Implemented CPCoding for CPNull.

Foundation/CPNull.j

@@ -25,7 +25,7 @@
 
 var CPNullSharedNull = nil;
 
-/*! 
+/*!
     @class CPNull
     @ingroup foundation
     @brief An object representation of \c nil.
@@ -41,7 +41,7 @@ var CPNullSharedNull = nil;
 {
     if (CPNullSharedNull)
         return CPNullSharedNull;
-        
+
     return [super alloc];
 }*/
 /*!
@@ -53,8 +53,27 @@ var CPNullSharedNull = nil;
 {
     if (!CPNullSharedNull)
         CPNullSharedNull = [[CPNull alloc] init];
-        
+
     return CPNullSharedNull;
 }
 
+/*!
+    Returns CPNull null.
+    @param aCoder the coder from which to do nothing
+    @return [CPNull null]
+*/
+- (id)initWithCoder:(CPCoder)aCoder
+{
+    return [CPNull null];
+}
+
+/*!
+    Writes out nothing to the specified coder.
+    @param aCoder the coder to which nothing will
+    be written
+*/
+- (void)encodeWithCoder:(CPCoder)aCoder
+{
+}
+
 @end

Tests/Foundation/CPNullTest.j

@@ -0,0 +1,12 @@
+@import <Foundation/CPNull.j>
+@import <Foundation/CPKeyedArchiver.j>
+@import <Foundation/CPKeyedUnarchiver.j>
+
+@implementation CPNullTest : OJTestCase
+
+- (void)testArchiving
+{
+    [self assert:[CPKeyedUnarchiver unarchiveObjectWithData:[CPKeyedArchiver archivedDataWithRootObject:[CPNull null]]] equals:[CPNull null]];
+}
+
+@end