expect.js test tips

expectThrowError.js

function targetMethod(param) {
  if(param === null || param === undefined) {
    throw new Error('param is empty.');
  }
  
  if(typeof param !== 'string') {
    throw new Error('param must be a Number.');
  }
  
  console.log(param);
}

// closure
var result1 = function() {
  var _badParam = null;
  targetMethod(_badParam);
};
var result2 = function() {
  var _badParam = 'string';
  targetMethod(_badParam);
}

// throwError
expect(result1).to.throwError();

// Check the error message using a regex.
expect(result1).to.throwError(/param is empty/);
expect(result2).to.throwError(/param must be a Number./);