Fixed a typo, added unit test.

Author: Quantumplation

NTestDataBuilder.Tests/BuildTests.cs

@@ -30,5 +30,19 @@ public void GivenBuilderWithMethodCalls_WhenCallingBuild_ThenReturnAnObjectWithT
             Assert.That(customer.LastName, Is.EqualTo("Kocaj"));
             Assert.That(customer.YearJoined, Is.EqualTo(2010));
         }
+
+        [Test]
+        public void GivenBuilder_WhenCallingSet_ShouldOverrideValues()
+        {
+            var builder = new CustomerBuilder()
+                .Set(x => x.FirstName, "Pi")
+                .Set(x => x.LastName, "Lanningham")
+                .Set(x => x.YearJoined, 2014);
+
+            var customer = builder.Build();
+            Assert.That(customer.FirstName, Is.EqualTo("Pi"));
+            Assert.That(customer.LastName, Is.EqualTo("Lanningham"));
+            Assert.That(customer.YearJoined, Is.EqualTo(2014));
+        }
     }
 }

NTestDataBuilder/TestDataBuilder.cs

@@ -78,7 +78,7 @@ protected virtual void AlterProxy(TObject proxy) {}
         public TBuilder Set<TValue>(Expression<Func<TObject, TValue>> property, TValue value)
         {
             _properties[GetPropertyName(property)] = value;
-            return (TBuilder)this;
+            return this as TBuilder;
         }
 
         /// <summary>