🥗✨Tobias: Payout#issue won't create Payment for new Beneficiary

This one actually needed adjusting! Turns out, `Payout#issue` would
happily create a new `Payment` for a new `Beneficiary`, which is less
than ideal.

Now we have a guard clause that will prevent `Payout#issue` from making
additional `Payments` when there are already `Payments` present.

app/furniture/tobias/payout.rb

@@ -9,6 +9,8 @@ class Payout < ApplicationRecord
     monetize :amount_cents
 
     def issue
+      return if payments.present?
+
       per_beneficiary_amount = (amount / beneficiaries.count)
       beneficiaries.each do |beneficiary|
         payments.create_with(amount: per_beneficiary_amount).find_or_create_by(beneficiary_id: beneficiary.id)

spec/tobias/payout_spec.rb

@@ -31,13 +31,19 @@
     end
 
     context "when running twice" do
-      it "does not issue multiple payouts" do
+      it "does not issue multiple payouts, even when beneficiaries are added" do
         payout = create(:tobias_payout, amount_cents: 100_00)
 
         create_list(:tobias_beneficiary, 2, trust: payout.trust)
 
         payout.issue
 
+        create(:tobias_beneficiary, trust: payout.trust)
+
+        # ActiveRecord appears to be caching the `payout.beneficiaries` results
+        # Reload busts that cache.
+        payout.reload
+
         expect { payout.issue }.not_to(change(payout.payments, :count))
       end
     end