Mock0 is a zero effort http(s) mocking library with build-in capture to file solution. It can intercept http(s) traffic and capture requests and responses in a JSON formatted file. Once capture is done, it can be used with zero effort to play back responses for the captured requests and use it as mock for unit tests.

The example code below starts capturing requests and responses to a file:

require('mock0').capture('mock-data.json', ['x-amz-target'])

Second parameter of the capture method (in this example ['x-amz-target']) is an array of headers that will be saved. Other headers will be dropped.

That's it. The file saved above will look like this example:

[
  {
    "request": {
      "method": "POST",
      "uri": "https://codecommit.eu-central-1.amazonaws.com/",
      "headers": {
        "x-amz-target": "CodeCommit_20150413.ListRepositories"
      },
      "body": "{}"
    },
    "response": {
      "statusCode": 200,
      "headers": [],
      "body": "{\n  \"repositories\": [\n    {\n      \"repositoryId\": \"882407d2-17b3-4b9d-a420-8bb1f8730822\",\n      \"repositoryName\": \"test1\"\n    }\n  ]\n}"
    }
  }
]

This request was made by aws-sdk node module by the following code:

const AWS = require('aws-sdk')
AWS.config.region = 'eu-central-1'
AWS.config.credentials = new AWS.SharedIniFileCredentials({ profile: 'dev' })
const CodeCommit = new AWS.CodeCommit()
CodeCommit.listRepositories({ }, (err, data) => { console.log(err, data) })

The example code below starts playing back the requests and responses from the previously captured file:

require('mock0').mock('mock-data.json')

Now all setup. If you run the code below with fake credentials, it will show the exact result as the one which has proper access, because now the mock0 will replay back the captured response.

const AWS = require('aws-sdk')
AWS.config.region = 'eu-central-1'
AWS.config.credentials = { accessKeyId: 'fake-key', secretAccessKey: 'fake-secret' }
const CodeCommit = new AWS.CodeCommit()
CodeCommit.listRepositories({ }, (err, data) => { console.log(err, data) })

npm install --save mock0

Versioning of this module follows the Schemantic Versioning standard. The current version depend on the following two external modules: axios and mitm. This might change in the future.

If you find an issues or you have a feature request, please feel free to contact me directly Ivan Marinov, or create an issue in the issue tracker.