@eslint/config-helpers 0.4.2: defineConfig

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify @eslint/config-helpers.defineConfig in pkg:npm/%40eslint/config-helpers@0.4.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40eslint/config-helpers@0.4.2
Demonstrate these symbols/APIs:
  - @eslint/config-helpers.defineConfig

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:b3ddeee85533a56bd9cc8705874aaebc89716d02a1560cc25883f6f8bc8b6e70","contract":["defineConfig accepts a single configuration object or array and normalizes to an array","defineConfig recursively flattens nested configuration arrays while preserving object order","defineConfig extends configuration objects by combining files patterns and appending ignores","defineConfig resolves and scopes plugin configs referenced by string in extends","defineConfig throws TypeError when called with invalid arguments such as null, primitives, or undefined"],"goal":"verify @eslint/config-helpers.defineConfig in pkg:npm/%40eslint/config-helpers@0.4.2","kind":"HOW","packages":["pkg:npm/%40eslint/config-helpers@0.4.2"],"schemaVersion":1,"symbols":["@eslint/config-helpers.defineConfig"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40eslint/config-helpers@0.4.2"],"schemaVersion":1,"subject":"pkg:npm/%40eslint/config-helpers@0.4.2","symbols":["@eslint/config-helpers.defineConfig"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-eslint-config-helpers",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-eslint-config-helpers",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@eslint/config-helpers": "0.4.2"
      }
    },
    "node_modules/@eslint/config-helpers": {
      "version": "0.4.2",
      "resolved": "https://registry.npmjs.org/@eslint/config-helpers/-/config-helpers-0.4.2.tgz",
      "integrity": "sha512-gBrxN88gOIf3R7ja5K9slwNayVcZgK6SOUORm2uBzTeIEfeVaIhOpCtTox3P6R7o2jLFwLFTLnC7kU/RGcYEgw==",
      "license": "Apache-2.0",
      "dependencies": {
        "@eslint/core": "^0.17.0"
      },
      "engines": {
        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
      }
    },
    "node_modules/@eslint/core": {
      "version": "0.17.0",
      "resolved": "https://registry.npmjs.org/@eslint/core/-/core-0.17.0.tgz",
      "integrity": "sha512-yL/sLrpmtDaFEiUj1osRP4TI2MDz1AddJL+jZ7KSqvBuliN4xqYY54IfdN8qD8Toa6g1iloph1fxQNkjOxrrpQ==",
      "license": "Apache-2.0",
      "dependencies": {
        "@types/json-schema": "^7.0.15"
      },
      "engines": {
        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
      }
    },
    "node_modules/@types/json-schema": {
      "version": "7.0.15",
      "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.15.tgz",
      "integrity": "sha512-5+fP8P8MFNC+AyZCDxrB2pkZFPGzqQWUzpSeuuVLvm8VMcorNYavBqoFcxK8bQz4Qsbn4oUEEem4wDLfcysGHA==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-eslint-config-helpers",
  "version": "1.0.0",
  "private": true,
  "license": "MIT-0",
  "dependencies": {
    "@eslint/config-helpers": "0.4.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @eslint/config-helpers.defineConfig in pkg:npm/%40eslint/config-helpers@0.4.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40eslint/config-helpers@0.4.2"
  ],
  "symbols": [
    "@eslint/config-helpers.defineConfig"
  ]
}

import assert from "node:assert/strict";
import { defineConfig } from "@eslint/config-helpers";

// 1. defineConfig accepts a single configuration object or array and normalizes to an array
const singleConfig = { name: "my-base", rules: { semi: "error" } };
const singleResult = defineConfig(singleConfig);
assert.equal(Array.isArray(singleResult), true);
assert.equal(singleResult.length, 1);
assert.equal(singleResult[0].name, "my-base");
assert.equal(singleResult[0].rules.semi, "error");

// 2. defineConfig recursively flattens nested configuration arrays while preserving object order
const configA = { name: "cfg-a", rules: { "no-unused-vars": "error" } };
const configB = { name: "cfg-b", files: ["src/**/*.js"] };
const configC = { name: "cfg-c", rules: { "no-debugger": "warn" } };
const flattened = defineConfig([configA, [configB, [configC]]]);
assert.equal(flattened.length, 3);
assert.equal(flattened[0].name, "cfg-a");
assert.equal(flattened[1].name, "cfg-b");
assert.deepEqual(flattened[1].files, ["src/**/*.js"]);
assert.equal(flattened[2].name, "cfg-c");

// 3. defineConfig extends configuration objects by combining files patterns and appending ignores
const subConfig = {
  name: "sub-config",
  files: ["*.ts"],
  ignores: ["temp/**"],
  rules: { "no-var": "error" },
};
const parentConfig = defineConfig({
  name: "root-config",
  files: ["src/**"],
  ignores: ["dist/**"],
  extends: [subConfig],
  rules: { eqeqeq: "error" },
});
assert.equal(parentConfig.length, 2);
assert.equal(parentConfig[0].name, "root-config > sub-config");
assert.deepEqual(parentConfig[0].files, [["src/**", "*.ts"]]);
assert.deepEqual(parentConfig[0].ignores, ["dist/**", "temp/**"]);
assert.equal(parentConfig[0].rules["no-var"], "error");
assert.equal(parentConfig[1].name, "root-config");
assert.equal(parentConfig[1].rules.eqeqeq, "error");

// 4. defineConfig resolves and scopes plugin configs referenced by string in extends
const mockPlugin = {
  meta: { name: "eslint-plugin-sample", namespace: "sample" },
  configs: {
    recommended: {
      rules: { "sample/no-bad-logic": "error" },
    },
  },
};
const pluginResult = defineConfig({
  name: "consumer-config",
  plugins: { customPlugin: mockPlugin },
  extends: ["customPlugin/recommended"],
});
assert.equal(pluginResult.length, 2);
assert.equal(
  pluginResult[0].name,
  "consumer-config > customPlugin/recommended"
);
assert.equal(pluginResult[0].rules["customPlugin/no-bad-logic"], "error");

// 5. defineConfig throws TypeError when called with invalid arguments such as null, primitives, or undefined
assert.throws(() => defineConfig(), { name: "TypeError" });
assert.throws(() => defineConfig(null), { name: "TypeError" });
assert.throws(() => defineConfig("invalid"), { name: "TypeError" });
assert.throws(() => defineConfig(123), { name: "TypeError" });