funset.js

const test = require('tape');

const emptyContainer = () => null;
const checkWith = el1 => el2 => el1 === el2 ? el2 : null;
const inContainer = ( containingFn, el ) => containingFn( el ) === el;
const inEither = ( a, b ) => el => inContainer( a, el ) ? el : b( el );
const inAny = ( ...containingFns ) => containingFns.reduce( inEither, checkWith( null ) );
const inBoth = ( a, b ) => el => inContainer( a, el ) &&  inContainer( b, el ) ? el : null;
const inAll = ( ...containingFns ) => containingFns.reduce( inBoth, checkWith );

// test data
const randEls = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const fnSet = checkWith('success');
const fnSet1 = checkWith(true);
const fnSet2 = checkWith(false);
const fnSet3 = checkWith('test1');
const fnSet4 = checkWith('test2');
const fnSet5 = checkWith('test1');
const fnSet6 = checkWith(false);
const uSet = inEither(fnSet3, fnSet4);
const uSet1 = inEither(fnSet1, fnSet2);
const uSet2 = inEither(fnSet2, fnSet1);
const uaSet = inAny( ...randEls.map(checkWith) );
const iSet = inBoth(fnSet3, fnSet5);
const iSet1 = inBoth(fnSet3, fnSet4);
const iSet2 = inBoth(fnSet1, fnSet2);
const iSet3 = inBoth(fnSet2, fnSet1);
const iSet4 = inBoth(fnSet2, fnSet6);
const iSet5 = inBoth(fnSet6, fnSet2);

// assemble the test data
const testData = [].concat(
  {
    title: 'Empty Container',
    result:  [
      emptyContainer(1),
      emptyContainer(false),
      emptyContainer('test'),
    ],
    expect1: [null, null, null],
  },
  {
    title: 'Check With',
    result:  [
      fnSet(1),
      fnSet(false),
      fnSet('test'),
    ],
    expect1: [null, null, null],
  },
  {
    title: 'In Container',
    result:  [
      inContainer(fnSet, 'success'),
      inContainer(fnSet2, false),
      inContainer(fnSet, 'fail'),
      inContainer(fnSet2, true),
    ],
    expect1: [true, true, false, false],
  },
  {
    title: 'In Either',
    result:  [
      uSet(1),
      uSet(false),
      uSet('test'),
      uSet('test1'),
      uSet('test2'),
      uSet1(false),
      uSet2(false),
    ],
    expect1: [null, null, null, 'test1', 'test2', false, false],
  },
  {
    title: 'In Any',
    result:  [
      uaSet(1),
      uaSet(3),
      uaSet(7),
      uaSet(10),
      uaSet(false),
      uaSet('test'),
      uaSet('test1'),
      uaSet('test2'),
    ],
    expect1: [1, 3, 7, 10, null, null, null, null],
  },
  {
    title: 'In Both - Overlap',
    result:  [
      iSet(1),
      iSet(false),
      iSet('test'),
      iSet('test1'),
    ],
    expect1: [null, null, null, 'test1'],
  },
  {
    title: 'In Both - No Overlap',
    result:  [
      iSet1(1),
      iSet1(false),
      iSet1('test'),
      iSet1('test1'),
      iSet1('test2'),
    ],
    expect1: [null, null, null, null, null],
  },
  {
    title: 'In Both - True/False Checks',
    result:  [
      iSet2(false),
      iSet3(false),
      iSet4(false),
      iSet5(false),
    ],
    expect1: [null, null, false, false],
  },
);


// run the tests
test('FSet Tests', function (assert) {
  assert.plan(testData.length);
  testData.forEach(function (testCase) {
    assert.deepEqual(testCase.result, testCase.expect1, testCase.title);
  });
});