/approval-tests

Node.js Scrubbers

Scrubbers normalize dynamic data before comparison. Flaky tests across environments usually means unscrubbed timestamps, UUIDs, ports, or paths.

Imports

const { Scrubbers } = require('approvals').scrubbers;
// Or:
import { Scrubbers } from 'approvals/lib/Scrubbers/Scrubbers';

Built-in Scrubbers

guidScrubber

Replaces UUIDs with guid_1, guid_2, etc.

const scrubber = Scrubbers.createGuidScrubber();

// Or legacy static method:
Scrubbers.guidScrubber(data);

Example:

import { verifyAsJson } from 'approvals/lib/Providers/Jest/JestApprovals';
import { Options } from 'approvals/lib/Core/Options';
import { Scrubbers } from 'approvals/lib/Scrubbers/Scrubbers';

verifyAsJson(
  { id: '58f471f1-8b1f-413c-8971-21cb23bfc8f2', name: 'Alice' },
  new Options().withScrubber(Scrubbers.createGuidScrubber())
);
// Result: { id: "guid_1", name: "Alice" }

Custom Regex Scrubber

Scrubbers.createReqexScrubber(regex, replacement)

Note: Method name has typo "Reqex" (not "Regex").

With String Replacement

const scrubber = Scrubbers.createReqexScrubber(
  /\d{4}-\d{2}-\d{2}/gi,
  '<DATE>'
);

verify(
  'Created: 2024-01-15',
  new Options().withScrubber(scrubber)
);
// Result: Created: <DATE>

With Lambda Replacement

const scrubber = Scrubbers.createReqexScrubber(
  /user_\d+/gi,
  (index) => `<user_${index}>`
);

verify(
  'user_123 assigned to user_456',
  new Options().withScrubber(scrubber)
);
// Result: <user_0> assigned to <user_1>

Combining Scrubbers

multiScrubber

Chain multiple scrubbers:

const scrubber = Scrubbers.multiScrubber([
  Scrubbers.createGuidScrubber(),
  Scrubbers.createReqexScrubber(/\d{4}-\d{2}-\d{2}/, '<DATE>'),
  (text) => text.replace(/password=\w+/, 'password=<HIDDEN>')
]);

verify(data, new Options().withScrubber(scrubber));

Date Scrubber

import { DateScrubber } from 'approvals/lib/Scrubbers/DateScrubber';

const scrubber = DateScrubber.getScrubberFor('2020-09-10T08:07:89Z');

Supported formats (pass an example to getScrubberFor()):

• 23:30:00 - Time only
• 2020-09-10T08:07Z - ISO 8601 short
• 2020-09-10T08:07:89Z - ISO 8601 with seconds
• 2020-09-10T01:23:45.678Z - ISO 8601 with milliseconds
• 20210505T091112Z - Compact ISO format
• 2014/05/13 16:30:59.786 - Slash-separated with milliseconds
• Tue May 13 16:30:00 - Day Mon DD HH:MM:SS
• Tue May 13 16:30:00 -0800 2014 - With timezone offset
• Wed Nov 17 22:28:33 EET 2021 - With timezone name
• Tue May 13 2014 23:30:00.789 - Day Mon DD YYYY HH:MM:SS.ms
• 13 May 2014 23:50:49,999 - DD Mon YYYY HH:MM:SS,ms
• May 13, 2014 11:30:00 PM PST - Mon DD, YYYY HH:MM:SS AM/PM TZ
• Sun, 06 Nov 2022 11:23:20 GMT - RFC 2822

Using with verify Functions

With Options (Jest)

import { verify } from 'approvals/lib/Providers/Jest/JestApprovals';
import { Options } from 'approvals/lib/Core/Options';

verify(data, new Options().withScrubber(myScrubber));

With verifyAndScrub (legacy)

const approvals = require('approvals');

approvals.verifyAndScrub(
  __dirname,
  'test_name',
  data,
  myScrubber
);

With verifyAsJSONAndScrub

approvals.verifyAsJSONAndScrub(
  __dirname,
  'test_name',
  jsonData,
  myScrubber
);

Custom Scrubber Function

Any function string -> string works:

const myScrubber = (text) => {
  return text
    .replace(/Bearer [a-zA-Z0-9]+/, 'Bearer <TOKEN>')
    .replace(/\d{10}/, '<TIMESTAMP>');
};

verify(apiResponse, new Options().withScrubber(myScrubber));

Common Patterns

Scrub API Response

const apiScrubber = Scrubbers.multiScrubber([
  Scrubbers.createGuidScrubber(),
  DateScrubber.getScrubberFor('2020-09-10T01:23:45.678Z'),
  Scrubbers.createReqexScrubber(/"token":\s*"[^"]+"/, '"token": "<TOKEN>"'),
]);

verifyAsJson(response, new Options().withScrubber(apiScrubber));

Scrub Log Output

const logScrubber = Scrubbers.multiScrubber([
  DateScrubber.getScrubberFor('23:30:00'),
  (text) => text.split('\n')
    .filter(line => !line.includes('DEBUG'))
    .join('\n'),
]);