@babel/types 7.29.8: isBlockStatement

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.isBlockStatement 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.isBlockStatement

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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      "license": "MIT",
      "engines": {
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      "license": "MIT",
      "dependencies": {
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      "engines": {
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{
  "name": "sample-babel-types-is-block-statement",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "@babel/types": "7.29.8"
  }
}

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

import * as t from "@babel/types";

export function createBlock(statements = [], directives = []) {
  return t.blockStatement(statements, directives);
}

export function checkIsBlockStatement(node, opts) {
  return t.isBlockStatement(node, opts);
}

export function createEmptyBlock() {
  return t.blockStatement([]);
}

import assert from "node:assert/strict";
import * as t from "@babel/types";
import {
  createBlock,
  checkIsBlockStatement,
  createEmptyBlock
} from "../src/index.mjs";

// Test 1: isBlockStatement returns true for valid BlockStatement AST nodes created via blockStatement builder
{
  const emptyBlock = createEmptyBlock();
  assert.equal(checkIsBlockStatement(emptyBlock), true);
  assert.equal(t.isBlockStatement(emptyBlock), true);

  const stmt = t.expressionStatement(t.identifier("x"));
  const blockWithStmt = createBlock([stmt]);
  assert.equal(checkIsBlockStatement(blockWithStmt), true);
  assert.equal(blockWithStmt.type, "BlockStatement");
  assert.equal(blockWithStmt.body.length, 1);
  assert.equal(blockWithStmt.body[0], stmt);
}

// Test 2: isBlockStatement returns false for non-BlockStatement AST nodes, primitives, and nullish values
{
  const idNode = t.identifier("foo");
  const numNode = t.numericLiteral(42);
  const exprStmt = t.expressionStatement(idNode);

  assert.equal(checkIsBlockStatement(idNode), false);
  assert.equal(checkIsBlockStatement(numNode), false);
  assert.equal(checkIsBlockStatement(exprStmt), false);
  assert.equal(checkIsBlockStatement(null), false);
  assert.equal(checkIsBlockStatement(undefined), false);
  assert.equal(checkIsBlockStatement("not-a-node"), false);
  assert.equal(checkIsBlockStatement(123), false);
  assert.equal(checkIsBlockStatement({ type: "Program" }), false);
  assert.equal(checkIsBlockStatement({}), false);
}

// Test 3: isBlockStatement supports property matching against node attributes such as directives and type
{
  const directives = [t.directive(t.directiveLiteral("use strict"))];
  const blockWithDirectives = t.blockStatement([], directives);

  assert.equal(checkIsBlockStatement(blockWithDirectives, { type: "BlockStatement" }), true);
  assert.equal(checkIsBlockStatement(blockWithDirectives, { type: "Program" }), false);
  assert.equal(checkIsBlockStatement(blockWithDirectives, { directives }), true);
  assert.equal(checkIsBlockStatement(blockWithDirectives, { directives: [] }), false);
}

// Test 4: isBlockStatement correctly distinguishes block statements from other statement types
{
  const ifStmt = t.ifStatement(t.booleanLiteral(true), createEmptyBlock());
  const returnStmt = t.returnStatement(null);

  assert.equal(t.isBlockStatement(ifStmt), false);
  assert.equal(t.isBlockStatement(returnStmt), false);
  assert.equal(t.isBlockStatement(ifStmt.consequent), true);
  assert.equal(t.isIfStatement(ifStmt), true);
  assert.equal(t.isReturnStatement(returnStmt), true);
}

console.log("All @babel/types.isBlockStatement contract tests passed successfully.");