RUBY-267 Cursor#alive?

lib/mongo/cursor.rb

@@ -307,6 +307,13 @@ module Mongo
     # @return [Boolean]
     def closed?; @closed; end
 
+    # Is this cursor alive on the server?
+    #
+    # @return [Boolean]
+    def alive?
+      @cursor_id && @cursor_id != 0
+    end
+
     # Returns an integer indicating which query options have been selected.
     #
     # @return [Integer]

test/cursor_test.rb

@@ -32,6 +32,21 @@ class CursorTest < Test::Unit::TestCase
     assert_kind_of Numeric, explaination['nscanned']
   end
 
+  def test_alive
+    batch = []
+    5000.times do |n|
+      batch << {:a => n}
+    end
+    @@coll.insert(batch)
+    cursor = @@coll.find
+    assert !cursor.alive?
+    cursor.next
+    assert cursor.alive?
+    cursor.close
+    assert !cursor.alive?
+    @@coll.remove
+  end
+
   def test_count
     @@coll.remove