Supertest Capture Error Plugin

This plugin allows you to capture and modify an assertion error that occured in a test.

Typical use case is to provide more debugging information when your assertion has failed.

Installation

npm i -D supertest-capture-error

Example Usage

Let's use the plugin to add request url and response body information to error messages:

const supertest = require('supertest');
const use = require('superagent-use'); // so that we can apply capturing for each request
const captureError = require('supertest-capture-error');

// apply capturing for each request
const request = use(supertest('http://localhost'))
  .use(captureError((error, test) => {
    // modify error message to suit our needs:
    error.message += ` at ${test.url}\n` +
      `Response Body:\n${test.res.text}`;
    error.stack = ''; // this is useless anyway
  }));

Now, let's say that we're using Mocha and testing user creation endpoint. Our server expects user name and password, and will respond with a validation error if something went wrong. Here's how we'd use request:

request
  .post('/users')
  .send({name: 'john'})
  .expect(201)
  .end(done);

Results

default Supertest, without the plugin:

Error: expected 201 "Created", got 422 "Unprocessable Entity"
at Test._assertStatus (node_modules/supertest/lib/test.js:268:12)
at Test._assertFunction (node_modules/supertest/lib/test.js:283:11)
at Test.assert (node_modules/supertest/lib/test.js:173:18)
at assert (node_modules/supertest/lib/test.js:131:12)
at node_modules/supertest/lib/test.js:128:5
at Test.Request.callback (node_modules/superagent/lib/node/index.js:706:12)
at IncomingMessage.parser (node_modules/superagent/lib/node/index.js:906:18)
at endReadableNT (_stream_readable.js:1064:12)
at _combinedTickCallback (internal/process/next_tick.js:138:11)
at process._tickCallback (internal/process/next_tick.js:180:9)

with the plugin setup as above:

Error: expected 201 "Created", got 422 "Unprocessable Entity" at http://localhost/users
Response Body:
You need to pass the "password" field as well

Possibilities

test object that gets passed into the plugin is quite huge and contains full request, response and some additional Supertest data. I encourage you to inspect its properties. You can use all of that to enhance your debugging experience.