npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

dynamic-serializer

v0.2.1

Published

crawls a JSON tree replacing dynamic values with a deterministic integer

Downloads

119

Readme

dynamic-serializer

A class to help you snapshot json trees that contain dynamic values like UIDs

Installation

yarn add dynamic-serializer

What's it do

Jest snapshot testing is great, but it doesn't work if one of your values is non-deterministic. With this package, you can replace those values with deterministic ones.

How's it different from using Jest's built-in snapshotSerializers?

Jests' built-in snapshotSerializers config stops short of being useful (for this case). You can't tell it which fields you'd like to replace. Even if you could, it doesn't hold state to ensure that the same dynamic value turns into the same static value.

Usage

Call it on your JSON tree before taking a snapshot

Example:

// in foo.test.js
import DynamicSerializer from 'dynamic-serializer';

const fullPaths = ['primaryKey', 'wholeArray', 'singleValue.levelOne.arr.3'];

test('makes simple dynamic fields deterministic', () => {
  const dynamicSerializer = new DynamicSerializer();
  const userId = Math.random();
  const results = {
    staticProp: 'Hi there',
    primaryKey: userId,
    wholeArray: [Math.random(), Math.random()],
    singleValue: {
      levelOne: {
        arr: ['badger', 'badger', 'mushroom', 'snake' + Math.random()]
      }
    }
  };
  const moreResults = {
    foreignKey: userId
  };
  dynamicSerializer.toStatic(results, fullPaths);
  dynamicSerializer.toStatic(moreResults, ['foreignKey']);
 
  expect(results).toMatchSnapshot();
  expect(moreResults).toMatchSnapshot();
  expect(results.primaryKey).toBe(moreResults.foreignKey);
});

API

const dynamicSerializer = new DynamicSerializer();

Creates a new instance suitable for a single test.

Methods

dynamicSerializer.toStatic(snapshot, fullPaths)

Options:

  • snapshot: the JSON tree you wish to mutate
  • fullPaths: an array of dot-separated paths. If the final destination of the path is an array, all values will be replaced. If you only want to replace one part of an array, it needs to end in a number. If the JSON structure is an array, start it off with a number, too. For more use cases, see the tests.
  • options: an object with the following:
    • constant: default to false. if true, everything will serialize to the same value. Useful if you're trying to sort objects but every key is serialized so there's no good sort key.

FAQ

Q: Why do you mutate my JSON tree? I heard good functional programming never mutates...

A: Speed, space, and forcing good habits. Mutating is faster and causes less GC. It also forces you to call it just before your snapshot. If you want to do something fancy with the original after calling this, you're doing it wrong.

License

MIT