Only validate emails on create

Previously we had allowed '+' style addressing but it was removed
due to fraud concerns. However the validation for this now causes
a petition save to fail if the original email address is now valid
and the creator_signature association is loaded.

We can fix this by moving the email validations to on creation only
since the email address shouldn't be updated other than when it is
anonymised after the 12 month window.

Author: pixeltrix

app/models/staged/validations/email.rb

@@ -4,7 +4,7 @@ module Email
       extend ActiveSupport::Concern
 
       included do
-        validates :email, presence: true, email: { allow_blank: true }
+        validates :email, presence: true, email: { allow_blank: true }, on: :create
       end
     end
   end

app/models/staged/validations/multiple_signers.rb

@@ -4,7 +4,7 @@ module MultipleSigners
       extend ActiveSupport::Concern
 
       included do
-        validate do |signature|
+        validate on: :create do |signature|
           matcher = ::Signature.where(:email => signature.email, :petition_id => signature.petition_id)
           matcher = matcher.where("signatures.id != ?", signature.id) unless signature.new_record?
           existing_email_address_count = matcher.count

spec/models/petition_spec.rb

@@ -1897,6 +1897,31 @@
         end
       end
     end
+
+    context "when the creator's signature is now invalid" do
+      let(:creator) { petition.creator_signature }
+
+      before do
+        creator.update_column(:email, "jo+123@public.com")
+        creator.reload
+      end
+
+      it "sets the state to STOPPED" do
+        expect {
+          petition.stop!(dissolution_at)
+        }.to change {
+          petition.state
+        }.from(Petition::PENDING_STATE).to(Petition::STOPPED_STATE)
+      end
+
+      it "sets the stopped date to the dissolution time" do
+        expect {
+          petition.stop!(dissolution_at)
+        }.to change {
+          petition.stopped_at
+        }.from(nil).to(dissolution_at)
+      end
+    end
   end
 
   describe '#flag' do