spec

spec/mail/message_spec.rb

@@ -1437,6 +1437,26 @@ def message_headers_should_match(message, other)
         expect(mail.parts.last.content_transfer_encoding).to match(/7bit|8bit|binary/)
       end
 
+      it "should not add an empty charset" do
+        mail = Mail.new do
+          to 'mikel@test.lindsaar.net'
+          from 'bob@test.lindsaar.net'
+          subject 'Multipart email'
+          text_part do
+            body 'This is plain text'
+          end
+          html_part do
+            content_type 'text/html; charset=UTF-8'
+            body '<h1>This is HTML</h1>'
+          end
+        end
+        mail.charset = nil
+
+        expect(mail.multipart?).to eq true
+        expect(mail.parts.count).to eq 2
+        expect(mail.encoded.scan(/charset=UTF-8/).count).to eq 2
+      end
+
       describe "convert_to_multipart" do
         subject do
           read_fixture('emails', 'attachment_emails', 'attachment_only_email.eml').tap(&:convert_to_multipart)