[Jest - How to Parameterized Tests and Describes] #Jest #JavaScript

example_parameterized_jest_describe.spec.js

const not = val => !val;
// How to parameterize describe in jest
describe("index", () => {
  describe.each([
      ['boolean', true, false],
      ['boolean', false, true],
      ['number', 0, true],
      ['number', 1, false],
      ['number', 999, false],
      ['number', -1, false],
      ['number', -999, false],
  ])('#not', (type, subject, expectedOutcome) => {
      test(`When parameter type of '${type}' with value of '${subject}' expected out is '${expectedOutcome}'`,  () => {
          expect(not(subject)).toEqual(expectedOutcome)
      });
  })
});

example_parameterized_jest_test.spec.js

const not = val => !val;
// How to parameterize tests in jest
describe("index", () => {
    describe('#not',() => {
        test.each([
            ['boolean', true, false],
            ['boolean', false, true],
            ['number', 0, true],
            ['number', 1, false],
            ['number', 999, false],
            ['number', -1, false],
            ['number', -999, false],
        ])(`When parameter type of '%s' with value of '%s' expected out is '%s'`, (type, subject, expectedOutcome) => {
            expect(not(subject)).toEqual(expectedOutcome);
        })
    }); 
});