estraverse 5.3.0

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/estraverse@5.3.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/estraverse@5.3.0

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:sha256:613ab59b6065d50477b3788ce12f3f170ebc51d25d0593ad004c9797df885958","contract":["traverse visits AST nodes in depth-first order invoking enter and leave callbacks","returning VisitorOption.Skip from enter skips child nodes of current AST node","returning VisitorOption.Break terminates AST traversal immediately","replace modifies AST by substituting returned node in place of current node","returning VisitorOption.Remove from replace removes node from parent AST array","Syntax dictionary provides standard ESTree AST node type string constants","VisitorKeys mapping defines child traversal keys for ESTree AST node types","Controller class tracks traversal hierarchy and provides parents method"],"goal":"verify pkg:npm/estraverse@5.3.0","kind":"HOW","packages":["pkg:npm/estraverse@5.3.0"],"schemaVersion":1},"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/estraverse@5.3.0"],"schemaVersion":1,"subject":"pkg:npm/estraverse@5.3.0","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-estraverse",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-estraverse",
      "version": "1.0.0",
      "dependencies": {
        "estraverse": "5.3.0"
      }
    },
    "node_modules/estraverse": {
      "version": "5.3.0",
      "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-5.3.0.tgz",
      "integrity": "sha512-MMdARuVEQziNTeJD8DgMqmhwR11BRQ/cBP+pLtYdSTnf3MIO8fFeiINEbX36ZdNlfU/7A9f3gUw49B3oQsvwBA==",
      "license": "BSD-2-Clause",
      "engines": {
        "node": ">=4.0"
      }
    }
  }
}

{
  "name": "sample-estraverse",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "estraverse": "5.3.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/estraverse@5.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/estraverse@5.3.0"
  ]
}

import assert from 'node:assert/strict';
import estraverse from 'estraverse';

// 1. traverse visits AST nodes in depth-first order invoking enter and leave callbacks
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      {
        type: estraverse.Syntax.ExpressionStatement,
        expression: {
          type: estraverse.Syntax.BinaryExpression,
          operator: '+',
          left: { type: estraverse.Syntax.Identifier, name: 'a' },
          right: { type: estraverse.Syntax.Literal, value: 1 }
        }
      }
    ]
  };

  const entered = [];
  const left = [];
  estraverse.traverse(ast, {
    enter(node) {
      entered.push(node.type);
    },
    leave(node) {
      left.push(node.type);
    }
  });

  assert.deepEqual(entered, [
    'Program',
    'ExpressionStatement',
    'BinaryExpression',
    'Identifier',
    'Literal'
  ]);
  assert.deepEqual(left, [
    'Identifier',
    'Literal',
    'BinaryExpression',
    'ExpressionStatement',
    'Program'
  ]);
}

// 2. returning VisitorOption.Skip from enter skips child nodes of current AST node
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      {
        type: estraverse.Syntax.ExpressionStatement,
        expression: {
          type: estraverse.Syntax.BinaryExpression,
          operator: '+',
          left: { type: estraverse.Syntax.Identifier, name: 'a' },
          right: { type: estraverse.Syntax.Literal, value: 1 }
        }
      }
    ]
  };

  const visited = [];
  estraverse.traverse(ast, {
    enter(node) {
      visited.push(node.type);
      if (node.type === estraverse.Syntax.ExpressionStatement) {
        return estraverse.VisitorOption.Skip;
      }
    }
  });

  assert.deepEqual(visited, ['Program', 'ExpressionStatement']);
}

// 3. returning VisitorOption.Break terminates AST traversal immediately
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      {
        type: estraverse.Syntax.ExpressionStatement,
        expression: {
          type: estraverse.Syntax.BinaryExpression,
          operator: '+',
          left: { type: estraverse.Syntax.Identifier, name: 'a' },
          right: { type: estraverse.Syntax.Literal, value: 1 }
        }
      }
    ]
  };

  const visited = [];
  estraverse.traverse(ast, {
    enter(node) {
      visited.push(node.type);
      if (node.type === estraverse.Syntax.BinaryExpression) {
        return estraverse.VisitorOption.Break;
      }
    }
  });

  assert.deepEqual(visited, ['Program', 'ExpressionStatement', 'BinaryExpression']);
}

// 4. replace modifies AST by substituting returned node in place of current node
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      {
        type: estraverse.Syntax.Identifier,
        name: 'original'
      }
    ]
  };

  const result = estraverse.replace(ast, {
    enter(node) {
      if (node.type === estraverse.Syntax.Identifier && node.name === 'original') {
        return { type: estraverse.Syntax.Identifier, name: 'renamed' };
      }
    }
  });

  assert.equal(result.body[0].name, 'renamed');
}

// 5. returning VisitorOption.Remove from replace removes node from parent AST array
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      { type: estraverse.Syntax.Identifier, name: 'keepFirst' },
      { type: estraverse.Syntax.Identifier, name: 'deleteMe' },
      { type: estraverse.Syntax.Identifier, name: 'keepSecond' }
    ]
  };

  estraverse.replace(ast, {
    enter(node) {
      if (node.type === estraverse.Syntax.Identifier && node.name === 'deleteMe') {
        return estraverse.VisitorOption.Remove;
      }
    }
  });

  assert.equal(ast.body.length, 2);
  assert.deepEqual(
    ast.body.map((n) => n.name),
    ['keepFirst', 'keepSecond']
  );
}

// 6. Syntax dictionary provides standard ESTree AST node type string constants
{
  assert.equal(estraverse.Syntax.Program, 'Program');
  assert.equal(estraverse.Syntax.Identifier, 'Identifier');
  assert.equal(estraverse.Syntax.Literal, 'Literal');
  assert.equal(estraverse.Syntax.FunctionDeclaration, 'FunctionDeclaration');
  assert.equal(estraverse.Syntax.BlockStatement, 'BlockStatement');
}

// 7. VisitorKeys mapping defines child traversal keys for ESTree AST node types
{
  assert.ok(Array.isArray(estraverse.VisitorKeys.BinaryExpression));
  assert.deepEqual(estraverse.VisitorKeys.BinaryExpression, ['left', 'right']);
  assert.deepEqual(estraverse.VisitorKeys.IfStatement, ['test', 'consequent', 'alternate']);
}

// 8. Controller class tracks traversal hierarchy and provides parents method
{
  const ast = {
    type: estraverse.Syntax.Program,
    body: [
      {
        type: estraverse.Syntax.ExpressionStatement,
        expression: {
          type: estraverse.Syntax.Literal,
          value: 123
        }
      }
    ]
  };

  const controller = new estraverse.Controller();
  const parentTypes = [];
  controller.traverse(ast, {
    enter(node) {
      if (node.type === estraverse.Syntax.Literal) {
        parentTypes.push(...controller.parents().map((p) => p.type));
      }
    }
  });

  assert.deepEqual(parentTypes, ['Program', 'ExpressionStatement']);
}