Added Limit method

RedStar.Amounts.Tests/AmountMathTests.cs

@@ -67,18 +67,5 @@ public void TestAbs()
             var zeroAmount = new Amount(0, LengthUnits.CentiMeter);
             Assert.Equal(new Amount(0, LengthUnits.CentiMeter), AmountMath.Abs(zeroAmount));
         }
-
-        [Fact]
-        public void TestAverage()
-        {
-            var amount1 = new Amount(10, TemperatureUnits.DegreeCelcius);
-            var amount2 = new Amount(20, TemperatureUnits.DegreeCelcius);
-            var amount3 = new Amount(25, TemperatureUnits.DegreeCelcius);
-            var amount4 = new Amount(18, TemperatureUnits.DegreeCelcius);
-
-            var list = new[] {amount1, amount2, amount3, amount4};
-
-            Assert.Equal(new Amount(18.25, TemperatureUnits.DegreeCelcius), list.Average());
-        }
     }
 }

RedStar.Amounts.Tests/ExtensionsTests.cs

@@ -0,0 +1,71 @@
+using RedStar.Amounts.StandardUnits;
+using Xunit;
+
+namespace RedStar.Amounts.Tests
+{
+    public class ExtensionsTests
+    {
+        private class MyClass
+        {
+            public Amount MyAmount { get; set; }
+        }
+
+        [Fact]
+        public void SumTest()
+        {
+            var a = new Amount(3000.0, LengthUnits.Meter);
+            var b = new Amount(3500.0, LengthUnits.Meter);
+            var c = new Amount(1000.0, LengthUnits.Meter);
+            var amounts = new[] { a, b, c };
+
+            var expected = new Amount(7500.0, LengthUnits.Meter);
+
+            var sum = amounts.Sum();
+
+            Assert.Equal(expected, sum);
+        }
+
+        [Fact]
+        public void SumWithSelectorTest()
+        {
+            var a = new MyClass { MyAmount = new Amount(3000.0, LengthUnits.Meter) };
+            var b = new MyClass { MyAmount = new Amount(3500.0, LengthUnits.Meter) };
+            var c = new MyClass { MyAmount = new Amount(1000.0, LengthUnits.Meter) };
+            var amounts = new[] { a, b, c };
+
+            var expected = new Amount(7500.0, LengthUnits.Meter);
+
+            var sum = amounts.Sum(x => x.MyAmount);
+
+            Assert.Equal(expected, sum);
+        }
+
+        [Fact]
+        public void TestAverage()
+        {
+            var amount1 = new Amount(10, TemperatureUnits.DegreeCelcius);
+            var amount2 = new Amount(20, TemperatureUnits.DegreeCelcius);
+            var amount3 = new Amount(25, TemperatureUnits.DegreeCelcius);
+            var amount4 = new Amount(18, TemperatureUnits.DegreeCelcius);
+
+            var list = new[] { amount1, amount2, amount3, amount4 };
+
+            Assert.Equal(new Amount(18.25, TemperatureUnits.DegreeCelcius), list.Average());
+        }
+
+        [Fact]
+        public void TestLimit()
+        {
+            var tooLowAmount = new Amount(10, TemperatureUnits.DegreeCelcius);
+            var tooHighAmount = new Amount(100, TemperatureUnits.DegreeCelcius);
+            var inBetweenAmount = new Amount(50, TemperatureUnits.DegreeCelcius);
+
+            var minimum = new Amount(40, TemperatureUnits.DegreeCelcius);
+            var maximum = new Amount(60, TemperatureUnits.DegreeCelcius);
+
+            Assert.Equal(new Amount(40, TemperatureUnits.DegreeCelcius), tooLowAmount.Limit(minimum, maximum));
+            Assert.Equal(new Amount(60, TemperatureUnits.DegreeCelcius), tooHighAmount.Limit(minimum, maximum));
+            Assert.Equal(new Amount(50, TemperatureUnits.DegreeCelcius), inBetweenAmount.Limit(minimum, maximum));
+        }
+    }
+}

RedStar.Amounts.Tests/RedStar.Amounts.Tests.csproj

@@ -61,6 +61,7 @@
   <ItemGroup>
     <Compile Include="AmountMathTests.cs" />
     <Compile Include="AmountTests.cs" />
+    <Compile Include="ExtensionsTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="UnitManagerTests.cs" />
     <Compile Include="UnitTests.cs" />

RedStar.Amounts/Extensions.cs

@@ -22,5 +22,14 @@ public static Amount Average(this IEnumerable<Amount> source)
             var count = source.Count();
             return sum / count;
         }
+
+        /// <summary>
+        /// Limits a given Amount to be between the minimum and maximum provided. If the given Amount is lower than the minimum, the minimum will be returned.
+        /// If it is higher than the maximum, the maximum will be returned. If it is between the minimum and maximum, the value will be returned unchanged.
+        /// </summary>
+        public static Amount Limit(this Amount amount, Amount minimum, Amount maximum)
+        {
+            return AmountMath.Max(minimum, AmountMath.Min(amount, maximum));
+        }
     }
 }