Record, mock, and proxy HTTP traffic using the connect-prism middleware.
This plugin requires Grunt ~0.4.1 and the grunt-contrib-connect ~0.7.1 plugin to already be installed.
If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:
npm install grunt-connect-prism --save-devOne the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:
grunt.loadNpmTasks('grunt-connect-prism');This grunt plugin is a wrapper around the connect-prism middleware.
Prism is similar to the Ruby project VCR.
The purpose of this plugin is to provide an easy way for front end developers to record HTTP responses returned by their API (or some other remote source) and then be able replay the responses in the future. It's basically an HTTP cache, but for developers working on a Single Page Application (SPA).
It's useful for mocking complex & high latency API calls during development. It's also useful when writing e2e tests for your SPA only, removing the server from the equation. This results in much faster execution of your e2e test suite.
Prism works by adding a custom connect middleware to the connect server provided by the grunt-contrib-connect plugin.
There are currently 4 supported modes of operation.
The record mode will allow you to both record and proxy all HTTP traffic for a certain endpoint on your connect development server. For example, if in production your API sits at an endpoint /api then you may be currently proxying requests to a server you're hosting locally on another port or to an integration machine somewhere else. You may have also attempted to mock out services that make HTTP calls in your client side code itself. While in record mode you can navigate your application and trigger all the types of API calls you would like to have recorded. Prism will then listen for responses and serialize them to disk. When you want to read these responses instead of proxying traffic to the real server you shutdown and switch to the 'mock' mode.
To make mocks more readable, responses with a content-type of json or javascript will have their data stringified as an object. If the content-type is anything other than json or if stringification fails then it falls back to a string.
If the server returns a compressed response (gzip or deflate are supported), then prism will decompress the payload when recording the response.
Example mock generated:
{
"requestUrl": "/api/ponies",
"contentType": "application/json",
"statusCode": 200,
"data": {
"text": "my little ponies"
}
}The mock (read) mode will listen for requests to a certain endpoint. When a request matches an endpoint it will attempt to find a previously recorded response in the directory you defined mocks to be saved in (./mocks by default).
If a matching response is not found then prism will return a 404. Prism will also create a mock during a 404. This is useful when you want to mock API endpoints that may not exist yet. To avoid having the subsequent request from returning the generated empty mock, the file has a .404 extension. To use the mock, populate it with the appropriate values and remove the .404 extension. This feature was contributed by Miloš Mošovský.
As its name implies this operation will mock and record. This mode will first attempt to load a mock if one exists. If a mock does not exist it will then proxy the request and record the response instead of returning a 404.
And finally, prism supports simple proxying in much the same way as the grunt-connect-proxy plugin works. In fact, this plugin is heavily inspired by that project. While in proxy mode, listening events for recording and mocking are disabled.
This configuration is based on a modification to the connect middleware configuration that the yeoman angular-generator will create.
connect: {
livereload: {
options: {
middleware: function(connect) {
return [
require('grunt-connect-prism/middleware'),
connect.static('.tmp'),
connect().use(
'/bower_components',
connect.static('./bower_components')
),
connect.static(appConfig.app)
];
}
}
}
}In your project's Gruntfile, add a section named prism.
You can add all the options in the root task options, in a target options, or a mix of both (where the target options will inherit from the root options). If only the root prism options are provided than a prism instance with the name 'default' will be created.
prism: {
options: {
mocksPath: './mocks',
host: 'localhost',
port: 8090,
https: false,
changeOrigin: true
},
server: {
options: {
mode: 'record',
context: '/api'
}
}
}Typically you will want to run your prism task while you're running your development server, or while e2e tests are running. There are several different ways to add prism tasks to the grunt task queue.
Usage)
'prism[:target[:mode]]'
If 'prism' is executed by itself then all prism targets will be created.
If a target is supplied (i.e. 'prism:targetOne') then only that prism target instance will be created.
If a target and mode are supplied (i.e. 'prism:targetOne:record') then only that prism target instance will be created and will be in the record mode.
Basic grunt serve example.
grunt.registerTask('serve', function () {
grunt.task.run([
'clean:server',
'compass:server',
'prism',
'livereload-start',
'connect:livereload',
'open',
'watch'
]);
});Target and mode override example (i.e. grunt serve:targetOne:record).
grunt.registerTask('serve', function (target, prismMode) {
grunt.task.run([
'clean:server',
'compass:server',
'prism:' + target + ':' + prismMode, /* see mode configuration for more details */
'livereload-start',
'connect:livereload',
'open',
'watch'
]);
});Type: String
Default: 'proxy'
Values: 'record' | 'mock' | 'proxy' | 'mockrecord'
By setting a mode you create an explicit declaration that the context you're proxying will always be in the configured mode. You can optionally override the mode of all the proxies for a target by passing in a 3rd parameter to the prism grunt task prism:[target]:[mode]
i.e. grunt prism:server:mock
Type: String
Default: './mocks'
Path to the root directory you want to record and mock responses. If the directory does not exist then prism will attempt to create it. If prism is executed with a target then recorded and mocked responses will be read from './mocks/targetName'. If no target is defined then only the default prism options will be used.
Type: String
Default: n/a
The starting context of your API that you are proxying. This should be from the root of your webserver. All requests that start with this context string will be used.
Type: String
Default: n/a
The server name or IP of the API that you are proxying.
Type: Integer
Default: n/a
The port number of the API that you are proxying.
Type: Boolean
Default: false
The http scheme of the API you are proxying. true === https, false === http
Type: Boolean
Default: false
Whether to change the origin on the request to the proxy, or keep the original origin.
Type: String or Integer
Default: 0
Values: A number in milliseconds | 'auto' | 'fast' | 'slow'
Delay will work with all modes.
This option allows you to simulate a delay when returning a mock response to the user. Sometimes it's handy to simulate a delay because this will give you a better impression of how the user experience of your app will be when fully integrated with a backend server.
You can configure an exact delay in milliseconds or one of the precreated options which returns a random delay in a certain range.
- auto: 500 to 1750 ms
- fast: 150 to 1000 ms
- slow: 1500 to 3000 ms
Thanks again to Miloš Mošovský for this feature.
Type: Object
Default: {}
Add rewrite rules that prism will apply to all requests. This functionality was copied from grunt-connect-proxy and works the exact same way. You can configure a list of rewrite rules with an object.
{
'^/removingcontext': '',
'^/changingcontext': '/anothercontext'
}Type: Boolean
Default: false
Use the request body in conjunction with the request URL in order to generate a unique hash for the serialized response. This is useful when you want to record responses for requests with distinct request bodies.
i.e.) Require two different responses for a POST a request with a payload in the request body.
Thanks to Matt Philips for requesting and helping get this feature implemented.
Type: Function | String
Default: 'default'
Use one of the builtin or your own strategy to generate and read mock response filenames.
Builtin generators:
'default'
Generates filenames strictly based on request URL and request body (when hashFullRequest is configured). Generates a SHA1 hash.
i.e.)
04d5d366d8e8dbea60bb9187f7610423a527ca24.json
'humanReadable'
Generates a somewhat readable filename based on the request URL. The request URL will replace characters / ? < > \ : * | " \. A hash from the 'default' generator is appended to the end of the scrubbed request URL. The filename is truncated to 255 characters for maximum compatibility across filesystems.
i.e.)
_is_this_url_really=that&readable=at&all_09b2ed55fb2b388fbe02c69e94bca5d86ff7247c.json
This function accepts a function that takes 2 parameters:
- The prism config associated with this request context.
- The request object.
i.e.) Generate a filename based on the SHA1 hash of the request URL.
function(config, req) {
var crypto = require('crypto');
var path = require('path');
var shasum = crypto.createHash('sha1');
shasum.update(req.url);
return shasum.digest('hex');
}Type: Boolean or [] of String or Regular expression
Default: false
This will filter parameters out of both the saved requestUrl and the hash used in the default file generation algorithm. This allows users to replay requests which use for example today's date or a random number as query parameters.
- 0.7.6 Use connect-prism 0.7.5 to fix socket hang up issue by handling aborted requests appropriately (issue #15). Issue #527 from node-http-proxy project.
- 0.7.4 Support 'default' instance. Re-factor tests.
- 0.7.3 Upgrade to connect-prism 0.7.3.
- 0.7.1 Upgrade to connect-prism 0.7.1.
- 0.7.0 Upgrade to connect-prism 0.7.0.
Fix legacy middleware call. - 0.6.0 Upgrade to connect-prism 0.6.0.
Fix spec to use PrismManager. - 0.5.0 Upgrade to connect-prism 0.5.0.
- 0.4.2 Upgrade to connect-prism 0.4.2.
- 0.4.1 Upgrade to connect-prism 0.4.1.
- 0.3.0 Use connect-prism core library.
- 0.2.2 Support change origin.
- 0.2.1 Fixed record mode and tests so we don't release broken again!
- 0.2.0 Support 'cassettes' by putting mocks into directories named after target.
Use http-proxy 0.10.4 to workaround around socket hangup issues in 1.1.4. - 0.1.1 Stop recording all response headers.
Only capture content-type. - 0.1.0 Initial release
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