Nock
Nock is an HTTP 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.
Install
$ npm install nock
Use
On your test, you can setup your mocking object like this:
var nock = require('nock');
var couchdb = nock('http://myapp.iriscouch.com')
.get('/users/1')
.reply(200, {_id: "123ABC", _rev: "946B7D1C", username: 'pgte', email: 'pedro.teixeira@gmail.com'});
This setup says that we will intercept every HTTP call to http://myapp.iriscouch.com
.
It will intercept an HTTP GET request to '/users/1' and reply with a status 200, and the body will contain a user representation in JSON.
Then the test can call the module, and the module will do the HTTP requests.
Specifying request body
You can specify the request body to be matched as the second argument to the get
, post
, put
or delete
specifications like this:
var scope = nock('http://myapp.iriscouch.com')
.post('/users', {username: 'pgte', email: 'pedro.teixeira@gmail.com'})
.reply(201, {ok: true, id: "123ABC", rev: "946B7D1C"});
The request body can be a string or a JSON object.
Specifying replies
You can specify the return status code for a path on the first argument of reply like this:
var scope = nock('http://myapp.iriscouch.com')
.get('/users/1')
.reply(404);
You can also specify the reply body as a string:
var scope = nock('http://www.google.com')
.get('/')
.reply(200, "Hello from Google!");
or as a JSON-encoded object:
var scope = nock('http://myapp.iriscouch.com')
.get('/')
.reply(200, {username: 'pgte', email: 'pedro.teixeira@gmail.com', _id: "4324243fsd"});
or even as a file:
var scope = nock('http://myapp.iriscouch.com')
.get('/')
.replyWithFile(200, __dirname + '/replies/user.json');
You can specify the reply headers like this:
var scope = nock('http://www.headdy.com')
.get('/')
.reply(200, "Hello World!", {'X-My-Headers': 'My Header value'});
HTTP Verbs
Nock supports get, post, put and delete HTTP verbs.
Chaining
You can chain behaviour like this:
var scope = 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'});
Path filtering
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:
var scope = nock('http://api.myservice.com')
.filteringPath(/password=[^&]*/g, 'password=XXX')
.get('/users/1?password=XXX')
.reply(200, 'user');
Or you can use a function:
var scope = nock('http://api.myservice.com')
.filteringPath(function(path) {
return '/ABC';
})
.get('/ABC')
.reply(200, 'user');
Request Body filtering
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 URL.
You can use a regexp for replacement, just like String.prototype.replace:
var scope = 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:
var scope = nock('http://api.myservice.com')
.filteringRequestBody(function(path) {
return 'ABC';
})
.post('/', 'ABC')
.reply(201, 'OK');
Expectations
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 calling scope.done()
. This will assert that all specified calls on that scope were performed.
Example:
var google = nock('http://google.com')
.get('/')
.reply(200, 'Hello from Google!');
// do some stuff
setTimeout(function() {
google.done(); // will throw an assertion error if meanwhile a "GET http://google.com" was not performed.
}, 5000);
.isDone()
You can also call isDone()
, which will return a boolean saying if all the expectations are met or not (instead of throwing an exception);
Logging
Nock can log matches if you pass in a log function like this:
var google = nock('http://google.com')
.log(console.log)
...
How does it work?
Nock works by overriding Node's http.request function.