Since I haven't blogged for months, might as well bust a Ménage à trois post.
In this post you will learn the following:
- An implementation of IEnumerable<T>
- Fluent interfaces
- Simpe implementation of the Specification Pattern
To begin, here's the test...
using System.Collections;
using System.Collections.Generic;
using MbUnit.Framework;
using specification;
namespace test
{
[TestFixture]
public class InventoryTest
{
[Test]
public void Add_ShouldBuildInventory_UsingAdd_ButItIsNotAsCool()
{
Inventory musicalInstrumentInventory = new Inventory();
musicalInstrumentInventory.Add(new MusicalInstrument("Guitar"));
musicalInstrumentInventory.Add(new MusicalInstrument("Turntables"));
musicalInstrumentInventory.Add(new MusicalInstrument("Drums"));
musicalInstrumentInventory.Add(new MusicalInstrument("Banjo"));
int totalMusicalInstruments = 0;
IEnumerator enumerator = musicalInstrumentInventory.GetEnumerator();
while (enumerator.MoveNext())
{
totalMusicalInstruments++;
}
Assert.AreEqual(4, totalMusicalInstruments);
}
[Test]
public void With_ShouldBuildInventory_UsingFluentInterface()
{
Inventory musicalInstrumentInventory = new Inventory()
.With(new MusicalInstrument("Guitar"))
.With(new MusicalInstrument("Turntables"))
.With(new MusicalInstrument("Drums"))
.With(new MusicalInstrument("Banjo"));
int totalMusicalInstruments = 0;
IEnumerator enumerator = musicalInstrumentInventory.GetEnumerator();
while (enumerator.MoveNext())
{
totalMusicalInstruments++;
}
Assert.AreEqual(4, totalMusicalInstruments);
}
[Test]
public void FindAll_ShouldFindGuitar()
{
MusicalInstrument guitar = new MusicalInstrument("Guitar");
Inventory musicalInstrumentInventory = new Inventory()
.With(guitar)
.With(new MusicalInstrument("Turntables"))
.With(new MusicalInstrument("Drums"))
.With(new MusicalInstrument("Banjo"));
MusicalInstrument resultGuitar =
new List<MusicalInstrument>
(
musicalInstrumentInventory.FindAll(new GetGuitarSpecification())
)[0];
Assert.IsTrue(guitar.Equals(resultGuitar));
}
private class GetGuitarSpecification : ISpecification<MusicalInstrument>
{
public bool IsSatisfiedBy(MusicalInstrument item)
{
return item.Name.Equals("Guitar");
}
}
}
}
Now the code...
using System.Collections;
using System.Collections.Generic;
namespace specification
{
public class Inventory : IEnumerable<MusicalInstrument>
{
private List<MusicalInstrument> instruments;
public Inventory()
{
instruments = new List<MusicalInstrument>();
}
public void Add(MusicalInstrument musicalInstrument)
{
instruments.Add(musicalInstrument);
}
public Inventory With(MusicalInstrument musicalInstrument)
{
Add(musicalInstrument);
return this;
}
public IEnumerable<MusicalInstrument> FindAll(ISpecification<MusicalInstrument> specification)
{
return instruments.FindAll(delegate(MusicalInstrument instrument)
{
return specification.IsSatisfiedBy(instrument);
});
}
IEnumerator<MusicalInstrument> IEnumerable<MusicalInstrument>.GetEnumerator()
{
return instruments.GetEnumerator();
}
public IEnumerator GetEnumerator()
{
return instruments.GetEnumerator();
}
}
}
And finally the ISpecification Interface
namespace specification
{
public interface ISpecification<PersistentItem>
{
bool IsSatisfiedBy(PersistentItem item);
}
}
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