public void Gcd_Null_ThrowsArgumentNullException()
 {
     Assert.Throws <ArgumentNullException>(() => NumberExtensions.Gcd(null));
 }
 public int Gcd_3number_Result(int a, int b, int c)
 {
     return(NumberExtensions.Gcd(a, b, c));
 }
 public int Gcd_Args_Result(int[] a)
 {
     return(NumberExtensions.Gcd(a));
 }
 public int Gcd_2number_Result(int a, int b)
 {
     return(NumberExtensions.Gcd(a, b));
 }