Scrubbers.md

Scrubbers

Contents

• Interface
• Configuring Scrubbers
• Guid Scrubbing
• RegEx Scrubbing
• Date Scrubbing
  • How to do it
  • Supported formats
• Scrubbing multiple parts of a string
• Using templates

If you are having trouble getting tests running reproducibly, you might need to use a “scrubber” to convert the non-deterministic text to something stable.

Interface

Fundamentally, a scrubber is function that takes a string and returns a string. You can create ones by passing in a function or a lambda. We also have some pre-made ones for your convenience.

Configuring Scrubbers

You can configure all of the Approvals.verify methods to use scrubbers via the Options parameter.

For example:

Approvals.verifyAll("guids", guids, new Options(Scrubbers::scrubGuid));

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Guid Scrubbing

Let's say you have the following Guids in your output:

String[] guids = {"2fd78d4a-ad49-447d-96a8-deda585a9aa5",
                  "2fd78d4a-1111-1111-1111-deda585a9aa5",
                  "2fd78d4a-3333-3333-3333-deda585a9aa5",
                  "2fd78d4a-ad49-447d-96a8-deda585a9aa5",
                  "2fd78d4a-ad49-447d-96a8-deda585a9aa5 and text"};

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You can make this output deterministic by using a scrubber in the options. For example:

Approvals.verifyAll("guids", guids, new Options(Scrubbers::scrubGuid));

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This will result in the following .approved.txt file

guids[0] = guid_1
guids[1] = guid_2
guids[2] = guid_3
guids[3] = guid_1
guids[4] = guid_1 and text

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Note: If a Guid is used in multiple places, it will be scrubbed using the same replacement. That is why you see guid_1 three times.

RegEx Scrubbing

Using a regex search term

For example, here is an example where random numbers are scrubbed:

String input = "Hello " + new Random().nextInt(100) + " World!";
Approvals.verify(input, new Options(new RegExScrubber("(\\d+)", "[number]")));

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producing

Hello [number] World!

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Date Scrubbing

How to do it

The easiest way to scrub a date is by calling

Approvals.verify("created at 03:14:15", new Options().withScrubber(DateScrubber.getScrubberFor("00:00:00")));

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which will produce

created at [Date1]

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Supported formats

Example Date	RegEx Pattern
Tue May 13 16:30:00	[a-zA-Z]{3} [a-zA-Z]{3} \d{2} \d{2}:\d{2}:\d{2}
Wed Nov 17 22:28:33 EET 2021	[a-zA-Z]{3} [a-zA-Z]{3} \d{2} \d{2}:\d{2}:\d{2} [a-zA-Z]{3,4} \d{4}
Wed, 21 Oct 2015 07:28:00 GMT	(Mon|Tue|Wed|Thu|Fri|Sat|Sun), \d{2} (Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \d{4} \d{2}:\d{2}:\d{2} GMT
Tue May 13 2014 23:30:00.789	[a-zA-Z]{3} [a-zA-Z]{3} \d{2} \d{4} \d{2}:\d{2}:\d{2}.\d{3}
Tue May 13 16:30:00 -0800 2014	[a-zA-Z]{3} [a-zA-Z]{3} \d{2} \d{2}:\d{2}:\d{2} -\d{4} \d{4}
13 May 2014 23:50:49,999	\d{2} [a-zA-Z]{3} \d{4} \d{2}:\d{2}:\d{2},\d{3}
Oct 13 15:29	[A-Za-z]{3} \d{2} \d{2}:\d{2}
May 13, 2014 11:30:00 PM PST	[a-zA-Z]{3} \d{2}, \d{4} \d{2}:\d{2}:\d{2} [a-zA-Z]{2} [a-zA-Z]{3}
23:30:00	\d{2}:\d{2}:\d{2}
2014/05/13 16:30:59.786	\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2}(.\d{3})?
2020-9-10T08:07Z	\d{4}-\d{1,2}-\d{1,2}T\d{1,2}:\d{2}Z
2020-09-10T08:07:89Z	\d{4}-\d{1,2}-\d{1,2}T\d{1,2}:\d{2}:\d{2}Z
2020-09-10T01:23:45.678Z	\d{4}-\d{1,2}-\d{1,2}T\d{1,2}:\d{2}:\d{2}.\d{3}Z
20210505T091112Z	\d{8}T\d{6}Z
2024-12-17	\d{4}-\d{2}-\d{2}
2024-12-18T14:04:46.746130Z	\d{4}-\d{1,2}-\d{1,2}T\d{1,2}:\d{2}:\d{2}(.\d{1,9})?Z
13/05/2014 23:50:49	\d{2}[-/.]\d{2}[-/.]\d{4}\s\d{2}:\d{2}(:\d{2})?( (?:pm|am|PM|AM))?

Scrubbing multiple parts of a string

If you need to do scrubbing of multiple things, the easiest way is to create multiple scrubbers and then combine them.

final Scrubber portScrubber = new RegExScrubber(":\\d+/", ":[port]/");
final Scrubber dateScrubber = DateScrubber.getScrubberFor("20210505T091112Z");
final Scrubber signatureScrubber = new RegExScrubber("Signature=.+", "Signature=[signature]");
Scrubber scrubber = Scrubbers.scrubAll(portScrubber, dateScrubber, signatureScrubber);
Approvals.verify("http://127.0.0.1:55079/foo/bar?Date=20210505T091112Z&Signature=4a7dd6f09c1e",
    new Options(scrubber));

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will result in

http://127.0.0.1:[port]/foo/bar?Date=[Date1]&Signature=[signature]

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Using templates

Scrubbers.Templates contains many templates that can be inlined.

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