Test Driven Development: A developer’s safety net

gistfile1.cs

[TestMethod]
public void TestAddPositiveNumbers()
{
  Calculator cal = new Calculator();
  int result = cal.Add(2, 2);
  Assert.AreEqual(4, result);
}

gistfile2.cs

public int Add(int first, int second)
{
  throw new NotImplementedException();
}

gistfile3.cs

public void TestAddNegativeNumbers()
{
  Calculator cal = new Calculator();
  int result = cal.Add(-2, -2);
  Assert.AreEqual(-4, result);
}

gistfile4.cs

public int Add(int first, int second)
{
  return first + second;
}