@eslint/plugin-kit 0.7.3: VisitNodeStep

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 VisitNodeStep in 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
Demonstrate these symbols/APIs:
  - VisitNodeStep

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:d8e10980fa40ecf8fb5ba1ae26b3395af659e12a990e6e4500a4f35a75e435b3","contract":["instantiates VisitNodeStep with target AST node, traversal phase, and arguments array","exposes readonly type property set to 'visit' and numeric kind property set to 1","preserves target node, phase indicator, and argument array references","differentiates enter and exit traversal phases with phase values 1 and 2","dispatches enter and exit visitor handler calls based on target node type and step phase"],"goal":"verify VisitNodeStep in pkg:npm/%40eslint/plugin-kit@0.7.3","kind":"HOW","packages":["pkg:npm/%40eslint/plugin-kit@0.7.3"],"schemaVersion":1,"symbols":["VisitNodeStep"]},"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/plugin-kit@0.7.3"],"schemaVersion":1,"subject":"pkg:npm/%40eslint/plugin-kit@0.7.3","symbols":["VisitNodeStep"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-eslint-plugin-kit-visit-node-step",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-eslint-plugin-kit-visit-node-step",
      "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-visit-node-step",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "@eslint/plugin-kit": "0.7.3"
  }
}

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

import assert from "node:assert/strict";
import { VisitNodeStep } from "@eslint/plugin-kit";

// 1. instantiates VisitNodeStep with target AST node, traversal phase, and arguments array
const mockParent = { type: "Program", body: [] };
const mockNode = { type: "Identifier", name: "foo" };
const stepEnter = new VisitNodeStep({
  target: mockNode,
  phase: 1,
  args: [mockNode, mockParent],
});
assert.ok(stepEnter instanceof VisitNodeStep, "stepEnter must be an instance of VisitNodeStep");

// 2. exposes readonly type property set to 'visit' and numeric kind property set to 1
assert.equal(stepEnter.type, "visit", "stepEnter.type must be 'visit'");
assert.equal(stepEnter.kind, 1, "stepEnter.kind must be numeric 1");

// 3. preserves target node, phase indicator, and argument array references
assert.equal(stepEnter.target, mockNode, "stepEnter.target must match target node reference");
assert.equal(stepEnter.phase, 1, "stepEnter.phase must be 1");
assert.equal(stepEnter.args.length, 2, "stepEnter.args length must be 2");
assert.equal(stepEnter.args[0], mockNode, "stepEnter.args[0] must match mockNode");
assert.equal(stepEnter.args[1], mockParent, "stepEnter.args[1] must match mockParent");

const stepEmptyArgs = new VisitNodeStep({
  target: mockNode,
  phase: 2,
  args: [],
});
assert.equal(stepEmptyArgs.phase, 2);
assert.deepEqual(stepEmptyArgs.args, []);

// 4. differentiates enter and exit traversal phases with phase values 1 and 2
const stepExit = new VisitNodeStep({
  target: mockNode,
  phase: 2,
  args: [mockNode, mockParent],
});
assert.equal(stepEnter.phase, 1, "phase 1 represents enter phase");
assert.equal(stepExit.phase, 2, "phase 2 represents exit phase");
assert.notEqual(stepEnter.phase, stepExit.phase, "enter and exit phases must differ");

// 5. dispatches enter and exit visitor handler calls based on target node type and step phase
const visited = [];
const ruleVisitor = {
  Identifier(...args) {
    visited.push({ hook: "Identifier:enter", args });
  },
  "Identifier:exit"(...args) {
    visited.push({ hook: "Identifier:exit", args });
  },
};

const steps = [
  new VisitNodeStep({ target: mockNode, phase: 1, args: [mockNode, mockParent] }),
  new VisitNodeStep({ target: mockNode, phase: 2, args: [mockNode, mockParent] }),
];

for (const step of steps) {
  assert.equal(step.type, "visit");
  assert.equal(step.kind, 1);
  const hookName = step.phase === 1 ? step.target.type : `${step.target.type}:exit`;
  if (typeof ruleVisitor[hookName] === "function") {
    ruleVisitor[hookName](...step.args);
  }
}

assert.equal(visited.length, 2, "visitor should have received 2 dispatches");
assert.deepEqual(visited[0], {
  hook: "Identifier:enter",
  args: [mockNode, mockParent],
});
assert.deepEqual(visited[1], {
  hook: "Identifier:exit",
  args: [mockNode, mockParent],
});

console.log("VisitNodeStep contract tests passed successfully.");