fix FileUpdateChecker when file has wrong mtime (from future)

2 files changed, 17 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/file_update_checker.rb b/activesupport/lib/active_support/file_update_checker.rb
index 48c39d9370..9decbaef32 100644
--- a/activesupport/lib/active_support/file_update_checker.rb
+++ b/activesupport/lib/active_support/file_update_checker.rb
@@ -101,7 +101,9 @@ module ActiveSupport
     end
 
     def updated_at(paths)
-      @updated_at || paths.map { |path| File.mtime(path) }.max || Time.at(0)
+      time_now = Time.now
+      @updated_at || paths.map { |path| File.mtime(path) }.
+        reject { |time| time > time_now }.max || Time.at(0)
     end
 
     def compile_glob(hash)
diff --git a/activesupport/test/file_update_checker_test.rb b/activesupport/test/file_update_checker_test.rb
index 8adff5de8d..9d5417b70c 100644
--- a/activesupport/test/file_update_checker_test.rb
+++ b/activesupport/test/file_update_checker_test.rb
@@ -48,6 +48,20 @@ class FileUpdateCheckerWithEnumerableTest < ActiveSupport::TestCase
     assert_equal 1, i
   end
 
+  def test_should_be_robust_to_handle_files_with_wrong_modified_time
+    i = 0
+    time = 1.year.from_now # wrong mtime from the future
+    File.utime time, time, FILES[2]
+
+    checker = ActiveSupport::FileUpdateChecker.new(FILES){ i += 1 }
+
+    sleep(0.1)
+    FileUtils.touch(FILES[0..1])
+
+    assert checker.execute_if_updated
+    assert_equal 1, i
+  end
+
   def test_should_cache_updated_result_until_execute
     i = 0
     checker = ActiveSupport::FileUpdateChecker.new(FILES){ i += 1 }