Google App Scripts Test Runner - Lightweight test utilty for GAS projects

First install UnderscoreGS GAS library. Then either copy contents of Test.gs file into your project or into a new GAS library to be imported into your project.

1. First write the unit test function which is any function that begins with "test"

// Test functions should return true for a pass or false for a fail.
function testSquare() {
  const input = 10
  const expectedOutput = 100
  const actualOutput = square(input)
  return expectedOutput === actualOutput
}

2. Write the function.

function square(input) {
  return input * input  
}

3. Execute runTests()