@babel/types 7.29.8: catchClause

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.catchClause 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.catchClause
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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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  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
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      }
    },
    "node_modules/@babel/helper-string-parser": {
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      "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"
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    },
    "node_modules/@babel/helper-validator-identifier": {
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      "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"
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    },
    "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-catch-clause",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "@babel/types": "7.29.8"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @babel/types.catchClause in pkg:npm/%40babel/types@7.29.8",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/types@7.29.8"
  ],
  "symbols": [
    "@babel/types.catchClause"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
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    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

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

export function createCatchClause(param, bodyStatements = []) {
  const body = Array.isArray(bodyStatements)
    ? t.blockStatement(bodyStatements)
    : bodyStatements;
  return t.catchClause(param, body);
}

export function createOptionalCatchClause(bodyStatements = []) {
  const body = Array.isArray(bodyStatements)
    ? t.blockStatement(bodyStatements)
    : bodyStatements;
  return t.catchClause(null, body);
}

export function createDestructuredCatchClause(properties, bodyStatements = []) {
  const body = Array.isArray(bodyStatements)
    ? t.blockStatement(bodyStatements)
    : bodyStatements;
  const param = t.objectPattern(
    properties.map((prop) =>
      typeof prop === "string"
        ? t.objectProperty(t.identifier(prop), t.identifier(prop), false, true)
        : prop
    )
  );
  return t.catchClause(param, body);
}

export function isValidCatchClause(node, opts) {
  return t.isCatchClause(node, opts);
}

export function validateCatchClause(node, opts) {
  t.assertCatchClause(node, opts);
  return true;
}

export function wrapInTryCatch(tryStatements, catchClause, finallyStatements = null) {
  const tryBlock = t.blockStatement(tryStatements);
  const finallyBlock = finallyStatements ? t.blockStatement(finallyStatements) : null;
  return t.tryStatement(tryBlock, catchClause, finallyBlock);
}

import assert from "node:assert/strict";
import * as t from "@babel/types";
import {
  createCatchClause,
  createOptionalCatchClause,
  createDestructuredCatchClause,
  isValidCatchClause,
  validateCatchClause,
  wrapInTryCatch
} from "../src/index.mjs";

// Test 1: catchClause creates a CatchClause AST node with a parameter identifier and a block statement body
{
  const param = t.identifier("error");
  const logStatement = t.expressionStatement(
    t.callExpression(
      t.memberExpression(t.identifier("console"), t.identifier("error")),
      [t.identifier("error")]
    )
  );
  const clause = createCatchClause(param, [logStatement]);

  assert.equal(clause.type, "CatchClause");
  assert.equal(clause.param.type, "Identifier");
  assert.equal(clause.param.name, "error");
  assert.equal(clause.body.type, "BlockStatement");
  assert.equal(clause.body.body.length, 1);

  assert.equal(isValidCatchClause(clause), true);
  assert.equal(validateCatchClause(clause), true);
}

// Test 2: catchClause creates an optional catch binding node when parameter is null or omitted
{
  const clause = createOptionalCatchClause([]);

  assert.equal(clause.type, "CatchClause");
  assert.equal(clause.param, null);
  assert.equal(clause.body.type, "BlockStatement");
  assert.equal(clause.body.body.length, 0);

  assert.equal(isValidCatchClause(clause), true);
  assert.equal(isValidCatchClause(clause, { param: null }), true);
  assert.equal(validateCatchClause(clause), true);
}

// Test 3: catchClause creates a catch clause with pattern-based catch parameter such as ObjectPattern
{
  const clause = createDestructuredCatchClause(["message", "code"]);

  assert.equal(clause.type, "CatchClause");
  assert.equal(clause.param.type, "ObjectPattern");
  assert.equal(clause.param.properties.length, 2);
  assert.equal(clause.param.properties[0].key.name, "message");
  assert.equal(clause.param.properties[1].key.name, "code");

  assert.equal(isValidCatchClause(clause), true);
  assert.equal(validateCatchClause(clause), true);
}

// Test 4: isCatchClause returns true for valid CatchClause nodes and false for non-CatchClause nodes with optional property matching
{
  const clause = t.catchClause(t.identifier("err"), t.blockStatement([]));
  const numNode = t.numericLiteral(100);
  const blockNode = t.blockStatement([]);

  assert.equal(isValidCatchClause(clause), true);
  assert.equal(isValidCatchClause(clause, { param: clause.param }), true);
  assert.equal(isValidCatchClause(numNode), false);
  assert.equal(isValidCatchClause(blockNode), false);
  assert.equal(isValidCatchClause(null), false);
  assert.equal(isValidCatchClause(undefined), false);
}

// Test 5: assertCatchClause validates CatchClause AST nodes and throws an error on invalid or mismatched nodes
{
  const clause = t.catchClause(t.identifier("err"), t.blockStatement([]));

  assert.doesNotThrow(() => {
    t.assertCatchClause(clause);
  });

  assert.throws(() => {
    t.assertCatchClause(t.identifier("err"));
  });

  assert.throws(() => {
    t.assertCatchClause(null);
  });

  assert.throws(() => {
    t.assertCatchClause({});
  });

  assert.throws(() => {
    t.assertCatchClause(clause, { param: t.identifier("other") });
  });
}

// Test 6: CatchClause integrates as the handler node within a TryStatement AST construct
{
  const tryBody = [
    t.expressionStatement(
      t.callExpression(t.identifier("performOperation"), [])
    )
  ];
  const catchHandler = createCatchClause(t.identifier("err"), [
    t.expressionStatement(t.identifier("handleError"))
  ]);
  const finallyBody = [
    t.expressionStatement(t.identifier("cleanup"))
  ];

  const tryStmt = wrapInTryCatch(tryBody, catchHandler, finallyBody);

  assert.equal(tryStmt.type, "TryStatement");
  assert.equal(tryStmt.block.type, "BlockStatement");
  assert.equal(tryStmt.handler, catchHandler);
  assert.equal(tryStmt.finalizer.type, "BlockStatement");
  assert.equal(t.isTryStatement(tryStmt), true);
}

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