File.size? actually returns nil instead of false

lib/fakefs/file.rb

@@ -51,7 +51,11 @@ module FakeFS
     end
 
     def self.size?(path)
-      exists?(path) && !size(path).zero?
+      if exists?(path) && !size(path).zero?
+        true
+      else
+        nil
+      end
     end
 
     def self.const_missing(name)

test/fakefs_test.rb

@@ -214,7 +214,7 @@ class FakeFSTest < Test::Unit::TestCase
       f << 'Yada Yada'
     end
     assert File.size?(path)
-    assert ! File.size?("/path/to/other.txt")
+    assert_nil File.size?("/path/to/other.txt")
   end
 
   def test_can_check_size?_of_empty_file
@@ -222,7 +222,7 @@ class FakeFSTest < Test::Unit::TestCase
     File.open(path, 'w') do |f|
       f << ''
     end
-    assert ! File.size?("/path/to/file.txt")
+    assert_nil File.size?("/path/to/file.txt")
   end
 
   def test_can_read_with_File_readlines