mockserver

mockserver

mockserver is a library that will help you mocking your APIs in a matter of seconds: you simply organize your mocked HTTP responses in a bunch of mock files and it will serve them like they were coming from a real API; in this way you can write your frontends without caring too much whether your backend is really ready or not.

Installation

Mockserver can be installed globally if you need to run it as a command:

$ npm install -g mockserver

$ mockserver -p 8080 -m test/mocks
Mockserver serving mocks under "test/mocks" at http://localhost:8080

or as a regular NPM module if you need to use it as a library within your code:

npm install mockserver

then in your test file:

var http    =  require('http');
var mockserver  =  require('mockserver');

http.createServer(mockserver('path/to/your/mocks')).listen(9001);

This will run a simple HTTP webserver, handled by mockserver, on port 9001.

At this point you can simply define your first mock: create a file in path/to/your/mocks/example-response called GET.mock:

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8

{
   "Random": "content"
}

If you open your browser at http://localhost:9001/example-response you will see something like this:

And it's over: now you can start writing your frontends without having to wait for your APIs to be ready, or without having to spend too much time mocking them, as mockserver lets you do it in seconds.

Mock files

As you probably understood, mock files' naming conventions are based on the response that they are going to serve:

$REQUEST-PATH/$HTTP-METHOD.mock

For example, let's say that you wanna mock the response of a POST request to /users, you would simply need to create a file named POST.mock under users/.

The content of the mock files needs to be a valid HTTP response, for example:

HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8

{
   "Accept-Language": "en-US,en;q=0.8",
   "Host": "headers.jsontest.com",
   "Accept-Charset": "ISO-8859-1,utf-8;q=0.7,*;q=0.3",
   "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
}

Check our own mocks as a reference.

Custom Headers

You can specify request headers to include, which allows you to change the response based on what headers are provided. To do this, you need to let mockserver know which headers matter, by setting the headers array on the mockserver object, like so:

var mockserver = require('mockserver');
mockserver.headers = ['Authorization', 'X-My-Header'];

Any headers that are set and occur within the array will now be appended to the filename, immediately after the HTTP method, like so:

GET /hello
Authorization: 12345

hello/GET_Authorization=12345.mock

GET /hello
X-My-Header: cow
Authorization: 12345

hello/GET_Authorization=12345_X-My-Header=cow.mock

Note: The order of the headers within the headers array determines the order of the values within the filename.

The server will always attempt to match the file with the most tracked headers, then it will try permutations of headers until it finds one that matches. This means that, in the previous example, the server will look for files in this order:

hello/GET_Authorization=12345_X-My-Header=cow.mock
hello/GET_X-My-Header_Authorization=12345=cow.mock
hello/GET_Authorization=12345.mock
hello/GET_X-My-Header=cow.mock
hello/GET.mock

The first one matched is the one returned, favoring more matches and headers earlier in the array.

The headers array can be set or modified at any time.

Query string parameters and POST body

In order to support query string parameters in the mocked files, replace all occurrences of ? with --, then append the entire string to the end of the file.

GET /hello?a=b

hello/GET--a=b.mock

GET /test?a=b&c=d?

test/GET--a=b&c=d--.mock

(This has been introduced to overcome issues in file naming on windows)

To combine custom headers and query parameters, simply add the headers then add the parameters:

GET /hello?a=b
Authorization: 12345

hello/GET_Authorization=12345--a=b.mock

Similarly, you can do the same thing with the body of a POST request: if you send Hello=World as body of the request, mockserver will look for a file called POST--Hello=World.mock

In the same way, if your POST body is a json like {"json": "yesPlease"}, mockserver will look for a file called POST--{"json": "yesPlease"}.mock

If no parametrized mock file is found, mockserver will default to the nearest headers based .mock file

ex:

GET /hello?a=b
Authorization: 12345

if there's no hello/GET_Authorization=12345--a=b.mock, we'll default to hello/GET_Authorization=12345.mock or to hello/GET.mock

Tests

Tests run on travis, but if you wanna run them locally you simply have to run mocha or its verbose cousin ./node_modules/mocha/bin/mocha (if you don't have mocha installed globally).