JAVASCRIPT

test each jest

test.each([
  {a: 1, b: 1, expected: 2},
  {a: 1, b: 2, expected: 3},
  {a: 2, b: 1, expected: 3},
])('.add($a, $b)', ({a, b, expected}) => {
  expect(a + b).toBe(expected);
});

testing jest

const cal = require('../index');

test('adds 1 + 2 to equal 3', () => {
  expect(cal.sum(1, 2)).toBe(3);
  expect(cal.sum(1, 2)).not.toBe(4);
  expect(cal.sum(1, 2)).toBeGreaterThan(2);
  expect(cal.sum(1, 2)).toBeLessThan(4);
  expect(cal.sum(1, 2)).toBeCloseTo(3);
  // Testing datatype
  expect(typeof cal.sum(1, 2)).toBe("number");
});

testing with jest

npm i jest --save -dev
-> In Package.json change the Script object(watchAll - jest will run auto)
"test" : "jest --watchAll"
-> test file should be named such way that re used by jest can recognize it
like filename.<test> or <spec> or skip it.js
Ex: sum.test.js or sum.spec.js or sum.js
-> require the target for testing file in this test file then enjoy testing.
-> visit jestWebsite-> Docs.