better error checking for database names

lib/mongo/db.rb

@@ -114,7 +114,21 @@ module XGen
         # instance and connect to that one. On socket error or if we recieve a
         # "not master" error, we again find the master of the pair.
         def initialize(db_name, nodes, options={})
-          raise "Invalid DB name \"#{db_name}\" (must be non-nil, non-zero-length, and can not contain \".\")" if !db_name || (db_name && db_name.length > 0 && db_name.include?("."))
+          case db_name
+          when Symbol, String
+          else
+            raise TypeError, "db_name must be a string or symbol"
+          end
+
+          [" ", ".", "$", "/", "\\"].each do |invalid_char|
+            if db_name.include? invalid_char
+              raise InvalidName, "database names cannot contain the character '#{invalid_char}'"
+            end
+          end
+          if db_name.empty?
+            raise InvalidName, "database name cannot be the empty string"
+          end
+
           @name, @nodes = db_name, nodes
           @strict = options[:strict]
           @pk_factory = options[:pk]

tests/test_mongo.rb

@@ -17,6 +17,17 @@ class MongoTest < Test::Unit::TestCase
     @mongo.db('ruby-mongo-test').error
   end
 
+  def test_invalid_database_names
+    assert_raise TypeError do @mongo.db(4) end
+
+    assert_raise InvalidName do @mongo.db('') end
+    assert_raise InvalidName do @mongo.db('te$t') end
+    assert_raise InvalidName do @mongo.db('te.t') end
+    assert_raise InvalidName do @mongo.db('te\\t') end
+    assert_raise InvalidName do @mongo.db('te/t') end
+    assert_raise InvalidName do @mongo.db('te st') end
+  end
+
   def test_database_info
     @mongo.drop_database('ruby-mongo-info-test')
     @mongo.db('ruby-mongo-info-test').collection('info-test').insert('a' => 1)