[NPE-5] Address Singleton

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    fakememcached (0.1.1)
+    fakememcached (0.1.3)
 
 GEM
   remote: http://rubygems.org/
@@ -17,3 +17,6 @@ DEPENDENCIES
   fakememcached!
   rake
   rspec (~> 1.3.0)
+
+BUNDLED WITH
+   2.1.4

lib/fakememcached/cache_entry.rb

@@ -4,14 +4,14 @@ class CacheEntry
 
     def initialize(value, ttl, marshal)
       if marshal
-        @value = Marshal.dump(value)
+        @value = singleton_safe_marshal(value)
       else
         @value = value.to_s
       end
 
       @expires_at = Time.now + ttl
     end
-    
+
     def expired?
       Time.now > @expires_at
     end
@@ -23,13 +23,27 @@ def increment(amount = 1)
     def decrement(amount = 1)
       @value = (@value.to_i - amount).to_s
     end
-    
+
     def unmarshal
-      Marshal.load(@value)
+      singleton_safe_unmarshal
     end
-    
+
     def to_i
       @value.to_i
     end
+
+    def singleton_safe_marshal(value)
+      # Rspec mocks create singletons out of objects in order to track calls
+      # However, singletons can't be dumped, so skip marshaling
+      return value if value.singleton_methods.any?
+      Marshal.dump(value)
+    end
+
+    def singleton_safe_unmarshal
+      # Rspec mocks create singletons out of objects in order to track calls
+      # However, singletons can't be dumped, so skip marshaling
+      return value if value.singleton_methods.any?
+      Marshal.load(value)
+    end
   end
 end

lib/fakememcached/version.rb

@@ -2,7 +2,7 @@ class FakeMemcached
   module Version
     MAJOR = 0
     MINOR = 1
-    PATCH = 2
+    PATCH = 3
     STRING = [MAJOR, MINOR, PATCH].join('.')
   end
 end