using System;
using Xunit;

namespace SemiColinGames.Tests {

  public class HistoryTests {
    public static int[] ToArray(History<int> history) {
      int[] result = new int[history.Length];
      for (int i = 0; i < history.Length; i++) {
        result[i] = history[i];
      }
      return result;
    }

    [Fact]
    public void TestLength() {
      var h = new History<int>(3);
      Assert.Equal(3, h.Length);
    }

    [Fact]
    public void TestGetFromEmpty() {
      var ints = new History<int>(3);
      Assert.Equal(0, ints[0]);
      Assert.Equal(0, ints[1]);
      Assert.Equal(0, ints[2]);

      var objects = new History<Object>(1);
      Assert.Null(objects[0]);
    }

    [Fact]
    public void TestAdds() {
      var h = new History<int>(3);
      Assert.Equal("0 0 0", String.Join(" ", ToArray(h)));
      h.Add(2);
      Assert.Equal("2 0 0", String.Join(" ", ToArray(h)));
      h.Add(3);
      h.Add(5);
      Assert.Equal("5 3 2", String.Join(" ", ToArray(h)));
      h.Add(7);
      Assert.Equal("7 5 3", String.Join(" ", ToArray(h)));
      h.Add(11);
      h.Add(13);
      Assert.Equal("13 11 7", String.Join(" ", ToArray(h)));
    }

    [Fact]
    public void TestThrowsExceptions() {
      var h = new History<int>(3);
      Assert.Throws<IndexOutOfRangeException>(() => h[-1]);
      Assert.Throws<IndexOutOfRangeException>(() => h[3]);
    }
  }
}