string.js

// Take string and get words as an array. Valid split characters are `,` `.` `\s` `/` `\n`
// words :: String -> [String]
export const words = str =>
    (str ? str.split(/[\s\n.,/]+/) : []) // split on whitespace
        .filter(Boolean);

string.spec.js

describe('words', () => {
        it('returns empty for empty', () => {
            expect(words('')).to.eql([]);
        });
        it('turns space separated words into array', () => {
            expect(words(`I told you`)).to.eql(['I', 'told', 'you']);
        });
        it('splits on path-like separators', () => {
            expect(words(`I.told/you`)).to.eql(['I', 'told', 'you']);
        });
        it('splits list-like separators', () => {
            expect(words(`I, told,you`)).to.eql(['I', 'told', 'you']);
        });
        it('ignores extra whitespace', () => {
            expect(words(`I told    you `)).to.eql(['I', 'told', 'you']);
        });
        it('allows new lines', () => {
            expect(words(`
        a
  bunch
      of
  stuff
      `)).to.eql(['a', 'bunch', 'of', 'stuff']);
        });
        it('ignores extra whitespace', () => {
            expect(words(`interpolation ${'still'}-works well`)).to.eql(
                ['interpolation', 'still-works', 'well']
            );
        });
    });

You know how I would test this? Using data driven snapshots! https://github.com/bahmutov/snap-shot-it#data-driven-testing

it('works', () => {
  snapshot(words, '', 'I told you', 'I.told/you', ...)
})