CodeSampleX

サンプル

jest-mock 29.7.0: fn

検証済みサンプル — npm jest-mock 29.7.0: fn. node 22 · linux debian/x64 · docker で contract を実行し、成功しました: fn creates a mock function that defaults to returning…

sha256:c3118cb3f4faa866d15da3d2999b2e580e5c5b4bdc9b892fd57fe4b4cd66ce39

このネットワークが提供するのは一つだけです。ビルドされるサンプル。サンドボックスで実行し、署名済みの受領証を保管します。等級はつけず、何も保証しません — 同じコードがあなたの環境でビルドされるかは測定していません。 合格した契約受領証を提出した異なる署名鍵の数です。1 なら作者だけ、2 以上なら他の誰かもビルドしています。鍵は自己生成で背後に登録された身元がないため、数えているのは人ではなく鍵です。 MIT-0

実行証拠

宣言された環境と署名済みの実行を分けてあります。このサンプルが何をどこで実行したかをそのまま確認できます。

証拠の基準
署名済みコントラクト合格
検証レシート
1
ビルドした署名鍵
1
宣言された環境 node 22.23 linux 24 · ubuntu · glibc 2.39 x64 node 22.23 javascript npm 10

検証実行環境

環境 コントラクト ステージ 実行日
node 22 · linux debian/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22@sha256:8a34c4ab3ea2…		 2026-09-06

ケース

HOW
ゴール
verify jest-mock.fn in pkg:npm/jest-mock@29.7.0
パッケージ
シンボル
  • jest-mock.fn
環境
node 22.23.2
作成日
2026-09-06T07:53:28Z

コントラクト

  1. fn creates a mock function that defaults to returning undefined and tracks call count and arguments
  2. fn records mock.calls, mock.results with return type, and mock.contexts for each invocation
  3. mockReturnValue and mockReturnValueOnce configure synchronous return values with once taking precedence
  4. mockResolvedValue and mockResolvedValueOnce return promises resolving to the configured values
  5. mockRejectedValue and mockRejectedValueOnce return promises rejecting with the configured errors
  6. mockImplementation and mockImplementationOnce override mock execution behavior sequentially
  7. mockReturnThis binds the returned value to the execution this context
  8. mockClear clears recorded calls and results while preserving current mock implementation
  9. mockReset clears recorded calls and resets implementation to return undefined
  10. withImplementation temporarily overrides mock implementation for the duration of a callback

ファイル

  • PROMPT.md
  • csx.json
  • index.js
  • package-lock.json
  • package.json
  • spec.json
  • test/contract.js

ソースアーティファクトをダウンロード (tar.gz)

ソース

PROMPT.md
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 jest-mock.fn in pkg:npm/jest-mock@29.7.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/jest-mock@29.7.0
Demonstrate these symbols/APIs:
  - jest-mock.fn

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.
csx.json
{"case":{"caseId":"case:sha256:3e202a7070bf30aa087035d08a25b597461e31832c7801d94ca31210e7643435","contract":["fn creates a mock function that defaults to returning undefined and tracks call count and arguments","fn records mock.calls, mock.results with return type, and mock.contexts for each invocation","mockReturnValue and mockReturnValueOnce configure synchronous return values with once taking precedence","mockResolvedValue and mockResolvedValueOnce return promises resolving to the configured values","mockRejectedValue and mockRejectedValueOnce return promises rejecting with the configured errors","mockImplementation and mockImplementationOnce override mock execution behavior sequentially","mockReturnThis binds the returned value to the execution this context","mockClear clears recorded calls and results while preserving current mock implementation","mockReset clears recorded calls and resets implementation to return undefined","withImplementation temporarily overrides mock implementation for the duration of a callback"],"goal":"verify jest-mock.fn in pkg:npm/jest-mock@29.7.0","kind":"HOW","packages":["pkg:npm/jest-mock@29.7.0"],"schemaVersion":1,"symbols":["jest-mock.fn"]},"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/jest-mock@29.7.0"],"schemaVersion":1,"subject":"pkg:npm/jest-mock@29.7.0","symbols":["jest-mock.fn"],"verifierAdapter":"node-typescript@1"}
index.js
'use strict';

const jestMock = require('jest-mock');
const { fn } = jestMock;

/**
 * Creates a mock function with an optional implementation.
 * @param {Function} [implementation]
 * @returns {Function}
 */
function createMockFunction(implementation) {
  return fn(implementation);
}

/**
 * Creates an async mock function that resolves to the specified value.
 * @param {*} resolvedValue
 * @returns {Function}
 */
function createAsyncMock(resolvedValue) {
  const mock = fn();
  mock.mockResolvedValue(resolvedValue);
  return mock;
}

/**
 * Creates an async mock function that rejects with the specified reason.
 * @param {*} rejectionReason
 * @returns {Function}
 */
function createRejectingMock(rejectionReason) {
  const mock = fn();
  mock.mockRejectedValue(rejectionReason);
  return mock;
}

/**
 * Creates a mock function configured to return a sequence of values once,
 * then fall back to a default value.
 * @param {Array<*>} sequence
 * @param {*} [defaultValue]
 * @returns {Function}
 */
function createSequenceMock(sequence, defaultValue) {
  const mock = fn();
  if (defaultValue !== undefined) {
    mock.mockReturnValue(defaultValue);
  }
  for (const val of sequence) {
    mock.mockReturnValueOnce(val);
  }
  return mock;
}

/**
 * Creates a mock function that returns its `this` execution context.
 * @returns {Function}
 */
function createChainableMock() {
  const mock = fn();
  mock.mockReturnThis();
  return mock;
}

/**
 * Extracts metadata and call history from a mock function.
 * @param {Function} mockFn
 * @returns {object}
 */
function inspectMock(mockFn) {
  return {
    name: mockFn.getMockName(),
    callCount: mockFn.mock.calls.length,
    calls: [...mockFn.mock.calls],
    results: [...mockFn.mock.results],
    lastCall: mockFn.mock.lastCall
  };
}

module.exports = {
  fn,
  createMockFunction,
  createAsyncMock,
  createRejectingMock,
  createSequenceMock,
  createChainableMock,
  inspectMock
};
package-lock.json
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package.json
{
  "name": "sample-jest-mock-fn-verify",
  "version": "1.0.0",
  "private": true,
  "description": "verify jest-mock.fn in pkg:npm/jest-mock@29.7.0",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "jest-mock": "29.7.0"
  },
  "license": "MIT-0"
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify jest-mock.fn in pkg:npm/jest-mock@29.7.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/jest-mock@29.7.0"
  ],
  "symbols": [
    "jest-mock.fn"
  ]
}
test/contract.js
'use strict';

const assert = require('assert');
const {
  fn,
  createMockFunction,
  createAsyncMock,
  createRejectingMock,
  createSequenceMock,
  createChainableMock,
  inspectMock
} = require('../index.js');

function testDefaultMockBehavior() {
  const mock = fn();
  assert.strictEqual(mock.getMockName(), 'jest.fn()');

  const result = mock('firstArg', 42);
  assert.strictEqual(result, undefined, 'default mock must return undefined');
  assert.strictEqual(mock.mock.calls.length, 1, 'call count must be 1');
  assert.deepStrictEqual(mock.mock.calls[0], ['firstArg', 42]);
  assert.deepStrictEqual(mock.mock.lastCall, ['firstArg', 42]);
}

function testInvocationRecordsAndContext() {
  const contextObj = { scope: 'test-scope' };
  const mock = fn(function (factor) {
    return factor * 10;
  });

  const returnedVal = mock.call(contextObj, 5);
  assert.strictEqual(returnedVal, 50);
  assert.strictEqual(mock.mock.calls.length, 1);
  assert.deepStrictEqual(mock.mock.calls[0], [5]);
  assert.strictEqual(mock.mock.contexts[0], contextObj);
  assert.strictEqual(mock.mock.results.length, 1);
  assert.strictEqual(mock.mock.results[0].type, 'return');
  assert.strictEqual(mock.mock.results[0].value, 50);

  const errorMock = fn(() => {
    throw new Error('intentional failure');
  });

  assert.throws(() => errorMock(), /intentional failure/);
  assert.strictEqual(errorMock.mock.results[0].type, 'throw');
  assert.strictEqual(errorMock.mock.results[0].value.message, 'intentional failure');
}

function testReturnValuesConfiguration() {
  const mock = fn();
  mock.mockReturnValue('fallback');
  mock.mockReturnValueOnce('one');
  mock.mockReturnValueOnce('two');

  assert.strictEqual(mock(), 'one');
  assert.strictEqual(mock(), 'two');
  assert.strictEqual(mock(), 'fallback');
  assert.strictEqual(mock(), 'fallback');
}

async function testAsyncResolvedValues() {
  const mock = fn();
  mock.mockResolvedValue('default-async');
  mock.mockResolvedValueOnce('first-async');

  const res1 = await mock();
  assert.strictEqual(res1, 'first-async');

  const res2 = await mock();
  assert.strictEqual(res2, 'default-async');

  const helperMock = createAsyncMock('helper-async');
  const helperRes = await helperMock();
  assert.strictEqual(helperRes, 'helper-async');
}

async function testAsyncRejectedValues() {
  const mock = fn();
  mock.mockRejectedValue(new Error('default-async-error'));
  mock.mockRejectedValueOnce(new Error('first-async-error'));

  await assert.rejects(async () => {
    await mock();
  }, {
    name: 'Error',
    message: 'first-async-error'
  });

  await assert.rejects(async () => {
    await mock();
  }, {
    name: 'Error',
    message: 'default-async-error'
  });

  const rejectingHelper = createRejectingMock(new Error('helper-reject'));
  await assert.rejects(async () => {
    await rejectingHelper();
  }, {
    name: 'Error',
    message: 'helper-reject'
  });
}

function testImplementationChaining() {
  const mock = fn(() => 'base');
  mock.mockImplementationOnce(() => 'temp1');
  mock.mockImplementationOnce(() => 'temp2');
  mock.mockImplementation((x) => `custom-${x}`);

  assert.strictEqual(mock('a'), 'temp1');
  assert.strictEqual(mock('b'), 'temp2');
  assert.strictEqual(mock('c'), 'custom-c');
  assert.strictEqual(mock('d'), 'custom-d');
}

function testMockReturnThis() {
  const mock = fn();
  mock.mockReturnThis();

  const receiver = {
    action: mock
  };

  const chained = receiver.action();
  assert.strictEqual(chained, receiver, 'mockReturnThis must return the execution context');

  const helperChain = createChainableMock();
  const host = { chain: helperChain };
  assert.strictEqual(host.chain(), host);
}

function testMockClear() {
  const mock = fn((val) => val * 3);
  assert.strictEqual(mock(4), 12);
  assert.strictEqual(mock.mock.calls.length, 1);
  assert.strictEqual(mock.mock.results.length, 1);

  mock.mockClear();

  assert.strictEqual(mock.mock.calls.length, 0);
  assert.strictEqual(mock.mock.results.length, 0);
  assert.strictEqual(mock.mock.instances.length, 0);
  assert.strictEqual(mock.mock.contexts.length, 0);

  // Implementation remains intact
  assert.strictEqual(mock(5), 15);
  assert.strictEqual(mock.mock.calls.length, 1);
}

function testMockReset() {
  const mock = fn((val) => val * 3);
  assert.strictEqual(mock(4), 12);

  mock.mockReset();

  assert.strictEqual(mock.mock.calls.length, 0);
  assert.strictEqual(mock.mock.results.length, 0);
  // Implementation reset to empty function returning undefined
  assert.strictEqual(mock(5), undefined);
}

function testWithImplementation() {
  const mock = fn(() => 'original');
  let innerResult;

  mock.withImplementation(() => 'override', () => {
    innerResult = mock();
  });

  assert.strictEqual(innerResult, 'override');
  assert.strictEqual(mock(), 'original');
}

function testSequenceAndInspectHelpers() {
  const sequenceMock = createSequenceMock(['alpha', 'beta'], 'omega');
  assert.strictEqual(sequenceMock(), 'alpha');
  assert.strictEqual(sequenceMock(), 'beta');
  assert.strictEqual(sequenceMock(), 'omega');
  assert.strictEqual(sequenceMock(), 'omega');

  const customNamed = createMockFunction();
  customNamed.mockName('inspectedMock');
  customNamed('arg1', 'arg2');

  const stats = inspectMock(customNamed);
  assert.strictEqual(stats.name, 'inspectedMock');
  assert.strictEqual(stats.callCount, 1);
  assert.deepStrictEqual(stats.calls, [['arg1', 'arg2']]);
  assert.deepStrictEqual(stats.lastCall, ['arg1', 'arg2']);
  assert.strictEqual(stats.results[0].type, 'return');
}

async function runAll() {
  testDefaultMockBehavior();
  testInvocationRecordsAndContext();
  testReturnValuesConfiguration();
  await testAsyncResolvedValues();
  await testAsyncRejectedValues();
  testImplementationChaining();
  testMockReturnThis();
  testMockClear();
  testMockReset();
  testWithImplementation();
  testSequenceAndInspectHelpers();

  console.log('Contract tests passed successfully.');
}

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

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