using NUnit.Framework ;
using Mono.Math ;

[ TestFixture ]
public class Factorial_BigInteger_Test {
  class DataPair {
    public ulong i ;
    public BigInteger expected ;
    public DataPair ( ulong i , BigInteger expected ) { this.i = i ; this.expected = expected ; }
  } ;
  private DataPair[] data = {
    new DataPair ( 0 , new BigInteger ( 1 ) ) ,
    new DataPair ( 1 , new BigInteger ( 1 ) ) ,
    new DataPair ( 2 , new BigInteger ( 2 ) ) ,
    new DataPair ( 3 , new BigInteger ( 6 ) ) ,
    new DataPair ( 4 , new BigInteger ( 24 ) ) ,
    new DataPair ( 5 , new BigInteger ( 120 ) ) ,
    new DataPair ( 6 , new BigInteger ( 720 ) ) ,
    new DataPair ( 7 , new BigInteger ( 5040 ) ) ,
    new DataPair ( 8 , new BigInteger ( 40320 ) ) ,
    new DataPair ( 9 , new BigInteger ( 362880 ) ) ,
    new DataPair ( 10 , new BigInteger ( 3628800 ) ) ,
    new DataPair ( 11 , new BigInteger ( 39916800 ) ) ,
    new DataPair ( 12 , new BigInteger ( 479001600 ) ) ,
    new DataPair ( 13 , new BigInteger ( 6227020800 ) ) ,
    new DataPair ( 14 , new BigInteger ( 87178291200 ) ) ,
    new DataPair ( 20 , new BigInteger ( 2432902008176640000 ) ) ,
    //new DataPair ( 30 , new BigInteger ( 265252859812191058636308480000000 ) ) ,
    //new DataPair ( 40 , new BigInteger ( 815915283247897734345611269596115894272000000000 ) ) ,
  } ;
  [ Test ]
  public void correctIterative ( ) {
    for ( int i = 0 ; i < data.Length ; ++i ) { Assert.AreEqual ( data[i].expected , Factorial_BigInteger.iterative ( data[i].i ) ) ; }
  }
  [ Test ]
  public void correctRecursive ( ) {
    for ( int i = 0 ; i < data.Length ; ++i ) { Assert.AreEqual ( data[i].expected , Factorial_BigInteger.recursive ( data[i].i ) ) ; }
  }
  //[ Test ] 
  public void negativeIterative ( ) {
    for ( int i = -20 ; i < 0 ; ++i ) { Factorial_BigInteger.iterative ( (ulong) i ) ; }
  }
  //[ Test ] 
  public void negativeRecursive ( ) {
    for ( int i = -20 ; i < 0 ; ++i ) { Factorial_BigInteger.recursive ( (ulong) i ) ; }
  }
  //  Dummy main to keep the compiler from issuing an error.
  public static int Main ( string[] args ) { return 0 ; }
}