@babel/types 7.29.8: blockStatement

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 @babel/types.blockStatement in pkg:npm/%40babel/types@7.29.8
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/types@7.29.8
Demonstrate these symbols/APIs:
  - @babel/types.blockStatement

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.

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{
  "name": "sample-babel-types-block-statement",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-babel-types-block-statement",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@babel/types": "7.29.8"
      }
    },
    "node_modules/@babel/helper-string-parser": {
      "version": "7.29.7",
      "resolved": "https://registry.npmjs.org/@babel/helper-string-parser/-/helper-string-parser-7.29.7.tgz",
      "integrity": "sha512-Pb5ijPrZ89GDH8223L4UP8i6QApWxs04RbPQJTeWDV0/keR2E36MeKnyr6LYmUUvqRRI+Iv87SuF1W6ErINzYw==",
      "license": "MIT",
      "engines": {
        "node": ">=6.9.0"
      }
    },
    "node_modules/@babel/helper-validator-identifier": {
      "version": "7.29.7",
      "resolved": "https://registry.npmjs.org/@babel/helper-validator-identifier/-/helper-validator-identifier-7.29.7.tgz",
      "integrity": "sha512-qehxGkRj55h/ff8EMaJ+cYhyaKlHIxqYDn682wQD7RNp9UujOQsHog2uS0r2vzr4pW+sXf90NeeayjcNaX3fFg==",
      "license": "MIT",
      "engines": {
        "node": ">=6.9.0"
      }
    },
    "node_modules/@babel/types": {
      "version": "7.29.8",
      "resolved": "https://registry.npmjs.org/@babel/types/-/types-7.29.8.tgz",
      "integrity": "sha512-Vj1jF3cPfxg7OAfoI7QnVKLoILlm2JF9pnVHrX8qx7AHMiYWT+NDAA7jChlNgRS4WTLc/fD1lXLmPixluj+3Gg==",
      "license": "MIT",
      "dependencies": {
        "@babel/helper-string-parser": "^7.29.7",
        "@babel/helper-validator-identifier": "^7.29.7"
      },
      "engines": {
        "node": ">=6.9.0"
      }
    }
  }
}

{
  "name": "sample-babel-types-block-statement",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of @babel/types.blockStatement",
  "main": "src/index.js",
  "license": "MIT-0",
  "dependencies": {
    "@babel/types": "7.29.8"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @babel/types.blockStatement in pkg:npm/%40babel/types@7.29.8",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/types@7.29.8"
  ],
  "symbols": [
    "@babel/types.blockStatement"
  ]
}

const t = require('@babel/types');

/**
 * Creates a BlockStatement AST node containing statements and optional directives.
 * @param {Array<object>} body
 * @param {Array<object>} [directives]
 * @returns {object}
 */
function createBlockStatement(body, directives) {
  return t.blockStatement(body, directives);
}

/**
 * Creates an empty BlockStatement AST node.
 * @returns {object}
 */
function createEmptyBlockStatement() {
  return t.blockStatement([]);
}

/**
 * Checks if a node is a BlockStatement AST node.
 * @param {object} node
 * @param {object} [opts]
 * @returns {boolean}
 */
function isBlockStatementNode(node, opts) {
  return t.isBlockStatement(node, opts);
}

/**
 * Asserts that a node is a BlockStatement AST node, throwing an error otherwise.
 * @param {object} node
 * @param {object} [opts]
 */
function assertBlockStatementNode(node, opts) {
  t.assertBlockStatement(node, opts);
}

/**
 * Creates a FunctionDeclaration AST node with a block statement body.
 * @param {string|object} id
 * @param {Array<object>} params
 * @param {Array<object>} bodyStatements
 * @returns {object}
 */
function createFunctionWithBlock(id, params, bodyStatements) {
  const identifierNode = typeof id === 'string' ? t.identifier(id) : id;
  const block = t.blockStatement(bodyStatements);
  return t.functionDeclaration(identifierNode, params, block);
}

/**
 * Creates an IfStatement AST node with block statement branches.
 * @param {object} test
 * @param {Array<object>} consequentStatements
 * @param {Array<object>} [alternateStatements]
 * @returns {object}
 */
function createIfWithBlocks(test, consequentStatements, alternateStatements) {
  const consequentBlock = t.blockStatement(consequentStatements);
  const alternateBlock = alternateStatements ? t.blockStatement(alternateStatements) : null;
  return t.ifStatement(test, consequentBlock, alternateBlock);
}

/**
 * Creates a TryStatement AST node with block statements for try, catch, and optional finally blocks.
 * @param {Array<object>} tryStatements
 * @param {string} [catchParamName]
 * @param {Array<object>} [catchStatements]
 * @param {Array<object>} [finalizerStatements]
 * @returns {object}
 */
function createTryCatchWithBlocks(tryStatements, catchParamName, catchStatements, finalizerStatements) {
  const tryBlock = t.blockStatement(tryStatements);
  let handler = null;
  if (catchParamName || catchStatements) {
    const param = catchParamName ? t.identifier(catchParamName) : null;
    const handlerBlock = t.blockStatement(catchStatements || []);
    handler = t.catchClause(param, handlerBlock);
  }
  const finalizerBlock = finalizerStatements ? t.blockStatement(finalizerStatements) : null;
  return t.tryStatement(tryBlock, handler, finalizerBlock);
}

/**
 * Clones a BlockStatement AST node.
 * @param {object} node
 * @returns {object}
 */
function cloneBlockStatement(node) {
  return t.cloneNode(node);
}

module.exports = {
  t,
  createBlockStatement,
  createEmptyBlockStatement,
  isBlockStatementNode,
  assertBlockStatementNode,
  createFunctionWithBlock,
  createIfWithBlocks,
  createTryCatchWithBlocks,
  cloneBlockStatement,
};

import assert from 'node:assert';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);
const {
  t,
  createBlockStatement,
  createEmptyBlockStatement,
  isBlockStatementNode,
  assertBlockStatementNode,
  createFunctionWithBlock,
  createIfWithBlocks,
  createTryCatchWithBlocks,
  cloneBlockStatement,
} = require('../src/index.js');

async function runContract() {
  // 1. types.blockStatement creates a BlockStatement AST node with an array of statement nodes and directives
  const returnStmt = t.returnStatement(t.numericLiteral(42));
  const exprStmt = t.expressionStatement(t.stringLiteral('hello'));
  const directive = t.directive(t.directiveLiteral('use strict'));

  const blockWithDirectives = createBlockStatement([exprStmt, returnStmt], [directive]);
  assert.strictEqual(blockWithDirectives.type, 'BlockStatement');
  assert.strictEqual(blockWithDirectives.body.length, 2);
  assert.strictEqual(blockWithDirectives.body[0], exprStmt);
  assert.strictEqual(blockWithDirectives.body[1], returnStmt);
  assert.strictEqual(blockWithDirectives.directives.length, 1);
  assert.strictEqual(blockWithDirectives.directives[0].value.value, 'use strict');

  // 2. types.blockStatement creates an empty block statement when called with an empty statements array
  const emptyBlock = createEmptyBlockStatement();
  assert.strictEqual(emptyBlock.type, 'BlockStatement');
  assert.strictEqual(Array.isArray(emptyBlock.body), true);
  assert.strictEqual(emptyBlock.body.length, 0);
  assert.strictEqual(Array.isArray(emptyBlock.directives), true);
  assert.strictEqual(emptyBlock.directives.length, 0);

  // 3. types.isBlockStatement returns true for BlockStatement nodes with optional property matching and false for non-BlockStatement nodes
  assert.strictEqual(isBlockStatementNode(blockWithDirectives), true);
  assert.strictEqual(isBlockStatementNode(emptyBlock), true);
  assert.strictEqual(isBlockStatementNode(t.identifier('foo')), false);
  assert.strictEqual(isBlockStatementNode(t.numericLiteral(123)), false);
  assert.strictEqual(isBlockStatementNode(null), false);
  assert.strictEqual(isBlockStatementNode(undefined), false);

  // 4. types.assertBlockStatement succeeds for valid BlockStatement nodes and throws an Error for non-BlockStatement nodes
  assertBlockStatementNode(blockWithDirectives);
  assertBlockStatementNode(emptyBlock);
  assert.throws(
    () => assertBlockStatementNode(t.identifier('invalid')),
    (err) => err instanceof Error,
    'assertBlockStatement on non-BlockStatement node must throw'
  );
  assert.throws(
    () => assertBlockStatementNode(null),
    (err) => err instanceof Error,
    'assertBlockStatement on null must throw'
  );

  // 5. BlockStatement nodes integrate as the body of control flow and function constructs such as FunctionDeclaration, IfStatement, and TryStatement
  const funcDecl = createFunctionWithBlock('compute', [t.identifier('x')], [returnStmt]);
  assert.strictEqual(funcDecl.type, 'FunctionDeclaration');
  assert.strictEqual(funcDecl.id.name, 'compute');
  assert.strictEqual(funcDecl.body.type, 'BlockStatement');
  assert.strictEqual(funcDecl.body.body[0], returnStmt);

  const ifStmt = createIfWithBlocks(
    t.booleanLiteral(true),
    [exprStmt],
    [returnStmt]
  );
  assert.strictEqual(ifStmt.type, 'IfStatement');
  assert.strictEqual(ifStmt.consequent.type, 'BlockStatement');
  assert.strictEqual(ifStmt.alternate.type, 'BlockStatement');

  const tryCatchStmt = createTryCatchWithBlocks(
    [exprStmt],
    'err',
    [returnStmt],
    [t.expressionStatement(t.numericLiteral(0))]
  );
  assert.strictEqual(tryCatchStmt.type, 'TryStatement');
  assert.strictEqual(tryCatchStmt.block.type, 'BlockStatement');
  assert.strictEqual(tryCatchStmt.handler.type, 'CatchClause');
  assert.strictEqual(tryCatchStmt.handler.body.type, 'BlockStatement');
  assert.strictEqual(tryCatchStmt.finalizer.type, 'BlockStatement');

  // 6. types.cloneNode produces an independent equivalent copy of a BlockStatement node
  const cloned = cloneBlockStatement(blockWithDirectives);
  assert.notStrictEqual(cloned, blockWithDirectives, 'cloned node must have separate object identity');
  assert.strictEqual(cloned.type, 'BlockStatement');
  assert.strictEqual(t.isNodesEquivalent(cloned, blockWithDirectives), true);

  console.log('All contract assertions passed successfully.');
}

runContract().catch((err) => {
  console.error('Contract test failed:', err);
  process.exit(1);
});