can also specify the reply body as a string:

constscope=nock('http://www.google.com').get('/').reply(200,'Hello from Google!')

or as a JSON-encoded object:

constscope=nock('http://myapp.iriscouch.com').get('/').reply(200,{username:'pgte',email:'pedro.teixeira@gmail.com',_id:'4324243fsd',})

or even as a file:

constscope=nock('http://myapp.iriscouch.com').get('/').replyWithFile(200,__dirname+'/replies/user.json',{'Content-Type':'application/json',})

Instead of an object or a buffer you can also pass in a callback to be evaluated for the value of the response body:

constscope=nock('http://www.google.com').post('/echo').reply(201,(uri,requestBody)=>requestBody)

In Nock 11.x it was possible to invoke.reply() with a status code and afunction that returns an array containing a status code and body. (The statuscode from the array would take precedence over the one passed directly toreply.) This is no longer allowed. In Nock 12 and later, either call.reply() with astatus code and a function that returns the body, or call it with a singleargument: a function that returns an array containing both the status code andbody.

An asynchronous function that gets an error-first callback as its last argument also works:

constscope=nock('http://www.google.com').post('/echo').reply(201,(uri,requestBody,cb)=>{fs.readFile('cat-poems.txt',cb)// Error-first callback})

In Nock 11 and later, if an error is passed to the callback, Nock will rethrow it as a programmer error.In Nock 10 and earlier, the error was sent in the response body, with a 500 HTTP response status code.

You can also return the status code and body using just one function:

constscope=nock('http://www.google.com').post('/echo').reply((uri,requestBody)=>{return[201,'THIS IS THE REPLY BODY',{header:'value'},// optional headers]})

or, use an error-first callback that also gets the status code:

constscope=nock('http://www.google.com').post('/echo').reply((uri,requestBody,cb)=>{setTimeout(()=>cb(null,[201,'THIS IS THE REPLY BODY']),1000)})

A Stream works too:

constscope=nock('http://www.google.com').get('/cat-poems').reply(200,(uri,requestBody)=>{returnfs.createReadStream('cat-poems.txt')})

If you're using the reply callback style, you can access the original client request usingthis.req like this:

constscope=nock('http://www.google.com').get('/cat-poems').reply(function(uri,requestBody){console.log('path:',this.req.path)console.log('headers:',this.req.headers)// ...})

Note: Remember to use normalfunction in that case, as arrow functions are using enclosing scope forthis binding.

You can reply with an error like this:

nock('http://www.google.com').get('/cat-poems').replyWithError('something awful happened')

Error objects are allowed too:

nock('http://www.google.com').get('/cat-poems').replyWithError(Object.assign(newError('Connection refused'),{code:'ECONNREFUSED'}),)

Note: This will emit anerror event on therequest object, not the reply.

PerHTTP/1.1 4.2 Message Headers specification, all message headers are case insensitive and thus internally Nock uses lower-case for all field names even if some other combination of cases was specified either in mocking specification or in mocked requests themselves.

You can specify the request headers like this:

constscope=nock('http://www.example.com',{reqheaders:{authorization:'Basic Auth',},}).get('/').reply(200)

Or you can use a regular expression or function to check the header values. Thefunction will be passed the header value.

constscope=nock('http://www.example.com',{reqheaders:{'X-My-Headers':headerValue=>headerValue.includes('cats'),'X-My-Awesome-Header':/Awesome/i,},}).get('/').reply(200)

Ifreqheaders is not specified or ifhost is not part of it, Nock will automatically addhost value to request header.

If no request headers are specified for mocking then Nock will automatically skip matching of request headers. Since thehost header is a special case which may get automatically inserted by Nock, its matching is skipped unless it wasalso specified in the request being mocked.

You can also have Nock fail the request if certain headers are present:

constscope=nock('http://www.example.com',{badheaders:['cookie','x-forwarded-for'],}).get('/').reply(200)

When invoked with this option, Nock will not match the request if any of thebadheaders are present.

Basic authentication can be specified as follows:

constscope=nock('http://www.example.com').get('/').basicAuth({user:'john',pass:'doe'}).reply(200)

You can specify the reply headers like this:

constscope=nock('https://api.github.com').get('/repos/atom/atom/license').reply(200,{license:'MIT'},{'X-RateLimit-Remaining':4999})

Or you can use a function to generate the headers values. The function will bepassed the request, response, and response body (if available). The body willbe either a buffer, a stream, or undefined.

constscope=nock('http://www.headdy.com').get('/').reply(200,'Hello World!',{'Content-Length':(req,res,body)=>body.length,ETag:()=>`${Date.now()}`,})

You can also specify default reply headers for all responses like this:

constscope=nock('http://www.headdy.com').defaultReplyHeaders({'X-Powered-By':'Rails','Content-Type':'application/json',}).get('/').reply(200,'The default headers should come too')

Or you can use a function to generate the default headers values:

constscope=nock('http://www.headdy.com').defaultReplyHeaders({'Content-Length':(req,res,body)=>body.length,}).get('/').reply(200,'The default headers should come too')

When usinginterceptor.reply() to set a response body manually, you can have theContent-Length header calculated automatically.

constscope=nock('http://www.headdy.com').replyContentLength().get('/').reply(200,{hello:'world'})

NOTE: this does not work with streams or other advanced means of specifyingthe reply body.

You can automatically append aDate header to your mock reply:

constscope=nock('http://www.headdy.com').replyDate().get('/').reply(200,{hello:'world'})

Or provide your ownDate object:

constscope=nock('http://www.headdy.com').replyDate(newDate(2015,0,1)).get('/').reply(200,{hello:'world'})

Nock supports any HTTP verb, and it has convenience methods for the GET, POST, PUT, HEAD, DELETE, PATCH, OPTIONS and MERGE HTTP verbs.

You can intercept any HTTP verb using.intercept(path, verb [, requestBody [, options]]):

constscope=nock('http://my.domain.com').intercept('/path','PATCH').reply(304)

By default nock assumes HTTP. If you need to use HTTPS you can specify thehttps:// prefix like this:

constscope=nock('https://secure.my.server.com')// ...

You are able to specify a non-standard port like this:

constscope=nock('http://my.server.com:8081')

You are able to specify the number of times to repeat the same response.

NOTE: When request times is more than the number you specified, you will get an error before cleaning this interceptor.

nock('http://zombo.com').get('/').times(4).reply(200,'Ok')http.get('http://zombo.com/')// respond body "Ok"http.get('http://zombo.com/')// respond body "Ok"http.get('http://zombo.com/')// respond body "Ok"http.get('http://zombo.com/')// respond body "Ok"// This code will get an error with message:// Nock: No match for requesthttp.get('http://zombo.com/')// clean your interceptornock.cleanAll()http.get('http://zombo.com/')// real respond with zombo.com result

Sugar syntax

nock('http://zombo.com').get('/').once().reply(200,'Ok')nock('http://zombo.com').get('/').twice().reply(200,'Ok')nock('http://zombo.com').get('/').thrice().reply(200,'Ok')

To repeat this response for as long as nock is active, use.persist().

Nock can simulate response latency to allow you to test timeouts, race conditions, an other timing related scenarios.
You are able to specify the number of milliseconds that your reply should be delayed.

nock('http://my.server.com').get('/').delay(2000)// 2 seconds delay will be applied to the response body..reply(200,'<html></html>')

ThedelayConnection method’s behavior of emitting quick timeout events when the connection delay exceeds the request timeout is now deprecated. Please use thedelay function instead.

ThedelayBody is now deprecated. Please use thedelay function instead.

nock('http://my.server.com').get('/').delayBody(2000)// 2 seconds.reply(200,'<html></html>')

Following the'response' being emitted byClientRequest,Nock will register a timeout timer with the body delay value to delay real time before theIncomingMessage emits its first'data' or the'end' event.

You can chain behaviour like this:

constscope=nock('http://myapp.iriscouch.com').get('/users/1').reply(404).post('/users',{username:'pgte',email:'pedro.teixeira@gmail.com',}).reply(201,{ok:true,id:'123ABC',rev:'946B7D1C',}).get('/users/123ABC').reply(200,{_id:'123ABC',_rev:'946B7D1C',username:'pgte',email:'pedro.teixeira@gmail.com',})

You can filter the scope (protocol, domain or port) of nock through a function. The filtering function is accepted at thefilteringScope field of theoptions argument.

This can be useful if you have a node module that randomly changes subdomains to which it sends requests, e.g., the Dropbox node module behaves like this.

constscope=nock('https://api.dropbox.com',{filteringScope:scope=>/^https:\/\/api[0-9]*.dropbox.com/.test(scope),}).get('/1/metadata/auto/Photos?include_deleted=false&list=true').reply(200)

You can also choose to filter out a scope based on your system environment (or any external factor). The filtering function is accepted at theconditionally field of theoptions argument.

This can be useful if you only want certain scopes to apply depending on how your tests are executed.

constscope=nock('https://api.myservice.com',{conditionally:()=>true,})

You can also filter the URLs based on a function.

This can be useful, for instance, if you have random or time-dependent data in your URL.

You can use a regexp for replacement, just like String.prototype.replace:

constscope=nock('http://api.myservice.com').filteringPath(/password=[^&]*/g,'password=XXX').get('/users/1?password=XXX').reply(200,'user')

Or you can use a function:

constscope=nock('http://api.myservice.com').filteringPath(path=>'/ABC').get('/ABC').reply(200,'user')

Note thatscope.filteringPath is not cumulative: it should only be used once per scope.

You can also filter the request body based on a function.

This can be useful, for instance, if you have random or time-dependent data in your request body.

You can use a regexp for replacement, just like String.prototype.replace:

constscope=nock('http://api.myservice.com').filteringRequestBody(/password=[^&]*/g,'password=XXX').post('/users/1','data=ABC&password=XXX').reply(201,'OK')

Or you can use a function to transform the body:

constscope=nock('http://api.myservice.com').filteringRequestBody(body=>'ABC').post('/','ABC').reply(201,'OK')

If you don't want to match the request body you should omit thebody argument from the method function:

constscope=nock('http://api.myservice.com').post('/some_uri')// no body argument.reply(200,'OK')

If you need to match requests only if certain request headers match, you can.

constscope=nock('http://api.myservice.com')// Interceptors created after here will only match when the header `accept` equals `application/json`..matchHeader('accept','application/json').get('/').reply(200,{data:'hello world',}).get('/')// Only this interceptor will match the header value `x-my-action` with `MyFirstAction`.matchHeader('x-my-action','MyFirstAction').reply(200,{data:'FirstActionResponse',}).get('/')// Only this interceptor will match the header value `x-my-action` with `MySecondAction`.matchHeader('x-my-action','MySecondAction').reply(200,{data:'SecondActionResponse',})

You can also use a regexp for the header body.

constscope=nock('http://api.myservice.com').matchHeader('User-Agent',/Mozilla\/.*/).get('/').reply(200,{data:'hello world',})

You can also use a function for the header body.

constscope=nock('http://api.myservice.com').matchHeader('content-length',val=>val>=1000).get('/').reply(200,{data:'hello world',})

By default every mocked request is expected to be made exactly once, and until it is it'll appear inscope.pendingMocks(), andscope.isDone() will return false (seeexpectations). In many cases this is fine, but in some (especially cross-test setup code) it's useful to be able to mock a request that may or may not happen. You can do this withoptionally(). Optional requests are consumed just like normal ones once matched, but they do not appear inpendingMocks(), andisDone() will return true for scopes with only optional requests pending.

constexample=nock('http://example.com')example.pendingMocks()// []example.get('/pathA').reply(200)example.pendingMocks()// ["GET http://example.com:80/path"]// ...After a request to example.com/pathA:example.pendingMocks()// []example.get('/pathB').optionally().reply(200)example.pendingMocks()// []// You can also pass a boolean argument to `optionally()`. This// is useful if you want to conditionally make a mocked request// optional.constgetMock=optional=>example.get('/pathC').optionally(optional).reply(200)getMock(true)example.pendingMocks()// []getMock(false)example.pendingMocks()// ["GET http://example.com:80/pathC"]

If you need some request on the same host name to be mocked and some others toreally go through the HTTP stack, you can use theallowUnmocked option like this:

constscope=nock('http://my.existing.service.com',{allowUnmocked:true}).get('/my/url').reply(200,'OK!')// GET /my/url => goes through nock// GET /other/url => actually makes request to the server

Note: When applying{allowUnmocked: true}, if the request is made to the real server, no interceptor is removed.

Every time an HTTP request is performed for a scope that is mocked, Nock expects to find a handler for it. If it doesn't, it will throw an error.

Calls to nock() return a scope which you can assert by callingscope.done(). This will assert that all specified calls on that scope were performed.

Example:

constscope=nock('http://google.com').get('/').reply(200,'Hello from Google!')// do some stuffsetTimeout(()=>{// Will throw an assertion error if meanwhile a "GET http://google.com" was// not performed.scope.done()},5000)

You can callisDone() on a single expectation to determine if the expectation was met:

constscope=nock('http://google.com').get('/').reply(200)scope.isDone()// will return false

It is also available in the global scope, which will determine if all expectations have been met:

nock.isDone()

You can cleanup all the prepared mocks (could be useful to cleanup some state after a failed test) like this:

nock.cleanAll()

You can abort all current pending request like this:

nock.abortPendingRequests()

You can make all the interceptors for a scope persist by calling.persist() on it:

constscope=nock('http://example.com').persist().get('/').reply(200,'Persisting all the way')

Note that while a persisted scope will always intercept the requests, it is considered "done" after the first interception.

If you want to stop persisting an individual persisted mock you can callpersist(false):

constscope=nock('http://example.com').persist().get('/').reply(200,'ok')// Do some tests ...scope.persist(false)

You can also usenock.cleanAll() which removes all mocks, including persistent mocks.

To specify an exact number of times that nock should repeat the response, use.times().

If a scope is not done, you can inspect the scope to infer which ones are still pending using thescope.pendingMocks() function:

if(!scope.isDone()){console.error('pending mocks: %j',scope.pendingMocks())}

It is also available in the global scope:

console.error('pending mocks: %j',nock.pendingMocks())

You can see every mock that is currently active (i.e. might potentially reply to requests) in a scope usingscope.activeMocks(). A mock is active if it is pending, optional but not yet completed, or persisted. Mocks that have intercepted their requests and are no longer doing anything are the only mocks which won't appear here.

You probably don't need to use this - it mainly exists as a mechanism to recreate the previous (now-changed) behavior ofpendingMocks().

console.error('active mocks: %j',scope.activeMocks())

It is also available in the global scope:

console.error('active mocks: %j',nock.activeMocks())

Your tests may sometimes want to deactivate the nock interceptor.Once deactivated, nock needs to be re-activated to work.You can check if nock interceptor is active or not by usingnock.isActive().Sample:

if(!nock.isActive()){nock.activate()}

You can clone a scope by calling.clone() on it:

constscope=nock('http://example.test')constgetScope=scope.get('/').reply(200)constpostScope=scope.clone().post('/').reply(200)

You can restore the HTTP interceptor to the normal unmocked behaviour by calling:

nock.restore()

note 1: restore does not clear the interceptor list. Usenock.cleanAll() if you expect the interceptor list to be empty.

note 2: restore will also remove the http interceptor itself. You need to runnock.activate() to re-activate the http interceptor. Without re-activation, nock will not intercept any calls.

Only for cases where nock has been deactivated usingnock.restore(), you can reactivate the HTTP interceptor to start intercepting HTTP calls using:

nock.activate()

note: To check if nock HTTP interceptor is active or inactive, usenock.isActive().

You can bypass Nock completely by setting theNOCK_OFF environment variable to"true".

This way you can have your tests hit the real servers just by switching on this environment variable.

$ NOCK_OFF=true node my_test.js

By default, any requests made to a host that is not mocked will be executed normally. If you want to block these requests, nock allows you to do so.

For disabling real http requests.

nock.disableNetConnect()

So, if you try to request any host not 'nocked', it will throw aNetConnectNotAllowedError.

nock.disableNetConnect()constreq=http.get('http://google.com/')req.on('error',err=>{console.log(err)})// The returned `http.ClientRequest` will emit an error event (or throw if you're not listening for it)// This code will log a NetConnectNotAllowedError with message:// Nock: Disallowed net connect for "google.com:80"

For enabling any real HTTP requests (the default behavior):

nock.enableNetConnect()

You could allow real HTTP requests for certain host names by providing a string or a regular expression for the hostname, or a function that accepts the hostname and returns true or false:

// Using a stringnock.enableNetConnect('amazon.com')// Or a RegExpnock.enableNetConnect(/(amazon|github)\.com/)// Or a Functionnock.enableNetConnect(host=>host.includes('amazon.com')||host.includes('github.com'),)http.get('http://www.amazon.com/')http.get('http://github.com/')http.get('http://google.com/')// This will throw NetConnectNotAllowedError with message:// Nock: Disallowed net connect for "google.com:80"

A common use case when testing local endpoints would be to disable all but localhost, then add in additional nocks for external requests:

nock.disableNetConnect()// Allow localhost connections so we can test local routes and mock servers.nock.enableNetConnect('127.0.0.1')

When you're done with the test, you probably want to set everything back to normal:

nock.cleanAll()nock.enableNetConnect()

This is a cool feature:

Guessing what the HTTP calls are is a mess, especially if you are introducing nock on your already-coded tests.

For these cases where you want to mock an existing live system you can record and playback the HTTP calls like this:

nock.recorder.rec()// Some HTTP calls happen and the nock code necessary to mock// those calls will be outputted to console

Recording relies on intercepting real requests and responses and then persisting them for later use.

In order to stop recording you should callnock.restore() and recording will stop.

ATTENTION!: when recording is enabled, nock does no validation, nor will any mocks be enabled. Please be sure to turn off recording before attempting to use any mocks in your tests.

If you just want to capture the generated code into a var as an array you can use:

nock.recorder.rec({dont_print:true,})// ... some HTTP callsconstnockCalls=nock.recorder.play()

ThenockCalls var will contain an array of strings representing the generated code you need.

Copy and paste that code into your tests, customize at will, and you're done! You can callnock.recorder.clear() to remove already recorded calls from the array thatnock.recorder.play() returns.

(Remember that you should do this one test at a time).

In case you want to generate the code yourself or use the test data in some other way, you can pass theoutput_objects option torec:

nock.recorder.rec({output_objects:true,})// ... some HTTP callsconstnockCallObjects=nock.recorder.play()

The returned call objects have the following properties:

• scope - the scope of the call including the protocol and non-standard ports (e.g.'https://github.com:12345')
• method - the HTTP verb of the call (e.g.'GET')
• path - the path of the call (e.g.'/pgte/nock')
• body - the body of the call, if any
• status - the HTTP status of the reply (e.g.200)
• response - the body of the reply which can be a JSON, string, hex string representing binary buffers or an array of such hex strings (when handlingcontent-encoded in reply header)
• rawHeaders - the headers of the reply which are formatted as a flat array containing header name and header value pairs (e.g.['accept', 'application/json', 'set-cookie', 'my-cookie=value'])
• reqheader - the headers of the request

If you save this as a JSON file, you can load them directly throughnock.load(path). Then you can post-process them before using them in the tests. For example, to add request body filtering (shown here fixing timestamps to match the ones captured during recording):

nocks=nock.load(pathToJson)nocks.forEach(function(nock){nock.filteringRequestBody=(body,aRecordedBody)=>{if(typeofbody!=='string'||typeofaRecordedBody!=='string'){returnbody}constrecordedBodyResult=/timestamp:([0-9]+)/.exec(aRecordedBody)if(recordedBodyResult){constrecordedTimestamp=recordedBodyResult[1]returnbody.replace(/(timestamp):([0-9]+)/g,function(match,key,value){returnkey+':'+recordedTimestamp},)}else{returnbody}}})

Alternatively, if you need to pre-process the captured nock definitions beforeusing them (e.g. to add scope filtering) then you can usenock.loadDefs(path)andnock.define(nockDefs). Shown here is scope filtering for Dropbox nodemodule which constantly changes the subdomain to which it sends the requests:

//  Pre-process the nock definitions as scope filtering has to be defined before the nocks are defined (due to its very hacky nature).constnockDefs=nock.loadDefs(pathToJson)nockDefs.forEach(def=>{//  Do something with the definition object e.g. scope filtering.def.options={    ...def.options,filteringScope:scope=>/^https:\/\/api[0-9]*.dropbox.com/.test(scope),}})//  Load the nocks from pre-processed definitions.constnocks=nock.define(nockDefs)

Recording request headers by default is deemed more trouble than it's worth as some of them depend on the timestamp or other values that may change after the tests have been recorded thus leading to complex postprocessing of recorded tests. Thus by default the request headers are not recorded.

The genuine use cases for recording request headers (e.g. checking authorization) can be handled manually or by usingenable_reqheaders_recording inrecorder.rec() options.

nock.recorder.rec({dont_print:true,output_objects:true,enable_reqheaders_recording:true,})

Note that even when request headers recording is enabled Nock will never recorduser-agent headers.user-agent values change with the version of Node and underlying operating system and are thus useless for matching as all that they can indicate is that the user agent isn't the one that was used to record the tests.

Nock will print usingconsole.log by default (assuming thatdont_print isfalse). If a different function is passed intologging, nock will send the log string (or object, when usingoutput_objects) to that function. Here's a basic example.

constappendLogToFile=content=>{fs.appendFile('record.txt',content)}nock.recorder.rec({logging:appendLogToFile,})

By default, nock will wrap its output with the separator string<<<<<<-- cut here -->>>>>> before and after anything it prints, whether to the console or a custom log function given with thelogging option.

To disable this, setuse_separator to false.

nock.recorder.rec({use_separator:false,})

This allows removing a specific interceptor. This can be either an interceptor instance or options for a url. It's useful when there's a list of common interceptors shared between tests, where an individual test requires one of the shared interceptors to behave differently.

Examples:

nock.removeInterceptor({hostname:'localhost',path:'/mockedResource',// method defaults to `GET`// proto defaullts to `http`})

nock.removeInterceptor({hostname:'localhost',path:'/login',method:'POST',proto:'https',})

constinterceptor=nock('http://example.org').get('somePath')nock.removeInterceptor(interceptor)

Note.reply(...) method returns Scope, not Interceptor, and so it is not a valid argument fornock.removeInterceptor. So if your method chain ends with.reply to be used withnock.removeInterceptor the chain need to be break in between:

// this will NOT workconstinterceptor=nock('http://example.org').get('somePath').reply(200,'OK')nock.removeInterceptor(interceptor)// this is how it should beconstinterceptor=nock('http://example.org').get('somePath')interceptor.reply(200,'OK')nock.removeInterceptor(interceptor)

A scope emits the following events:

• emit('request', function(req, interceptor, body))
• emit('replied', function(req, interceptor))

You can also listen for no match events like this:

nock.emitter.on('no match',req=>{})

Fixture recording support and playback.

You must specify a fixture directory before using, for example:

In your test helper

constnockBack=require('nock').backnockBack.fixtures='/path/to/fixtures/'nockBack.setMode('record')

• nockBack.fixtures : path to fixture directory
• nockBack.setMode() : the mode to use

By default if the fixture doesn't exist, anockBack will create a new fixture and save the recorded outputfor you. The next time you run the test, if the fixture exists, it will be loaded in.

Thethis context of the callback function will have a propertyscopes to access all of the loadednock scopes.

constnockBack=require('nock').backconstrequest=require('request')nockBack.setMode('record')nockBack.fixtures=__dirname+'/nockFixtures'//this only needs to be set once in your test helper// recording of the fixturenockBack('zomboFixture.json',nockDone=>{request.get('http://zombo.com',(err,res,body)=>{nockDone()// usage of the created fixturenockBack('zomboFixture.json',function(nockDone){http.get('http://zombo.com/').end()// respond body "Ok"this.assertScopesFinished()//throws an exception if all nocks in fixture were not satisfiedhttp.get('http://zombo.com/').end()// throws exception because someFixture.json only had one callnockDone()//never gets here})})})

If your tests are using promises then usenockBack like this:

returnnockBack('promisedFixture.json').then(({ nockDone, context})=>{//  do your tests returning a promise and chain it with//  `.then(nockDone)`})

Or, with async/await:

const{ nockDone, context}=awaitnockBack('promisedFixture.json')//  your test codenockDone()

As an optional second parameter you can pass the following options

• before: a preprocessing function, gets called before nock.define
• after: a postprocessing function, gets called after nock.define
• afterRecord: a postprocessing function, gets called after recording. Is passed the array of scopes recorded and should return the intact array, a modified version of the array, or if custom formatting is desired, a stringified version of the array to save to the fixture
• recorder: custom options to pass to the recorder

functionprepareScope(scope){scope.filteringRequestBody=(body,aRecordedBody)=>{if(typeofbody!=='string'||typeofaRecordedBody!=='string'){returnbody}constrecordedBodyResult=/timestamp:([0-9]+)/.exec(aRecordedBody)if(recordedBodyResult){constrecordedTimestamp=recordedBodyResult[1]returnbody.replace(/(timestamp):([0-9]+)/g,(match,key,value)=>`${key}:${recordedTimestamp}`,)}else{returnbody}}}nockBack('exampleFixture.json',{before:prepareScope},nockDone=>{request.get('http://example.com',function(err,res,body){// do your testsnockDone()})})

To set the mode callnockBack.setMode(mode) or run the tests with theNOCK_BACK_MODE environment variable set before loading nock. If the mode needs to be changed programmatically, the following is valid:nockBack.setMode(nockBack.currentMode)

• wild: all requests go out to the internet, don't replay anything, doesn't record anything

• dryrun: The default, use recorded nocks, allow http calls, doesn't record anything, useful for writing new tests

• record: use recorded nocks, record new nocks

• update: remove recorded nocks, record nocks

• lockdown: use recorded nocks, disables all http calls even when not nocked, doesn't record

Although you can certainly open the recorded JSON fixtures to manually verify requests recorded by nockBack - it's sometimes useful to put those expectations in your tests.

Thecontext.query function can be used to return all of the interceptors that were recored in a given fixture.

By itself, this functions as a negative expectation - you can verify that certain calls do NOT happen in the fixture. SinceassertScopesFinished can verify there are noextra calls in a fixture - pairing the two methods allows you to verify the exact set of HTTP interactions recorded in the fixture. This is especially useful when re-recording for instance, a service that synchronizes via several HTTP calls to an external API.

NB: The list of fixtures is only available when reading. It will only be populated for nocks that are played back from fixtures.

it('#synchronize - synchronize with the external API',asynclocalState=>{const{ nockDone, context}=awaitback('http-interaction.json')constsyncronizer=newSynchronizer(localState)sycnronizer.syncronize()nockDone()context.assertScopesFinished()expect(context.query()).toEqual(expect.arrayContaining([expect.objectContaining({method:'POST',path:'/create/thing',}),expect.objectContaining({method:'POST',path:'create/thing',}),]),)})

"No match for response" when using got with error responses

Got automatically retries failed requests twice. That means if you have atest which mocks a 4xx or 5xx response, got will immediately reissue it. Atthat point, the mock will have been consumed and the second request will errorout withNock: No match for request.

The same is true for.replyWithError().

Adding{ retry: 0 } to thegot invocations will disable retrying, e.g.:

awaitgot('http://example.test/',{retry:0})

If you need to do this in all your tests, you can create a modulegot_client.js which exports a custom got instance:

constgot=require('got')module.exports=got.extend({retry:0})

This is how it's handled in Nock itself (see#1523).

When an ES module importsrequest with a namespaced import likeimport * as http from "node:http", and the module is imported beforenock, requests madeby this module are not intercepted. You can fix this by telling Node to preloadnock using the--import=nockCLI optionor setting theNODE_OPTIONS=--import=nock environment variable.

To use Nock withAxios, you may need to configure Axios to use the Nodeadapter as in the example below:

importaxiosfrom'axios'importnockfrom'nock'importtestfrom'ava'// You can use any test framework.// If you are using jsdom, axios will default to using the XHR adapter which// can't be intercepted by nock. So, configure axios to use the node adapter.//// References:// https://github.com/axios/axios/pull/5277axios.defaults.adapter='http'test('can fetch test response',asynct=>{// Set up the mock request.constscope=nock('http://localhost').get('/test').reply(200,'test response')// Make the request. Note that the hostname must match exactly what is passed// to `nock()`. Alternatively you can set `axios.defaults.host = 'http://localhost'`// and run `axios.get('/test')`.awaitaxios.get('http://localhost/test')// Assert that the expected request was made.scope.done()})

For Nock + Axios + Jest to work, you'll have to also adapt your jest.config.js, like so:

constconfig={moduleNameMapper:{// Force CommonJS build for http adapter to be available.// via https://github.com/axios/axios/issues/5101#issuecomment-1276572468'^axios$':require.resolve('axios'),},}

Memory issues can be avoided by callingnock.restore() after each test suite.
One of the core principles ofJest is that it runs tests in isolation.It does this by manipulating the modules cache of Node in a way that conflicts with how Nock monkey patches the builtinhttp andhttps modules.Related issue with more details.

Nock uses node internalsdebuglog, so just run with environmental variableNODE_DEBUG set tonock:*.

user@local$NODE_DEBUG=nock:* node my_test.js

Each step in the matching process is logged this way and can be useful when determining why a request was not intercepted by Nock.

For example the following shows that matching failed because the request had an extra search parameter.

nock('http://example.com').get('/').query({foo:'bar'}).reply()awaitgot('http://example.com/?foo=bar&baz=foz')

user@local$DEBUG=nock:scope:example.com node my_test.js...NOCK:SCOPE:EXAMPLE.COM 103514: Interceptor queries: {"foo":"bar"}NOCK:SCOPE:EXAMPLE.COM 103514:     Request queries: {"foo":"bar","baz":"foz"}NOCK:SCOPE:EXAMPLE.COM 103514: query matching failed

Thanks for wanting to contribute! Take a look at ourContributing Guide for notes on our commit message conventions and how to run tests.

Please note that this project is released with aContributor Code of Conduct.By participating in this project you agree to abide by its terms.

Thanks goes to these wonderful people (emoji key):

Pedro Teixeira 💻🚧	n30n0v 💻	Richard Littauer 🚧💻📝	Ian Walker-Sperber 💻	Ivan Erceg 💻🚧	Paul Melnikow 💻🚧	Gregor Martynus 💻🚧💼💵📝
Hutson Betts 💵	Jonas Lilja 💵💻	Benjamin Ki 💵	Chad Fawcett 💵	Laurence Dougal Myers 💻	Sébastien Van Bruaene 💻⚠️	Aras Abbasi 💻⚠️🚧
Saryev Rustam 💻⚠️	Michael Solomon 🚧💻📖

This project follows theall-contributors specification. Contributions of any kind welcome!

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Copyright (c) 2011–2019Pedro Teixeira and othercontributors.