jest-each 29.7.0: parameterized tests using jest-each table and template literal

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Goal: parameterized tests using jest-each table and template literal
Kind: HOW

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

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.

# jest-each Parameterized Testing Sample

This sample demonstrates how to write parameterized tests using `jest-each` with:
- 2D and 1D array tables and placeholder formatting (`%s`, `%i`, `%d`)
- Tagged template literal tables with column headings and `$variable` interpolation
- Custom test runner binding via `each.withGlobal` and `bind`

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{
  "name": "sample-jest-each",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "dependencies": {
    "jest-each": "29.7.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "parameterized tests using jest-each table and template literal",
  "kind": "HOW",
  "packages": [
    "pkg:npm/jest-each@29.7.0"
  ],
  "symbols": [
    "each"
  ]
}

import eachPkg, { bind } from 'jest-each';

const each = eachPkg.default || eachPkg;

/**
 * Runs parameterized tests against an array of test cases.
 *
 * @param {Array<Array<any>>} table - Table of test case input parameters.
 * @param {string} title - Test title template with placeholders (%s, %i, %d, %j, %o).
 * @param {Function} testFn - Test callback function.
 * @param {Object} [customGlobal] - Optional global test environment mock.
 */
export function runArrayTests(table, title, testFn, customGlobal) {
  const runner = customGlobal ? each.withGlobal(customGlobal) : each;
  return runner(table).test(title, testFn);
}

/**
 * Runs parameterized tests with tagged template literal table syntax.
 *
 * @param {TemplateStringsArray} strings - Template literal strings defining header and row delimiters.
 * @param {...any} expressions - Interpolated test values.
 * @returns {{ test: Function, describe: Function }}
 */
export function templateEach(strings, ...expressions) {
  return each(strings, ...expressions);
}

/**
 * Directly binds a custom test runner callback for parameterized execution.
 *
 * @param {Function} runner - Custom test runner (title, testFn) => void.
 * @param {Array<any>} table - Test cases table.
 * @param {string} title - Title template.
 * @param {Function} testFn - Test function.
 */
export function runWithCustomRunner(runner, table, title, testFn) {
  const boundTest = bind(runner)(table);
  return boundTest(title, testFn);
}

export { each, bind };

import assert from 'node:assert/strict';
import eachPkg, { bind } from 'jest-each';
import { runArrayTests, runWithCustomRunner } from '../src/index.mjs';

const each = eachPkg.default || eachPkg;

function createMockGlobal() {
  const recorded = [];

  const makeTestFn = (name) => {
    const fn = (title, testFn) => {
      recorded.push({ type: name, title, testFn });
    };
    fn.skip = (title, testFn) => recorded.push({ type: `${name}.skip`, title, testFn });
    fn.only = (title, testFn) => recorded.push({ type: `${name}.only`, title, testFn });
    const concurrent = (title, testFn) => recorded.push({ type: `${name}.concurrent`, title, testFn });
    concurrent.only = (title, testFn) => recorded.push({ type: `${name}.concurrent.only`, title, testFn });
    concurrent.skip = (title, testFn) => recorded.push({ type: `${name}.concurrent.skip`, title, testFn });
    fn.concurrent = concurrent;
    return fn;
  };

  const makeDescribeFn = (name) => {
    const fn = (title, suiteFn) => {
      recorded.push({ type: name, title, suiteFn });
    };
    fn.skip = (title, suiteFn) => recorded.push({ type: `${name}.skip`, title, suiteFn });
    fn.only = (title, suiteFn) => recorded.push({ type: `${name}.only`, title, suiteFn });
    return fn;
  };

  const g = {
    test: makeTestFn('test'),
    it: makeTestFn('it'),
    xit: (title, testFn) => recorded.push({ type: 'xit', title, testFn }),
    fit: (title, testFn) => recorded.push({ type: 'fit', title, testFn }),
    xtest: (title, testFn) => recorded.push({ type: 'xtest', title, testFn }),
    describe: makeDescribeFn('describe'),
    fdescribe: (title, suiteFn) => recorded.push({ type: 'fdescribe', title, suiteFn }),
    xdescribe: (title, suiteFn) => recorded.push({ type: 'xdescribe', title, suiteFn })
  };

  return { g, recorded };
}

// 1. Array table syntax with %i, %s and %d formatting via withGlobal
{
  const { g, recorded } = createMockGlobal();
  const customEach = each.withGlobal(g);

  customEach([
    [1, 2, 3],
    [2, 3, 5],
    [10, -5, 5]
  ]).test('adds %i + %i = %i', (a, b, expected) => {
    assert.equal(a + b, expected);
  });

  assert.equal(recorded.length, 3);
  assert.equal(recorded[0].title, 'adds 1 + 2 = 3');
  assert.equal(recorded[1].title, 'adds 2 + 3 = 5');
  assert.equal(recorded[2].title, 'adds 10 + -5 = 5');

  for (const item of recorded) {
    item.testFn();
  }
}

// 2. Tagged template literal syntax with object destructuring and $variable formatting
{
  const { g, recorded } = createMockGlobal();
  const customEach = each.withGlobal(g);

  customEach`
    a    | b    | expected
    ${2} | ${3} | ${6}
    ${4} | ${5} | ${20}
  `.test('multiplies $a * $b to get $expected', ({ a, b, expected }) => {
    assert.equal(a * b, expected);
  });

  assert.equal(recorded.length, 2);
  assert.equal(recorded[0].title, 'multiplies 2 * 3 to get 6');
  assert.equal(recorded[1].title, 'multiplies 4 * 5 to get 20');

  for (const item of recorded) {
    item.testFn();
  }
}

// 3. Direct bind API with 2D array and custom runner
{
  const recorded = [];
  const runner = (title, testFn) => {
    recorded.push({ title, testFn });
  };

  const eachTest = bind(runner)([
    ['hello', 5],
    ['world', 5],
    ['antigravity', 11]
  ]);

  eachTest('length of "%s" is %i', (str, len) => {
    assert.equal(str.length, len);
  });

  assert.equal(recorded.length, 3);
  assert.equal(recorded[0].title, 'length of "hello" is 5');
  assert.equal(recorded[1].title, 'length of "world" is 5');
  assert.equal(recorded[2].title, 'length of "antigravity" is 11');

  for (const item of recorded) {
    item.testFn();
  }
}

// 4. describe suite parameterization with withGlobal
{
  const { g, recorded } = createMockGlobal();
  const customEach = each.withGlobal(g);

  customEach([
    ['admin', true],
    ['guest', false]
  ]).describe('User role %s (isAdmin: %s)', (role, isAdmin) => {
    assert.equal(typeof role, 'string');
    assert.equal(typeof isAdmin, 'boolean');
  });

  assert.equal(recorded.length, 2);
  assert.equal(recorded[0].title, 'User role admin (isAdmin: true)');
  assert.equal(recorded[1].title, 'User role guest (isAdmin: false)');

  for (const item of recorded) {
    item.suiteFn();
  }
}

// 5. 1D Array syntax passes element directly as parameter
{
  const recorded = [];
  const runner = (title, testFn) => {
    recorded.push({ title, testFn });
  };

  const eachTest = bind(runner)(['alpha', 'beta', 'gamma']);
  eachTest('item: %s', (item) => {
    assert.equal(typeof item, 'string');
  });

  assert.equal(recorded.length, 3);
  assert.equal(recorded[0].title, 'item: alpha');
  assert.equal(recorded[1].title, 'item: beta');
  assert.equal(recorded[2].title, 'item: gamma');

  for (const item of recorded) {
    item.testFn();
  }
}

// 6. Validation: bind throws when called with non-array table
{
  const errors = [];
  const runner = (title, testFn) => {
    try {
      testFn();
    } catch (err) {
      errors.push(err);
    }
  };

  bind(runner)(12345)('invalid table type', () => {});
  assert.equal(errors.length, 1);
  assert.match(errors[0].message, /must be called with an Array or Tagged Template Literal/);
}

// 7. Validation: bind throws when called with empty array
{
  const errors = [];
  const runner = (title, testFn) => {
    try {
      testFn();
    } catch (err) {
      errors.push(err);
    }
  };

  bind(runner)([])('empty array', () => {});
  assert.equal(errors.length, 1);
  assert.match(errors[0].message, /called with an empty Array of table data/);
}

// 8. Validation: install throws when called with invalid data arguments
{
  const { g } = createMockGlobal();
  assert.throws(
    () => {
      each.withGlobal(g)(12345, 'extra-arg');
    },
    /must only be called with an Array or Tagged Template Literal/
  );
}

// 9. Helper wrapper functions verification
{
  const { g, recorded } = createMockGlobal();
  runArrayTests([[10, 20]], 'test %i %i', (a, b) => {
    assert.equal(a + b, 30);
  }, g);
  assert.equal(recorded.length, 1);
  assert.equal(recorded[0].title, 'test 10 20');
  recorded[0].testFn();

  const runnerItems = [];
  runWithCustomRunner((title, testFn) => {
    runnerItems.push({ title, testFn });
  }, [[1, 2]], 'sum %i %i', (x, y) => {
    assert.equal(x + y, 3);
  });
  assert.equal(runnerItems.length, 1);
  assert.equal(runnerItems[0].title, 'sum 1 2');
  runnerItems[0].testFn();
}

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