minor: tweaks and some more test cases

lib/mongo/cursor.rb

@@ -84,7 +84,7 @@ def count
     # This method overrides any sort order specified in the Collection#find
     # method, and only the last sort applied has an effect
     def sort(order)
-      raise InvalidOperation, "can't call Cursor#sort on a used cursor" if @query_run
+      check_modifiable
       @query.order_by = order
       self
     end
@@ -100,7 +100,7 @@ def limit(number_to_return)
       raise ArgumentError, "limit requires an integer" unless number_to_return.is_a? Integer
 
       @query.number_to_return = number_to_return
-      return self
+      self
     end
 
     # Skips the first +number_to_skip+ results of this cursor.
@@ -114,7 +114,7 @@ def skip(number_to_skip)
       raise ArgumentError, "skip requires an integer" unless number_to_skip.is_a? Integer
 
       @query.number_to_skip = number_to_skip
-      return self
+      self
     end
 
     # Iterate over each document in this cursor, yielding it to the given

test/test_cursor.rb

@@ -57,22 +57,27 @@ def test_count
 
     assert_equal 0, @@db['acollectionthatdoesn'].count()
   end
-  
+
   def test_sort
     @@coll.clear
-    5.times{|x| @@coll.insert({"a" => x, "b" => 5-x}) }
-    
-    assert_kind_of Cursor, @@coll.find().sort({:a=>1})
-    
+    5.times{|x| @@coll.insert({"a" => x}) }
+
+    assert_kind_of Cursor, @@coll.find().sort({:a => 1})
+
     assert_equal 0, @@coll.find().sort({:a => 1}).next_object["a"]
     assert_equal 4, @@coll.find().sort({:a => -1}).next_object["a"]
-
-    assert_equal 1, @@coll.find().sort({:a => -1, :b => 1}).next_object["b"]
-    assert_equal 5, @@coll.find().sort({:a => 1, :b => -1}).next_object["b"]
-    
+    assert_equal 0, @@coll.find().sort(["a"]).next_object["a"]
+
+    assert_kind_of Cursor, @@coll.find().sort({:a => -1, :b => 1})
+
     assert_equal 4, @@coll.find().sort({:a => 1}).sort({:a => -1}).next_object["a"]
     assert_equal 0, @@coll.find().sort({:a => -1}).sort({:a => 1}).next_object["a"]
-
+
+    cursor = @@coll.find()
+    cursor.next_object()
+    assert_raise InvalidOperation do
+      cursor.sort(["a"])
+    end
   end
 
   def test_limit