Merge branch 'Add_Object_IsNull' of https://github.com/dupdob/NFluent into isNullIntegration

Conflicts:
	NFluent.Tests/EdgeCasesTest.cs

Author: tpierrain

NFluent.Tests/EdgeCasesTest.cs

@@ -41,9 +41,9 @@ public void IsATest()
         [Test]
         public void NumberTypeChanges()
         {
-            var test = 4L;
+            const long Test = 4L;
 
-            Check.That(test).IsEqualTo(4);
+            Check.That(Test).IsEqualTo(4);
         }
     }
 }

NFluent.Tests/ObjectRelatedTest.cs

@@ -40,6 +40,32 @@ public void IsDistinctWorks()
             Check.That(new object()).IsDistinctFrom(new object());
         }
 
+        [Test]
+        public void IsNullWork()
+        {
+            Check.That((object)null).IsNull();
+        }
+
+        [Test]
+        [ExpectedException(typeof(FluentCheckException), ExpectedMessage = "\nThe checked object must be null.\nThe checked object:\n\t[System.Object]")]
+        public void IsNullFailsProperly()
+        {
+            Check.That(new object()).IsNull();
+        }
+
+        [Test]
+        public void IsNotNullWork()
+        {
+            Check.That(new object()).IsNotNull();
+        }
+
+        [Test]
+        [ExpectedException(typeof(FluentCheckException), ExpectedMessage = "\nThe checked object must not be null.\nThe checked object:\n\t[null]")]
+        public void IsNotNullFailsProperly()
+        {
+            Check.That((object)null).IsNotNull();
+        }
+
         [Test]
         [ExpectedException(typeof(FluentCheckException), ExpectedMessage = "\nThe checked object must have be an instance distinct from expected one.\nThe checked object:\n\t[System.Object]\nThe expected object: distinct from\n\t[System.Object]")]
         public void IsDistinctFailsProperly()

NFluent/Assertions/ObjectCheckExtensions.cs

@@ -149,6 +149,58 @@ public static ICheckLink<ICheck<object>> InheritsFrom<T>(this ICheck<object> che
                 string.Format("\nThe checked expression is part of the inheritance hierarchy or of the same type than the specified one.\nIndeed, checked expression type:\n\t[{0}]\nis a derived type of\n\t[{1}].", instanceType.ToStringProperlyFormated(), expectedBaseType.ToStringProperlyFormated()));
         }
 
+        /// <summary>
+        /// Checks that the actual expression is null.
+        /// </summary>
+        /// <param name="check">The fluent check to be extended.</param>
+        /// <returns>A check link.</returns>
+        /// <exception cref="FluentCheckException">Is the value is not null.</exception>
+        public static ICheckLink<ICheck<object>> IsNull(this ICheck<object> check)
+        {
+            var runnableCheck = check as IRunnableCheck<object>;
+            var negated = runnableCheck.Negated;
+            var value = runnableCheck.Value;
+
+            var message = IsNullImpl(value, negated);
+            if (!string.IsNullOrEmpty(message))
+            {
+                throw new FluentCheckException(FluentMessage.BuildMessage(message).For("object").On(value).ToString());
+            }
+
+            return new CheckLink<ICheck<object>>(check);
+        }
+
+        /// <summary>
+        /// Checks that the actual expression is not null.
+        /// </summary>
+        /// <param name="check">The fluent check to be extended.</param>
+        /// <returns>A check link.</returns>
+        /// <exception cref="FluentCheckException">Is the value is null.</exception>
+        public static ICheckLink<ICheck<object>> IsNotNull(this ICheck<object> check)
+        {
+            var runnableCheck = check as IRunnableCheck<object>;
+            var negated = runnableCheck.Negated;
+            var value = runnableCheck.Value;
+
+            var message = IsNullImpl(value, !negated);
+            if (!string.IsNullOrEmpty(message))
+            {
+                throw new FluentCheckException(FluentMessage.BuildMessage(message).For("object").On(value).ToString());
+            }
+
+            return new CheckLink<ICheck<object>>(check);
+        }
+
+        private static string IsNullImpl(object value, bool negated)
+        {
+            if (!negated)
+            {
+                return value == null ? null : "The {0} must be null.";
+            }
+
+            return value == null ? "The {0} must not be null." : null;
+        }
+
         /// <summary>
         /// Checks that the actual value has an expected reference.
         /// </summary>