Disallow creating Stripe payments on the admin panel

app/models/solidus_stripe/payment_method.rb

@@ -5,6 +5,8 @@ class PaymentMethod < ::Spree::PaymentMethod
     preference :api_key, :string
     preference :publishable_key, :string
 
+    validates :available_to_admin, inclusion: { in: [false] }
+
     def partial_name
       "stripe"
     end

config/locales/en.yml

@@ -8,3 +8,9 @@ en:
     models:
       solidus_stripe/payment_source: Solidus Stripe Payment Source
       solidus_stripe/payment_method: Solidus Stripe Payment Method
+    errors:
+      models:
+        solidus_stripe/payment_method:
+          attributes:
+            available_to_admin:
+              inclusion: "is not allowed for the Stripe payment method"

lib/solidus_stripe/testing_support/factories.rb

@@ -4,6 +4,7 @@
   factory :stripe_payment_method, class: 'SolidusStripe::PaymentMethod' do
     type { "SolidusStripe::PaymentMethod" }
     name { "Stripe Payment Method" }
+    available_to_admin { false }
     preferences {
       {
         api_key: SecureRandom.hex(8),

spec/models/solidus_stripe/payment_method_spec.rb

@@ -6,4 +6,14 @@
   it 'has a working factory' do
     expect(create(:stripe_payment_method)).to be_valid
   end
+
+  it "doesn't allow available_to_admin" do
+    record = described_class.new(available_to_admin: true)
+
+    record.valid?
+
+    expect(
+      record.errors.added?(:available_to_admin, :inclusion, value: true)
+    ).to be(true)
+  end
 end