neo-async 2.6.2: async.waterfall

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 async.waterfall in pkg:npm/neo-async@2.6.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/neo-async@2.6.2
Demonstrate these symbols/APIs:
  - async.waterfall
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.

{"case":{"caseId":"case:sha256:06342cba9a39036839714bb7295c3113adef703dd2b3e33af93406a7c75ca146","constraints":{"executionContext":"node"},"contract":["assert async.waterfall passes multiple results from one task to the next in series","assert async.waterfall halts execution and invokes final callback on error","assert async.waterfall handles empty task array by invoking callback with no error","assert async.waterfall maintains execution order with asynchronous callback dispatch","assert async.waterfall executes task sequence without final callback"],"goal":"verify async.waterfall in pkg:npm/neo-async@2.6.2","kind":"HOW","packages":["pkg:npm/neo-async@2.6.2"],"schemaVersion":1,"symbols":["async.waterfall"]},"contractCommand":["node","test/contract.js"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/neo-async@2.6.2"],"schemaVersion":1,"subject":"pkg:npm/neo-async@2.6.2","symbols":["async.waterfall"],"verifierAdapter":"node-typescript@1"}

const async = require('neo-async');

function runWaterfall(tasks, callback) {
  return async.waterfall(tasks, callback);
}

module.exports = {
  runWaterfall,
  waterfall: async.waterfall,
};

{
  "name": "sample-neo-async-waterfall",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-neo-async-waterfall",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "neo-async": "2.6.2"
      }
    },
    "node_modules/neo-async": {
      "version": "2.6.2",
      "resolved": "https://registry.npmjs.org/neo-async/-/neo-async-2.6.2.tgz",
      "integrity": "sha512-Yd3UES5mWCSqR+qNT93S3UoYUkqAZ9lLg8a7g9rimsWmYGK8cVToA4/sF3RrshdyV3sAGMXVUmpMYOw+dLpOuw==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-neo-async-waterfall",
  "version": "1.0.0",
  "description": "Demonstrate async.waterfall series execution in neo-async",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "license": "MIT-0",
  "dependencies": {
    "neo-async": "2.6.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify async.waterfall in pkg:npm/neo-async@2.6.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/neo-async@2.6.2"
  ],
  "symbols": [
    "async.waterfall"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

const assert = require('assert');
const { runWaterfall, waterfall } = require('../index');

function runAllTests() {
  const tests = [
    // 1. Pass multiple results from one task to the next in series
    function testWaterfallResultPassing(done) {
      const trace = [];
      runWaterfall(
        [
          function (cb) {
            trace.push('step1');
            cb(null, 'foo', 'bar');
          },
          function (arg1, arg2, cb) {
            trace.push('step2');
            assert.strictEqual(arg1, 'foo');
            assert.strictEqual(arg2, 'bar');
            cb(null, `${arg1}-${arg2}-baz`);
          },
        ],
        function (err, result) {
          assert.strictEqual(err, null);
          assert.strictEqual(result, 'foo-bar-baz');
          assert.deepStrictEqual(trace, ['step1', 'step2']);
          done();
        }
      );
    },

    // 2. Halt execution and invoke final callback on error
    function testWaterfallHaltsOnError(done) {
      const trace = [];
      const expectedErr = new Error('simulated failure');
      runWaterfall(
        [
          function (cb) {
            trace.push('step1');
            cb(null, 42);
          },
          function (val, cb) {
            trace.push('step2');
            cb(expectedErr);
          },
          function (val, cb) {
            trace.push('step3-should-not-run');
            cb(null, 100);
          },
        ],
        function (err, result) {
          assert.strictEqual(err, expectedErr);
          assert.strictEqual(result, undefined);
          assert.deepStrictEqual(trace, ['step1', 'step2']);
          done();
        }
      );
    },

    // 3. Handle empty task array by invoking callback with no error
    function testEmptyTaskArray(done) {
      runWaterfall([], function (err, result) {
        assert.strictEqual(err, null);
        assert.strictEqual(result, undefined);
        done();
      });
    },

    // 4. Maintain execution order with asynchronous callback dispatch
    function testAsyncDispatchOrder(done) {
      const order = [];
      runWaterfall(
        [
          function (cb) {
            setImmediate(() => {
              order.push('first');
              cb(null, 1);
            });
          },
          function (val, cb) {
            setTimeout(() => {
              order.push('second');
              cb(null, val + 1);
            }, 10);
          },
          function (val, cb) {
            setImmediate(() => {
              order.push('third');
              cb(null, val * 10);
            });
          },
        ],
        function (err, result) {
          assert.strictEqual(err, null);
          assert.strictEqual(result, 20);
          assert.deepStrictEqual(order, ['first', 'second', 'third']);
          done();
        }
      );
    },

    // 5. Execute task sequence without final callback
    function testWithoutFinalCallback(done) {
      let executed = false;
      waterfall([
        function (cb) {
          executed = true;
          cb(null, 'ok');
        },
      ]);
      assert.strictEqual(executed, true);
      done();
    },
  ];

  let index = 0;
  function next() {
    if (index >= tests.length) {
      console.log('All contract tests passed successfully.');
      return;
    }
    const currentTest = tests[index++];
    currentTest(() => {
      next();
    });
  }

  next();
}

runAllTests();