jest-serializer-babel-ast

0.0.5 verified Sat Apr 25 auth: no javascript maintenance

A Jest snapshot serializer that pretty-prints Babel AST nodes (e.g., from @babel/parser) in a human-readable, indented format. Current stable version is 0.0.5 (unreleased beyond). No active release cadence; maintained sporadically. Differentiators: provides a clean, nested view of AST node properties, ideal for snapshot testing Babel plugins or AST transformations. Compared to alternatives like jest-serialize, it is purpose-built for Babel AST and outputs structured property lists. Works with Jest snapshotSerializers configuration.

Common errors

error Cannot find module 'jest-serializer-babel-ast' ↓

cause Package not installed or not present in node_modules.

fix

Run: npm install jest-serializer-babel-ast --save-dev

error TypeError: serializer.serialize is not a function ↓

cause Importing the package incorrectly, e.g., using import default or expecting named exports.

fix

Use: const serializer = require('jest-serializer-babel-ast');

Warnings

gotcha Works only with Babel AST nodes from @babel/parser (babylon). May not handle other parsers or custom AST types. ↓

fix Ensure you are using @babel/parser (or babylon) to generate AST nodes.

gotcha The serializer expects nodes with a 'type' property; non-AST objects will not be serialized by this serializer. ↓

fix Make sure the snapshot content contains Babel AST nodes. For other objects, Jest's default serializer will be used.

deprecated The package is no longer actively maintained. There are no security issues reported, but bugs may remain unaddressed. ↓

fix Consider alternatives like jest-serializer-ast or writing your own serializer with a library like pretty-format.

gotcha Serializer may not show private properties (prefixed with underscore) or Babel node internal metadata (e.g., start/end locations) unless they are enumerable. ↓

fix If you need location data, configure Babel parser to include 'ranges' or check the node's 'loc' property.

Install

npm install jest-serializer-babel-ast

yarn add jest-serializer-babel-ast

pnpm add jest-serializer-babel-ast

Imports

jest-serializer-babel-ast

wrong

import serializer from 'jest-serializer-babel-ast'

correct

Add to jest.snapshotSerializers in package.json or jest.config.js: 'jest-serializer-babel-ast'

This is a Jest serializer, not a module you import directly. It is loaded automatically via Jest configuration.

expect.addSnapshotSerializer
wrong
```
const serializer = require('jest-serializer-babel-ast').default
```
correct
```
expect.addSnapshotSerializer(require('jest-serializer-babel-ast'))
```
If using programmatic registration with expect.addSnapshotSerializer, use require() directly; the package does not export a default.
default (CommonJS)
wrong
```
const { serialize } = require('jest-serializer-babel-ast')
```
correct
```
const serializer = require('jest-serializer-babel-ast')
```
The package exports the serializer object directly (with serialize and test methods), not named exports.

Quickstart

Configures Jest to use the serializer, then generates a human-readable AST snapshot from parsed code.

// jest.config.js or package.json
module.exports = {
  snapshotSerializers: ['jest-serializer-babel-ast']
}

// test file
const { parse } = require('@babel/parser');

test('AST snapshot', () => {
  const ast = parse('const x = 1;', { sourceType: 'module' });
  expect(ast).toMatchSnapshot();
});

// Snapshot output will show structured AST instead of JSON.