@Test public void addTwoNumbersNegative(){ double resultAdd = mCalculator.addition(-1d, 2d); assertThat(resultAdd, is(equalTo(1d))); }
public double addition(double firstOperand, double secondOperand) { return firstOperand + secondOperand; }
Calculator { public double addition(double firstOperand, double secondOperand) { return firstOperand + secondOperand; } }
Calculator { public double addition(double firstOperand, double secondOperand) { return firstOperand + secondOperand; }  }
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); }
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);  }