@babel/generator 7.29.7: CodeGenerator, generate

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/%40babel/generator@7.29.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/generator@7.29.7
Demonstrate these symbols/APIs:
  - CodeGenerator
  - generate

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:af9c27c91b3d91f3f6453dfb3789ee7f48715f1555e6099a07df30e8de2a3380","contract":["generate converts AST Program node containing variable declarations into formatted JavaScript code","generate formats FunctionDeclaration with parameters and binary expression return statement","generate produces minified code without redundant whitespace when minified option is enabled","generate generates source maps with version 3 mappings when sourceMaps option is enabled","generate controls comment emission via comments configuration option","generate formats code using CodeGenerator class with custom generator options","generate throws an Error when passed an unknown AST node type"],"goal":"verify pkg:npm/%40babel/generator@7.29.7","kind":"HOW","packages":["pkg:npm/%40babel/generator@7.29.7"],"schemaVersion":1,"symbols":["CodeGenerator","generate"]},"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/%40babel/generator@7.29.7"],"schemaVersion":1,"subject":"pkg:npm/%40babel/generator@7.29.7","symbols":["CodeGenerator","generate"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-babel-generator",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-babel-generator",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@babel/generator": "7.29.7"
      }
    },
    "node_modules/@babel/generator": {
      "version": "7.29.7",
      "resolved": "https://registry.npmjs.org/@babel/generator/-/generator-7.29.7.tgz",
      "integrity": "sha512-DkXD5OJQaAQIdZ1bt3UZdEnHAn9Imd3IVBdX03UFe+ony9Ojw5pzr9YVKGDY1jt+Gcn/FnGkNf8r+Vj5NOJWtQ==",
      "license": "MIT",
      "dependencies": {
        "@babel/parser": "^7.29.7",
        "@babel/types": "^7.29.7",
        "@jridgewell/gen-mapping": "^0.3.12",
        "@jridgewell/trace-mapping": "^0.3.28",
        "jsesc": "^3.0.2"
      },
      "engines": {
        "node": ">=6.9.0"
      }
    },
    "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/parser": {
      "version": "7.29.8",
      "resolved": "https://registry.npmjs.org/@babel/parser/-/parser-7.29.8.tgz",
      "integrity": "sha512-E8lTAYNB1KW+FH+VGJuZM1ioAx2E6oVlvQFRrf5P8ZZmsiJXYAD9vTFV7yyEURNzgh1dFqMZuO6tUwcARbqFCA==",
      "license": "MIT",
      "dependencies": {
        "@babel/types": "^7.29.8"
      },
      "bin": {
        "parser": "bin/babel-parser.js"
      },
      "engines": {
        "node": ">=6.0.0"
      }
    },
    "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"
      }
    },
    "node_modules/@jridgewell/gen-mapping": {
      "version": "0.3.13",
      "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.13.tgz",
      "integrity": "sha512-2kkt/7niJ6MgEPxF0bYdQ6etZaA+fQvDcLKckhy1yIQOzaoKjBBjSj63/aLVjYE3qhRt5dvM+uUyfCg6UKCBbA==",
      "license": "MIT",
      "dependencies": {
        "@jridgewell/sourcemap-codec": "^1.5.0",
        "@jridgewell/trace-mapping": "^0.3.24"
      }
    },
    "node_modules/@jridgewell/resolve-uri": {
      "version": "3.1.2",
      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.2.tgz",
      "integrity": "sha512-bRISgCIjP20/tbWSPWMEi54QVPRZExkuD9lJL+UIxUKtwVJA8wW1Trb1jMs1RFXo1CBTNZ/5hpC9QvmKWdopKw==",
      "license": "MIT",
      "engines": {
        "node": ">=6.0.0"
      }
    },
    "node_modules/@jridgewell/sourcemap-codec": {
      "version": "1.5.5",
      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
      "integrity": "sha512-cYQ9310grqxueWbl+WuIUIaiUaDcj7WOq5fVhEljNVgRfOUhY9fy2zTvfoqWsnebh8Sl70VScFbICvJnLKB0Og==",
      "license": "MIT"
    },
    "node_modules/@jridgewell/trace-mapping": {
      "version": "0.3.31",
      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.31.tgz",
      "integrity": "sha512-zzNR+SdQSDJzc8joaeP8QQoCQr8NuYx2dIIytl1QeBEZHJ9uW6hebsrYgbz8hJwUQao3TWCMtmfV8Nu1twOLAw==",
      "license": "MIT",
      "dependencies": {
        "@jridgewell/resolve-uri": "^3.1.0",
        "@jridgewell/sourcemap-codec": "^1.4.14"
      }
    },
    "node_modules/jsesc": {
      "version": "3.1.0",
      "resolved": "https://registry.npmjs.org/jsesc/-/jsesc-3.1.0.tgz",
      "integrity": "sha512-/sM3dO2FOzXjKQhJuo0Q173wf2KOo8t4I8vHy6lF9poUp7bKT0/NHE8fPX23PwfhnykfqnC2xRxOnVw5XuGIaA==",
      "license": "MIT",
      "bin": {
        "jsesc": "bin/jsesc"
      },
      "engines": {
        "node": ">=6"
      }
    }
  }
}

{
  "name": "sample-babel-generator",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "@babel/generator": "7.29.7"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40babel/generator@7.29.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/generator@7.29.7"
  ],
  "symbols": [
    "CodeGenerator",
    "generate"
  ]
}

import generatorPkg from "@babel/generator";

const generateFn = typeof generatorPkg.default === "function"
  ? generatorPkg.default
  : (generatorPkg.default?.default || generatorPkg.generate || generatorPkg);

export const CodeGenerator = generatorPkg.CodeGenerator;

export function generateCode(ast, options = {}) {
  return generateFn(ast, options);
}

export function generateMinified(ast) {
  return generateFn(ast, { minified: true });
}

export function generateWithSourceMap(ast, sourceFileName) {
  return generateFn(ast, {
    sourceMaps: true,
    sourceFileName
  });
}

export function generateWithCommentsOption(ast, comments) {
  return generateFn(ast, { comments });
}

export function generateWithCustomGenerator(ast, options = {}) {
  const customGenerator = new CodeGenerator(ast, options);
  return customGenerator.generate();
}

import assert from "node:assert/strict";
import {
  CodeGenerator,
  generateCode,
  generateMinified,
  generateWithSourceMap,
  generateWithCommentsOption,
  generateWithCustomGenerator
} from "../src/index.mjs";

// 1. generate converts AST Program node containing variable declarations into formatted JavaScript code
{
  const ast = {
    type: "Program",
    body: [
      {
        type: "VariableDeclaration",
        kind: "const",
        declarations: [
          {
            type: "VariableDeclarator",
            id: { type: "Identifier", name: "greeting" },
            init: { type: "StringLiteral", value: "hello" }
          }
        ]
      }
    ]
  };
  const result = generateCode(ast);
  assert.equal(typeof result.code, "string");
  assert.equal(result.code, 'const greeting = "hello";');
}

// 2. generate formats FunctionDeclaration with parameters and binary expression return statement
{
  const ast = {
    type: "FunctionDeclaration",
    id: { type: "Identifier", name: "multiply" },
    params: [
      { type: "Identifier", name: "a" },
      { type: "Identifier", name: "b" }
    ],
    body: {
      type: "BlockStatement",
      body: [
        {
          type: "ReturnStatement",
          argument: {
            type: "BinaryExpression",
            operator: "*",
            left: { type: "Identifier", name: "a" },
            right: { type: "Identifier", name: "b" }
          }
        }
      ]
    }
  };
  const result = generateCode(ast);
  assert.match(result.code, /function multiply\(a, b\)/);
  assert.match(result.code, /return a \* b;/);
}

// 3. generate produces minified code without redundant whitespace when minified option is enabled
{
  const ast = {
    type: "FunctionDeclaration",
    id: { type: "Identifier", name: "fn" },
    params: [],
    body: {
      type: "BlockStatement",
      body: [
        {
          type: "ReturnStatement",
          argument: { type: "NumericLiteral", value: 1 }
        }
      ]
    }
  };
  const result = generateMinified(ast);
  assert.equal(result.code, "function fn(){return 1}");
}

// 4. generate generates source maps with version 3 mappings when sourceMaps option is enabled
{
  const ast = {
    type: "Identifier",
    name: "myVar",
    loc: {
      start: { line: 1, column: 0 },
      end: { line: 1, column: 5 },
      filename: "test.js"
    }
  };
  const result = generateWithSourceMap(ast, "test.js");
  assert.ok(result.map, "Expected sourcemap object to be present");
  assert.equal(result.map.version, 3);
}

// 5. generate controls comment emission via comments configuration option
{
  const ast = {
    type: "ExpressionStatement",
    expression: { type: "Identifier", name: "x" },
    leadingComments: [
      {
        type: "CommentLine",
        value: " important comment"
      }
    ]
  };
  const withComments = generateWithCommentsOption(ast, true);
  assert.match(withComments.code, /\/\/ important comment/);

  const withoutComments = generateWithCommentsOption(ast, false);
  assert.equal(withoutComments.code.includes("important comment"), false);
}

// 6. generate formats code using CodeGenerator class with custom generator options
{
  const ast = {
    type: "ReturnStatement",
    argument: { type: "BooleanLiteral", value: true }
  };
  const result = generateWithCustomGenerator(ast, { concise: true });
  assert.equal(result.code, "return true;");
}

// 7. generate throws an Error when passed an unknown AST node type
{
  assert.throws(
    () => {
      generateCode({ type: "UnknownCustomInvalidNodeType" });
    },
    Error
  );
}

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