Fix yaml deserialization of ActiveSupport::Duration

This ensures the duration's @parts hash has a default value, to avoid this regression introduced in 5.1:

  YAML.load(YAML.dump(10.minutes)) + 1  # => NoMethodError: undefined method `+' for nil:NilClass

1 files changed, 8 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 39deb2313f..19b2d84fc8 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -334,6 +334,14 @@ module ActiveSupport
       to_i
     end
 
+    def init_with(coder) #:nodoc:
+      initialize(coder["value"], coder["parts"])
+    end
+
+    def encode_with(coder) #:nodoc:
+      coder.map = { "value" => @value, "parts" => @parts }
+    end
+
     # Build ISO 8601 Duration string for this duration.
     # The +precision+ parameter can be used to limit seconds' precision of duration.
     def iso8601(precision: nil)