file and line support.diff

diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index 739823b..45000bc 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -75,6 +75,27 @@ module ActiveSupport
     alias :assert_not_respond_to :refute_respond_to
     alias :assert_not_same :refute_same
 
+    class FileAndLineFilter < Struct.new(:klass, :file, :line)
+      def === method
+        return false unless klass.method_defined? method
+        test_file, test_line = klass.instance_method(method).source_location
+        test_file == file && test_line == line
+      end
+    end
+
+    def self.run reporter, options = {}
+      if file_and_line? options[:filter]
+        options = options.dup
+        options[:filter] =~ /^(.*):(\d+)/
+        options[:filter] = FileAndLineFilter.new(self, $1, $2.to_i)
+      end
+      super(reporter, options)
+    end
+
+    def self.file_and_line? option
+      option && option =~ /:\d+/
+    end
+
     # Fails if the block raises an exception.
     #
     #   assert_nothing_raised do