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extract

extract reads a Jest config object and names the packages it references.

import { extract } from '@repobuddy/jest'
Member Kind
extractPackages() function
toPackageName() function
ExtractedPackage type

buddy check-deps builds on these functions.

extractPackages()

Section titled “extractPackages()”

Lists the packages a Jest config references.

function extractPackages(config: Config): ExtractedPackage[]
Parameter Type Default Effect
config Config from jest required The config object to read.

Returns one entry per package, sorted by name. specifiers and fields in each entry are sorted too.

Fields it reads:

Field How
preset, resolver, runner, testRunner, testSequencer, globalSetup, globalTeardown, snapshotResolver, dependencyExtractor, prettierPath the string value
setupFiles, setupFilesAfterEnv, snapshotSerializers each entry
testEnvironment node becomes jest-environment-node, jsdom becomes jest-environment-jsdom, any other value is read as a specifier
transform each value, or the first item of a [name, options] pair
watchPlugins each entry, or the first item of a [name, options] pair
reporters each entry, skipping the built-in default, github-actions, and summary
moduleNameMapper each value, and each item of an array value
projects each inline project object, read with the same rules. String entries (paths) are skipped.

Behavior:

  • A specifier that is not a package name is skipped: a relative or absolute path, a <rootDir> path, a node: builtin, or a regex replacement such as $1. See toPackageName().
  • It does not load presets. { preset: '@repobuddy/jest/presets/ts' } gives @repobuddy/jest, not the packages that preset needs. Pass the preset object itself to list those.
  • A package referenced more than once appears once, with every specifier and field.

From the spec:

extract.extractPackages({ transform: fields.knownTransforms.tsJestCjs() })
// [
//   { name: 'jest-esm-transformer-2', specifiers: ['jest-esm-transformer-2'], fields: ['transform'] },
//   { name: 'ts-jest', specifiers: ['ts-jest'], fields: ['transform'] },
// ]
extract.extractPackages({ watchPlugins: fields.watchPlugins })
// [
//   { name: 'jest-watch-suspend', specifiers: ['jest-watch-suspend'], fields: ['watchPlugins'] },
//   { name: 'jest-watch-toggle-config', specifiers: ['jest-watch-toggle-config'], fields: ['watchPlugins'] },
//   {
//     name: 'jest-watch-typeahead',
//     specifiers: ['jest-watch-typeahead/filename', 'jest-watch-typeahead/testname'],
//     fields: ['watchPlugins'],
//   },
// ]
extract.extractPackages({ reporters: ['default', 'github-actions', 'summary', ['jest-junit', {}]] })
// [{ name: 'jest-junit', specifiers: ['jest-junit'], fields: ['reporters'] }]
extract.extractPackages({
  projects: ['<rootDir>/packages/*', { displayName: 'node', testEnvironment: 'node' }],
  watchPlugins: ['jest-watch-suspend'],
}).map((p) => p.name)
// ['jest-environment-node', 'jest-watch-suspend']

List what a preset needs by passing the preset object:

import preset from '@repobuddy/jest/presets/ts-esm'
import { extract } from '@repobuddy/jest'


extract.extractPackages(preset).map((p) => p.name)
// ['@swc/jest', 'jest-environment-node']

toPackageName()

Section titled “toPackageName()”

Returns the npm package name of a module specifier.

function toPackageName(specifier: string): string | undefined
Parameter Type Default Effect
specifier string required A module specifier as written in a config.

Returns the package name, or undefined when the specifier does not name a package.

From the spec:

Input Output
'ts-jest' 'ts-jest'
'jest-watch-typeahead/filename' 'jest-watch-typeahead'
'@swc/jest' '@swc/jest'
'@repobuddy/jest/presets/ts' '@repobuddy/jest'
'./setup.ts', '../setup.ts', '/abs/setup.ts', '<rootDir>/setup.ts' undefined
'$1' undefined
'node:path' undefined
'' undefined
'@swc' undefined

The name must be a valid lowercase npm name. 'Foo' returns undefined.

ExtractedPackage

Section titled “ExtractedPackage”
type ExtractedPackage = {
  name: string // the package name, such as 'jest-watch-typeahead'
  specifiers: string[] // the specifiers as written, such as ['jest-watch-typeahead/filename']
  fields: string[] // the config fields that reference it, such as ['watchPlugins']
}
Section titled “Related”