@arx-tools/config

The shared development tooling of the arx-tools libraries: the xo and prettier configuration, the tsconfig base and the test runner. Every library uses the same conventions, so they live here instead of being copied into each repository.

It is development tooling only — none of it ends up in the published library code.

Contents

export	what it is
@arx-tools/config	createXoConfig() and the shared rules of the xo configuration
@arx-tools/config/prettier	the shared prettier options
@arx-tools/config/tsconfig.base.json	the shared compilerOptions of the TypeScript projects
arx-lib-test (bin)	the node:test runner: a single line per test with rounded durations, and it fails when no test ran

Requirements

The tooling runs on the same Node.js version as the libraries' development environment: Node.js >= 22.18, because the sources and the tests run directly through type stripping.

Usage

The xo configuration

// xo.config.ts
import { createXoConfig } from '@arx-tools/config'

export default createXoConfig()

The factory assumes the folder layout of the libraries (src/, tests/, scripts/ with their own tsconfig.src.json, tsconfig.tests.json and tsconfig.scripts.json). Anything different can be passed in:

export default createXoConfig({
  rootDir: import.meta.dirname,
  sourceProject: './tsconfig.app.json',
  testProject: './tsconfig.spec.json',
  scriptProject: './tsconfig.tooling.json',
})

The shared rule set is exported as rules as well, so a repository can extend a copy of it instead of using the factory.

The prettier configuration

Prettier reads the package name from the prettier field of package.json:

{
  "prettier": "@arx-tools/config/prettier"
}

xo formats with prettier through its own parser, so it picks up the same options.

The TypeScript base

{
  "extends": "@arx-tools/config/tsconfig.base.json",
  "compilerOptions": {
    "rootDir": "./src",
    "outDir": "./dist"
  },
  "include": ["src/**/*"]
}

The base contains the target, the module settings, strict, and the flags which make the sources runnable without a build: allowImportingTsExtensions, rewriteRelativeImportExtensions, verbatimModuleSyntax and erasableSyntaxOnly.

The test runner

{
  "scripts": {
    "test": "arx-lib-test"
  }
}

The runner starts node --test with the tests/**/*.spec.ts pattern (any other pattern can be passed as the first argument), prints one line per test through its own reporter and fails when no test had been executed — node --test exits with zero for an empty glob, which makes a broken pattern look like a green suite.

The reporter is configured by two environment variables:

variable	values	default
TEST_REPORT_FORMAT	flat (one line per test), tree (grouped under the suites)	flat
TEST_REPORT_DURATION	auto (milliseconds below a second, seconds above it, four significant digits), ms, none	auto

Development of this package

The package compiles its TypeScript sources into dist/ with tsc, so the consumers get JavaScript and declarations from node_modules (the type stripping of Node.js does not apply there).

command	what it does
npm install	installs the dependencies
npm run lint	check code against the pre-defined coding guidelines
npm run typecheck	type checks the sources, the tests and the config
npm test	builds nothing, runs the compiled runner against the tests
npm run build	compiles dist/ and rewrites the .ts extensions in the declarations

License

MIT