const {invertKeyValues} = require('./_30s.js');

test('invertKeyValues is a Function', () => {
  expect(invertKeyValues).toBeInstanceOf(Function);
});
test("invertKeyValues({ a: 1, b: 2, c: 1 }) returns { 1: [ 'a', 'c' ], 2: [ 'b' ] }", () => {
  expect(invertKeyValues({ a: 1, b: 2, c: 1 })).toEqual({ 1: ['a', 'c'], 2: ['b'] });
});
test("invertKeyValues({ a: 1, b: 2, c: 1 }, value => 'group' + value) returns { group1: [ 'a', 'c' ], group2: [ 'b' ] }", () => {
  expect(invertKeyValues({ a: 1, b: 2, c: 1 }, value => 'group' + value)).toEqual({
    group1: ['a', 'c'],
    group2: ['b']
  });
});