### Question:
Calculator { public double addition(double firstOperand, double secondOperand) { return firstOperand + secondOperand; }  double addition(double firstOperand, double secondOperand); double subtraction(double firstOperand, double secondOperand); double division(double firstOperand, double secondOperand); double multiplication(double firstOperand, double secondOperand);  }### Answer:
@Test public void addTwoNumbers() { double resultAdd = mCalculator.addition(1d, 1d); assertThat(resultAdd, is(equalTo(2d))); }
@Test public void addTwoNumbersNegative(){ double resultAdd = mCalculator.addition(-1d, 2d); assertThat(resultAdd, is(equalTo(1d))); }
@Test public void addTwoNumbersFloats(){ double resultAdd = mCalculator.addition(1.111f, 1.111d); assertThat(resultAdd, is(closeTo(2.222d, 0.01))); }