FIX: Don’t run validations when invalidating invites

This patch is a followup of
https://github.com/discourse/discourse/pull/21504 where limits on custom
message for an invite were introduced.

This had a side effect of making some existing invites invalid and with
the current code, they can’t be invalidated anymore.

This patch takes the approach of skipping the validations when invites
are invalidated since the important thing here is to mark the invite as
invalidated regardless of its actual state in the DB. (no other
attributes are updated at the same time anyway)

app/models/invite.rb

@@ -274,10 +274,12 @@ class Invite < ActiveRecord::Base
   end
 
   def self.invalidate_for_email(email)
-    invite = Invite.find_by(email: Email.downcase(email))
-    invite.update!(invalidated_at: Time.zone.now) if invite
+    Invite.find_by(email: Email.downcase(email))&.invalidate!
+  end
 
-    invite
+  def invalidate!
+    update_attribute(:invalidated_at, Time.current)
+    self
   end
 
   def resend_invite

spec/models/invite_spec.rb

@@ -478,7 +478,7 @@ RSpec.describe Invite do
     end
   end
 
-  describe "#invalidate_for_email" do
+  describe ".invalidate_for_email" do
     it "returns nil if there is no invite for the given email" do
       invite = Invite.invalidate_for_email("test@example.com")
       expect(invite).to eq(nil)
@@ -600,4 +600,29 @@ RSpec.describe Invite do
       end
     end
   end
+
+  describe "#invalidate!" do
+    subject(:invalidate) { invite.invalidate! }
+
+    fab!(:invite) { Fabricate(:invite) }
+
+    before { freeze_time }
+
+    it "invalidates the invite" do
+      expect { invalidate }.to change { invite.invalidated_at }.to Time.current
+    end
+
+    it "returns the invite" do
+      expect(invalidate).to eq invite
+    end
+
+    context "when the invite is in an invalid state" do
+      before { invite.update_attribute(:custom_message, "a" * 2000) }
+
+      it "still invalidates the invite" do
+        expect(invite).to be_invalid
+        expect { invalidate }.to change { invite.invalidated_at }.to Time.current
+      end
+    end
+  end
 end