tinyspy 4.0.4: spy on object methods and getters setters with tinyspy spyOn and restore

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: spy on object methods and getters setters with tinyspy spyOn and restore
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/tinyspy@4.0.4
Demonstrate these symbols/APIs:
  - restoreAll
  - spyOn

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:c1256c70f77005ed11291b28a6d2b7ae75af9a78bc79c32f5f7f27250743835b","contract":["spyOn replaces an object method, records calls and return values, and executes the original method by default","spyOn supports custom mock functions and allows updating implementations with willCall","spyOn getter and setter traps property accesses and modifications","spy.restore restores the original method on the target object","restoreAll resets all active method and getter setter spies simultaneously"],"goal":"spy on object methods and getters setters with tinyspy spyOn and restore","kind":"HOW","packages":["pkg:npm/tinyspy@4.0.4"],"schemaVersion":1,"symbols":["restoreAll","spyOn"]},"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/tinyspy@4.0.4"],"schemaVersion":1,"subject":"pkg:npm/tinyspy@4.0.4","symbols":["restoreAll","spyOn"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-tinyspy-spyon",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-tinyspy-spyon",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "tinyspy": "4.0.4"
      }
    },
    "node_modules/tinyspy": {
      "version": "4.0.4",
      "resolved": "https://registry.npmjs.org/tinyspy/-/tinyspy-4.0.4.tgz",
      "integrity": "sha512-azl+t0z7pw/z958Gy9svOTuzqIk6xq+NSheJzn5MMWtWTFywIacg2wUlzKFGtt3cthx0r2SxMK0yzJOR0IES7Q==",
      "license": "MIT",
      "engines": {
        "node": ">=14.0.0"
      }
    }
  }
}

{
  "name": "sample-tinyspy-spyon",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "description": "Clean-room verification for spyOn and restoreAll in tinyspy@4.0.4",
  "main": "test/contract.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "tinyspy": "4.0.4"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "spy on object methods and getters setters with tinyspy spyOn and restore",
  "kind": "HOW",
  "packages": [
    "pkg:npm/tinyspy@4.0.4"
  ],
  "symbols": [
    "restoreAll",
    "spyOn"
  ]
}

import assert from "node:assert";
import { spyOn, restoreAll } from "tinyspy";

async function runContract() {
  // 1. Spying on an object method
  const calculator = {
    multiplier: 2,
    multiply(a, b) {
      return a * b * this.multiplier;
    },
    add(a, b) {
      return a + b;
    },
  };

  const multiplySpy = spyOn(calculator, "multiply");

  assert.strictEqual(multiplySpy.called, false, "multiplySpy.called should initially be false");
  assert.strictEqual(multiplySpy.callCount, 0, "multiplySpy.callCount should initially be 0");
  assert.deepStrictEqual(multiplySpy.calls, [], "multiplySpy.calls should initially be empty");

  const res1 = calculator.multiply(3, 4);
  assert.strictEqual(res1, 24, "calculator.multiply should execute original implementation with bound context");
  assert.strictEqual(multiplySpy.called, true, "multiplySpy.called should be true after call");
  assert.strictEqual(multiplySpy.callCount, 1, "multiplySpy.callCount should be 1");
  assert.deepStrictEqual(multiplySpy.calls, [[3, 4]], "multiplySpy.calls should record passed arguments");
  assert.deepStrictEqual(multiplySpy.returns, [24], "multiplySpy.returns should record return values");

  // 2. Custom mock implementation and willCall
  const addSpy = spyOn(calculator, "add", (a, b) => (a + b) * 10);
  const addRes1 = calculator.add(2, 3);
  assert.strictEqual(addRes1, 50, "calculator.add should execute custom mock implementation");
  assert.strictEqual(addSpy.callCount, 1, "addSpy.callCount should be 1");

  addSpy.willCall((a, b) => a - b);
  const addRes2 = calculator.add(10, 4);
  assert.strictEqual(addRes2, 6, "addSpy should use updated implementation from willCall");
  assert.strictEqual(addSpy.callCount, 2, "addSpy.callCount should be 2");

  // 3. Getter and setter spying on separate properties
  let readValue = "initial";
  let writtenValue = "";
  const container = {
    get item() {
      return readValue;
    },
    set itemSink(v) {
      writtenValue = v;
    },
  };

  const getSpy = spyOn(container, { getter: "item" });
  const setSpy = spyOn(container, { setter: "itemSink" });

  const retrieved = container.item;
  assert.strictEqual(retrieved, "initial", "getter should return current value");
  assert.strictEqual(getSpy.called, true, "getSpy.called should be true");
  assert.strictEqual(getSpy.callCount, 1, "getSpy.callCount should be 1");

  container.itemSink = "updated";
  assert.strictEqual(writtenValue, "updated", "setter should update state");
  assert.strictEqual(setSpy.called, true, "setSpy.called should be true");
  assert.strictEqual(setSpy.callCount, 1, "setSpy.callCount should be 1");
  assert.deepStrictEqual(setSpy.calls, [["updated"]], "setSpy.calls should record assigned value");

  // 4. Individual spy.restore() restores original behavior
  addSpy.restore();
  const directAddRes = calculator.add(2, 3);
  assert.strictEqual(directAddRes, 5, "restored method should execute original un-spied function");
  assert.strictEqual(addSpy.callCount, 2, "addSpy.callCount should not increment after restore");

  // 5. restoreAll() resets all active spies
  restoreAll();
  const directMultiplyRes = calculator.multiply(2, 5);
  assert.strictEqual(directMultiplyRes, 20, "calculator.multiply should be restored by restoreAll");
  assert.strictEqual(multiplySpy.callCount, 1, "multiplySpy.callCount should not increment after restoreAll");

  const unspiedItem = container.item;
  assert.strictEqual(unspiedItem, "initial", "container.item getter should work unspied");
  assert.strictEqual(getSpy.callCount, 1, "getSpy.callCount should not increment after restoreAll");

  container.itemSink = "final";
  assert.strictEqual(writtenValue, "final", "container.itemSink setter should work unspied");
  assert.strictEqual(setSpy.callCount, 1, "setSpy.callCount should not increment after restoreAll");

  console.log("Contract assertions verified successfully.");
}

runContract().catch((err) => {
  console.error("Contract test failed:", err);
  process.exit(1);
});