Unit Tests

A unit test is an automated software test that checks whether a single aspect or function in some software is working as expected. For example, a calculator application might be split up into functions that deal with the Graphical User Interface (GUI) of the application and another set of functions responsible for each type of mathematical calculation.

In such a calculator, unit tests might be set up to ensure that each mathematical function works as expected. This setup allows us to quickly find any inconsistent results or broken functions caused by any changes. As an example, such a calculator's test file might include the following:

test('Check that 5 plus 7 is 12', () => {
  expect(math.add(5, 7)).toBe(12);
});
test('Check that 10 minus 3 is 7', () => {
  expect(math.subtract(10, 3)).toBe(7);
});
test('Check that 5 multiplied by 3 is 15', () => {
  expect(math.multiply(5, 3).toBe(15);
});
test('Check that 100 divided...