@eslint/plugin-kit 0.7.3

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 pkg:npm/%40eslint/plugin-kit@0.7.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40eslint/plugin-kit@0.7.3

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:aa22afeae0a8c8d841931c50b337b704be8f30636ff10a45ffb00dad2e90911d","contract":["assert TextSourceCodeBase subclass implements traverse generator yielding VisitNodeStep and CallMethodStep","assert TextSourceCodeBase supports position-style AST nodes for getLoc and getRange","assert TextSourceCodeBase constructor accepts custom lineEndingPattern for CRLF line splitting","assert TextSourceCodeBase default traverse and getParent methods throw Not implemented Error","assert TextSourceCodeBase getLocFromIndex and getIndexFromLoc throw RangeError on out-of-range coordinates","assert TextSourceCodeBase.getAncestors throws TypeError when node argument is missing"],"goal":"verify pkg:npm/%40eslint/plugin-kit@0.7.3","kind":"HOW","packages":["pkg:npm/%40eslint/plugin-kit@0.7.3"],"schemaVersion":1},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40eslint/plugin-kit@0.7.3"],"schemaVersion":1,"subject":"pkg:npm/%40eslint/plugin-kit@0.7.3","verifierAdapter":"node-typescript@1"}

const {
  TextSourceCodeBase,
  VisitNodeStep,
  CallMethodStep,
} = require('@eslint/plugin-kit');

/**
 * Custom SourceCode class supporting custom AST traversal and position-style AST nodes.
 */
class MarkdownSourceCode extends TextSourceCodeBase {
  #parents = new Map();

  /**
   * Returns the parent of the given AST node.
   * @param {object} node - AST node.
   * @returns {object|undefined} Parent node.
   */
  getParent(node) {
    return this.#parents.get(node);
  }

  /**
   * Sets the parent of a node.
   * @param {object} node - Child node.
   * @param {object} parent - Parent node.
   */
  setParent(node, parent) {
    this.#parents.set(node, parent);
  }

  /**
   * Traverses the AST in document order yielding VisitNodeStep and CallMethodStep steps.
   * @returns {Iterable<import('@eslint/plugin-kit').TraversalStep>} Traversal steps.
   */
  *traverse() {
    // Visit root node (enter)
    yield new VisitNodeStep({
      target: this.ast,
      phase: 1,
      args: [this.ast, null],
    });

    if (Array.isArray(this.ast.children)) {
      for (const child of this.ast.children) {
        this.setParent(child, this.ast);

        // Visit child node (enter)
        yield new VisitNodeStep({
          target: child,
          phase: 1,
          args: [child, this.ast],
        });

        // Call visitor method for child type
        yield new CallMethodStep({
          target: `on${child.type}`,
          args: [child],
        });

        // Visit child node (exit)
        yield new VisitNodeStep({
          target: child,
          phase: 2,
          args: [child, this.ast],
        });
      }
    }

    // Visit root node (exit)
    yield new VisitNodeStep({
      target: this.ast,
      phase: 2,
      args: [this.ast, null],
    });
  }
}

/**
 * Default SourceCode class without overrides to verify base class default contracts.
 */
class DefaultSourceCode extends TextSourceCodeBase {}

module.exports = {
  TextSourceCodeBase,
  VisitNodeStep,
  CallMethodStep,
  MarkdownSourceCode,
  DefaultSourceCode,
};

{
  "name": "sample-eslint-plugin-kit",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-eslint-plugin-kit",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@eslint/plugin-kit": "0.7.3"
      }
    },
    "node_modules/@eslint/core": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/@eslint/core/-/core-1.2.1.tgz",
      "integrity": "sha512-MwcE1P+AZ4C6DWlpin/OmOA54mmIZ/+xZuJiQd4SyB29oAJjN30UW9wkKNptW2ctp4cEsvhlLY/CsQ1uoHDloQ==",
      "license": "Apache-2.0",
      "dependencies": {
        "@types/json-schema": "^7.0.15"
      },
      "engines": {
        "node": "^20.19.0 || ^22.13.0 || >=24"
      }
    },
    "node_modules/@eslint/plugin-kit": {
      "version": "0.7.3",
      "resolved": "https://registry.npmjs.org/@eslint/plugin-kit/-/plugin-kit-0.7.3.tgz",
      "integrity": "sha512-IkO+/KEUvwbVpiURZg+P7zF74z5Jxe0UgJxVni+RtoHQ6IZieXaO02kmadomap/q+l6bc/jdPGGqTjhuZnuz1Q==",
      "license": "Apache-2.0",
      "dependencies": {
        "@eslint/core": "^1.2.1",
        "levn": "^0.4.1"
      },
      "engines": {
        "node": "^20.19.0 || ^22.13.0 || >=24"
      }
    },
    "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"
    },
    "node_modules/levn": {
      "version": "0.4.1",
      "resolved": "https://registry.npmjs.org/levn/-/levn-0.4.1.tgz",
      "integrity": "sha512-+bT2uH4E5LGE7h/n3evcS/sQlJXCpIp6ym8OWJ5eV6+67Dsql/LaaT7qJBAt2rzfoa/5QBGBhxDix1dMt2kQKQ==",
      "license": "MIT",
      "dependencies": {
        "prelude-ls": "^1.2.1",
        "type-check": "~0.4.0"
      },
      "engines": {
        "node": ">= 0.8.0"
      }
    },
    "node_modules/prelude-ls": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",
      "integrity": "sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.8.0"
      }
    },
    "node_modules/type-check": {
      "version": "0.4.0",
      "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.4.0.tgz",
      "integrity": "sha512-XleUoc9uwGXqjWwXaUTZAmzMcFZ5858QA2vvx1Ur5xIcixXIP+8LnFDgRplU30us6teqdlskFfu+ae4K79Ooew==",
      "license": "MIT",
      "dependencies": {
        "prelude-ls": "^1.2.1"
      },
      "engines": {
        "node": ">= 0.8.0"
      }
    }
  }
}

{
  "name": "sample-eslint-plugin-kit",
  "version": "1.0.0",
  "description": "Clean-room sample verifying @eslint/plugin-kit traversal and position-style AST source code",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "@eslint/plugin-kit": "0.7.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40eslint/plugin-kit@0.7.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40eslint/plugin-kit@0.7.3"
  ]
}

import assert from 'node:assert';
import {
  TextSourceCodeBase,
  VisitNodeStep,
  CallMethodStep,
  MarkdownSourceCode,
  DefaultSourceCode,
} from '../index.js';

// 1. Verify TextSourceCodeBase subclass implements traverse generator yielding VisitNodeStep and CallMethodStep
const headingNode = {
  type: 'Heading',
  position: {
    start: { line: 1, column: 1, offset: 0 },
    end: { line: 1, column: 14, offset: 13 },
  },
};
const paragraphNode = {
  type: 'Paragraph',
  position: {
    start: { line: 3, column: 1, offset: 15 },
    end: { line: 3, column: 16, offset: 30 },
  },
};
const docAst = {
  type: 'Document',
  position: {
    start: { line: 1, column: 1, offset: 0 },
    end: { line: 3, column: 16, offset: 30 },
  },
  children: [headingNode, paragraphNode],
};
const docText = '# Hello World\n\nParagraph text.\n';

const markdownSource = new MarkdownSourceCode({
  ast: docAst,
  text: docText,
});

const steps = Array.from(markdownSource.traverse());
assert.strictEqual(steps.length, 8);

// Root node enter
assert.strictEqual(steps[0].type, 'visit');
assert.strictEqual(steps[0].kind, 1);
assert.strictEqual(steps[0].phase, 1);
assert.strictEqual(steps[0].target, docAst);

// First child enter
assert.strictEqual(steps[1].type, 'visit');
assert.strictEqual(steps[1].kind, 1);
assert.strictEqual(steps[1].phase, 1);
assert.strictEqual(steps[1].target, headingNode);

// First child visitor method call
assert.strictEqual(steps[2].type, 'call');
assert.strictEqual(steps[2].kind, 2);
assert.strictEqual(steps[2].target, 'onHeading');
assert.deepStrictEqual(steps[2].args, [headingNode]);

// First child exit
assert.strictEqual(steps[3].type, 'visit');
assert.strictEqual(steps[3].phase, 2);
assert.strictEqual(steps[3].target, headingNode);

// Parent links established during traversal
assert.strictEqual(markdownSource.getParent(headingNode), docAst);
assert.strictEqual(markdownSource.getParent(paragraphNode), docAst);

// 2. Verify TextSourceCodeBase supports position-style AST nodes for getLoc and getRange
const headingLoc = markdownSource.getLoc(headingNode);
assert.deepStrictEqual(headingLoc, {
  start: { line: 1, column: 1, offset: 0 },
  end: { line: 1, column: 14, offset: 13 },
});

const headingRange = markdownSource.getRange(headingNode);
assert.deepStrictEqual(headingRange, [0, 13]);
assert.strictEqual(markdownSource.getText(headingNode), '# Hello World');

const paragraphRange = markdownSource.getRange(paragraphNode);
assert.deepStrictEqual(paragraphRange, [15, 30]);
assert.strictEqual(markdownSource.getText(paragraphNode), 'Paragraph text.');

// 3. Verify TextSourceCodeBase constructor accepts custom lineEndingPattern for CRLF line splitting
const crlfDocText = 'alpha\r\nbeta\r\ngamma';
const crlfSource = new DefaultSourceCode({
  text: crlfDocText,
  ast: {
    type: 'Program',
    loc: {
      start: { line: 1, column: 0 },
      end: { line: 3, column: 5 },
    },
  },
  lineEndingPattern: /\r\n/u,
});
assert.strictEqual(crlfSource.lines.length, 3);
assert.strictEqual(crlfSource.lines[0], 'alpha');
assert.strictEqual(crlfSource.lines[1], 'beta');
assert.strictEqual(crlfSource.lines[2], 'gamma');

// 4. Verify TextSourceCodeBase default traverse and getParent methods throw Not implemented Error
const defaultSource = new DefaultSourceCode({
  text: 'sample text',
  ast: {
    type: 'Program',
    loc: {
      start: { line: 1, column: 0 },
      end: { line: 1, column: 11 },
    },
  },
});
assert.throws(() => defaultSource.getParent({}), {
  name: 'Error',
  message: 'Not implemented.',
});
assert.throws(() => defaultSource.traverse(), {
  name: 'Error',
  message: 'Not implemented.',
});

// 5. Verify TextSourceCodeBase getLocFromIndex and getIndexFromLoc throw RangeError on out-of-range coordinates
assert.throws(() => defaultSource.getLocFromIndex(-1), {
  name: 'RangeError',
});
assert.throws(() => defaultSource.getLocFromIndex(999), {
  name: 'RangeError',
});
assert.throws(() => defaultSource.getIndexFromLoc({ line: 0, column: 0 }), {
  name: 'RangeError',
});
assert.throws(() => defaultSource.getIndexFromLoc({ line: 5, column: 0 }), {
  name: 'RangeError',
});

// 6. Verify TextSourceCodeBase.getAncestors throws TypeError when node argument is missing
assert.throws(() => defaultSource.getAncestors(), {
  name: 'TypeError',
  message: 'Missing required argument: node.',
});

console.log('All @eslint/plugin-kit contract assertions passed successfully.');