adds another test case in the monitors suite

activesupport/test/file_update_checker_with_enumerable_test_cases.rb

@@ -93,7 +93,7 @@ def test_should_cache_updated_result_until_execute
     assert !checker.updated?
   end
 
-  def test_should_execute_the_block_if_files_change_in_a_watched_directory
+  def test_should_execute_the_block_if_files_change_in_a_watched_directory_one_extension
     i = 0
 
     checker = new_checker([], @tmpdir => :rb) { i += 1 }
@@ -104,6 +104,22 @@ def test_should_execute_the_block_if_files_change_in_a_watched_directory
     assert_equal 1, i
   end
 
+  def test_should_execute_the_block_if_files_change_in_a_watched_directory_several_extensions
+    i = 0
+
+    checker = new_checker([], @tmpdir => [:rb, :txt]) { i += 1 }
+
+    touch("#{@tmpdir}/foo.rb")
+
+    assert checker.execute_if_updated
+    assert_equal 1, i
+
+    touch("#{@tmpdir}/foo.rb")
+
+    assert checker.execute_if_updated
+    assert_equal 2, i
+  end
+
   def test_should_not_execute_the_block_if_the_file_extension_is_not_watched
     i = 0