Add Mail::YAML#load compatible with Psych 3.x and Psych 4.x.

Co-authored-by: Vít Ondruch <[email protected]>

lib/mail/message.rb

@@ -2,7 +2,7 @@
 # frozen_string_literal: true
 require 'mail/constants'
 require 'mail/utilities'
-require 'yaml'
+require 'mail/yaml'
 
 module Mail
   # The Message class provides a single point of access to all things to do with an
@@ -1841,7 +1841,7 @@ def to_yaml(opts = {})
     end
 
     def self.from_yaml(str)
-      hash = YAML.load(str)
+      hash = Mail::YAML.load(str)
       m = self.new(:headers => hash['headers'])
       hash.delete('headers')
       hash.each do |k,v|

lib/mail/yaml.rb

@@ -0,0 +1,30 @@
+require 'yaml'
+
+module Mail
+  module YAML
+    def self.load(yaml)
+      permitted_classes = [
+        Symbol,
+
+        Mail::Body,
+
+        # Delivery methods as listed in mail/configuration.rb
+        Mail::SMTP,
+        Mail::Sendmail,
+        Mail::Exim,
+        Mail::FileDelivery,
+        Mail::SMTPConnection,
+        Mail::TestMailer,
+        Mail::LoggerDelivery,
+
+        Mail.delivery_method.class,
+      ]
+
+      if Gem::Version.new(Psych::VERSION) >= Gem::Version.new('3.1.0.pre1')
+        ::YAML.safe_load(yaml, :permitted_classes => permitted_classes)
+      else
+        ::YAML.safe_load(yaml, permitted_classes)
+      end
+    end
+  end
+end

spec/mail/message_spec.rb

@@ -194,7 +194,7 @@ def create_mail_with_splat_args
 
       it "should serialize the basic information to YAML" do
         yaml = @yaml_mail.to_yaml
-        yaml_output = YAML.load(yaml)
+        yaml_output = Mail::YAML.load(yaml)
         expect(yaml_output['headers']['To']).to       eq "[email protected]"
         expect(yaml_output['headers']['Cc']).to       eq "[email protected]"
         expect(yaml_output['headers']['Subject']).to  eq "subject"
@@ -212,7 +212,7 @@ def create_mail_with_splat_args
       it "should serialize a Message with a custom delivery_handler" do
         @yaml_mail.delivery_handler = DeliveryAgent
         yaml = @yaml_mail.to_yaml
-        yaml_output = YAML.load(yaml)
+        yaml_output = Mail::YAML.load(yaml)
         expect(yaml_output['delivery_handler']).to eq "DeliveryAgent"
       end
 
@@ -224,15 +224,15 @@ def create_mail_with_splat_args
 
       it "should not deserialize a delivery_handler that does not exist" do
         yaml = @yaml_mail.to_yaml
-        yaml_hash = YAML.load(yaml)
+        yaml_hash = Mail::YAML.load(yaml)
         yaml_hash['delivery_handler'] = "NotARealClass"
         deserialized = Mail::Message.from_yaml(yaml_hash.to_yaml)
         expect(deserialized.delivery_handler).to be_nil
       end
 
       it "should deserialize parts as an instance of Mail::PartsList" do
         yaml = @yaml_mail.to_yaml
-        yaml_hash = YAML.load(yaml)
+        yaml_hash = Mail::YAML.load(yaml)
         deserialized = Mail::Message.from_yaml(yaml_hash.to_yaml)
         expect(deserialized.parts).to be_kind_of(Mail::PartsList)
       end

spec/mail/parts_list_spec.rb

@@ -95,6 +95,6 @@
 
   it "should have a round-tripping YAML serialization" do
     p = Mail::PartsList.new([1, 2])
-    expect(YAML.load(YAML.dump(p))).to eq(p)
+    expect(Mail::YAML.load(YAML.dump(p))).to eq(p)
   end
 end

spec/mail/yaml_spec.rb

@@ -0,0 +1,13 @@
+# encoding: utf-8
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Mail::YAML do
+
+  describe "#load" do
+
+    it 'loads YAML' do
+      expect(Mail::YAML.load('{}')).to eq({})
+    end
+  end
+end