Commit d1a589f

@@ -6,9 +6,9 @@ namespace utility
 
   public static class Iterating
   {
-    public static void Each<T>(this IEnumerable<T> items, Action<T> visitor){
-      foreach (var item in items ?? Enumerable.Empty<T>()) 
-        visitor(item);
+    public static void Each<T>(this IEnumerable<T> items, Action<T> visitor)
+    {
+      foreach (var item in items ?? Enumerable.Empty<T>()) visitor(item);
     }
   }
 }

@@ -13,7 +13,8 @@ namespace utility
   {
     TResult Result();
   }
-  public static class Visiting{
+  public static class Visiting
+  {
     public static TResult AcceptAndReturnResultFrom<T, TResult>(this IVisitable<T> visitable, IValueReturningVisitor<T, TResult> visitor)
     {
       visitable.Accept(visitor);

@@ -1,6 +1,9 @@
 namespace domain
 {
+  using System.Linq;
   using System.Collections.Generic;
+  using domain;
+  using utility;
 
   public class Capacity
   {
@@ -23,12 +26,15 @@ namespace domain
 
     public IQuantity AvailableFor(Month month)
     {
-      return new Quantity(0, new BOED());
-      //return this
-        //.increases
-        //.Where(x => x.IsBeforeOrOn(month))
-        //.Sum(x => x.IncreasedCapacity());
-      return null;
+      IQuantity result = new Quantity(0, new MCF());
+      this
+        .increases
+        .Where(x => x.IsBeforeOrOn(month))
+        .Each(x =>
+        {
+          result = result.Plus(x.IncreasedCapacity());
+        });
+      return result;
     }
 
     class Increase

@@ -46,7 +46,7 @@ namespace domain
     {
       if (ReferenceEquals(null, other)) return false;
       if (ReferenceEquals(this, other)) return true;
-      return other.Amount == Amount && Equals(other.Units, Units);
+      return other.Amount == Amount && Equals(other.Units.GetType(), Units.GetType());
     }
 
     public override bool Equals(object obj)

@@ -0,0 +1,32 @@
+namespace test
+{
+  using domain;
+  using Machine.Specifications;
+
+  public class CapacitySpecs
+  {
+    Establish context = () =>
+    {
+      sut = new Capacity(0m.MCF());
+    };
+
+    static Capacity sut;
+
+    public class when_checking_what_the_available_capacity_is_for_a_given_month
+    {
+      It should_return_the_correct_capacity=()=>
+      {
+        result.ShouldEqual(120m.MCF());
+      };
+
+      Because of = () =>
+      {
+        sut.IncreaseCapacity(60m.MCF(), Month.Now());
+        sut.IncreaseCapacity(60m.MCF(), Month.Now().Next());
+        result = sut.AvailableFor(Month.Now().Next());
+      };
+
+      static IQuantity result;
+    }
+  }
+}

@@ -44,5 +44,12 @@ namespace test
         };
       }
     }
+    public class when_two_quantities_are_equal
+    {
+      It should_return_true=()=>
+      {
+        new Quantity(120, new MCF()).ShouldEqual(new Quantity(120, new MCF()));
+      };
+    }
   }
 }

@@ -56,7 +56,8 @@
     <Compile Include="ProductionScheduleSpecs.cs" />
     <Compile Include="QuantitySpecs.cs" />
     <Compile Include="RangeSpecs.cs" />
-    <!--<Compile Include="GasPlantSpecs.cs" />-->
+    <Compile Include="GasPlantSpecs.cs" />
+    <Compile Include="CapacitySpecs.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />