public void GivenSourceIsNullWhenCallingWithThenShallCreateDefaultObject()
{
// ARRANGE
GuineaPig noPig = null;
// ACT
var noClone = noPig.With(nameof(noPig.Age), 1);
// ASSERT
Assert.IsNull(noClone);
}
public void WhenCallingWithThenCloneGetsNewValueAndOriginalKeepsOldValue()
{
// ARRANGE
var pig = new GuineaPig("Fluffy", 0);
var originalPig = pig;
// ACT
for (int i = 0; i < 100000; i++) // for profiling
{
pig = pig.With(nameof(pig.Age), pig.Age + 1);
}
pig = pig.With(nameof(pig.Name), "Shawn");
// ASSERT
// Check the new pig
Assert.AreEqual("Shawn", pig.Name);
Assert.AreEqual(100000, pig.Age);
// Check that original pig has not mutated
Assert.AreEqual(0, originalPig.Age);
Assert.AreEqual("Fluffy", originalPig.Name);
}