車窓からのTDD http://objectclub.jp/technicaldoc/testing/stack_tdd.pdf/view の写経

Stack.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace Stack
{
  public class EmptyStackException : Exception
  {
  }

  public class Stack
  {
    private int[] values = new int[10];

    public bool IsEmpty
    {
      get
      {
        return size == 0;
      }
    }

    public void Push(int value)
    {
      this.values[size] = value;
      size++;
    }

    public int Top
    {
      get
      {
        AssertEmpty();

        return this.values[size-1];
      }
    }

    private void AssertEmpty()
    {
      if (IsEmpty)
      {
        throw new EmptyStackException();
      }
    }

    private int size;
    public int Size
    {
      get
      {
        return size;
      }
    }

    public void Pop()
    {
      AssertEmpty();

      size--;
    }
  }

  [TestClass]
  public class StackTest
  {
    private Stack stack;

    [TestInitialize]
    public void SetUp()
    {
      stack = new Stack();
    }

    [TestMethod]
    public void Stack作成後は空()
    {
      Assert.IsTrue(stack.IsEmpty);
    }

    [TestMethod]
    public void Push後にTopで同じ値が取得できる()
    {
      stack.Push(1);
      Assert.AreEqual(1, stack.Top);
      Assert.IsFalse(stack.IsEmpty);
    }

    [TestMethod]
    public void Push後にSizeが増える()
    {
      stack.Push(1);
      Assert.AreEqual(1, stack.Size);
      stack.Push(1);
      Assert.AreEqual(2, stack.Size);
    }

    [TestMethod]
    public void Push前にPopしたら例外発生()
    {
      try
      {
        stack.Pop();
        Assert.Fail();
      }
      catch (EmptyStackException)
      {
      }
    }

    [TestMethod]
    public void Push前にTopしたら例外発生()
    {
      try
      {
        var top = stack.Top;
        Assert.Fail();
      }
      catch (EmptyStackException)
      {
      }
    }

    [TestMethod]
    public void Push後にPopしたら例外なしでTopを取り除く()
    {
      stack.Push(1);
      stack.Pop();
      Assert.AreEqual(0, stack.Size);
    }

    [TestMethod]
    public void Stack構造になっている()
    {
      stack.Push(1);
      stack.Push(2);
      Assert.AreEqual(2, stack.Top);
      stack.Pop();
      Assert.AreEqual(1, stack.Top);
    }
  }
}