Upgrade old StripeConnect payment methods to SCA

StripeConnect has been replaced by StripeSCA. But we still have some
StripeConnect payment methods in our production databases. We need to
convert them to StripeSCA methods before we can remove the related
code and clean up. Otherwise our code would raise errors when
encountering an old StripeConnect method, not knowing what that is.

db/migrate/20220118053107_convert_stripe_connect_to_stripe_sca.rb

@@ -0,0 +1,57 @@
+class ConvertStripeConnectToStripeSca < ActiveRecord::Migration[6.1]
+  class SpreePreference < ActiveRecord::Base
+    scope :leftover_from_payment_type, ->(class_name) {
+      joins <<~SQL
+         JOIN spree_payment_methods
+           ON spree_preferences.key =
+              CONCAT('/#{class_name.underscore}/enterprise_id/', spree_payment_methods.id)
+          AND spree_payment_methods.type != '#{class_name}'
+      SQL
+    }
+  end
+
+  def up
+    delete_outdated_spree_preferences
+    upgrade_stripe_payment_methods
+    update_payment_method_preferences
+  end
+
+  private
+
+  # When changing the type of a payment method, we leave orphaned records in
+  # the spree_preferences table. The key of the preference contains the type
+  # of the payment method and therefore changing the type disconnects the
+  # preference.
+  #
+  # Here we delete orphaned preferences first so that we don't have any
+  # conflicts later when updating preferences alongside the connected
+  # payment methods.
+  def delete_outdated_spree_preferences
+    outdated_keys =
+      SpreePreference.leftover_from_payment_type("Spree::Gateway::StripeConnect").pluck(:key) +
+      SpreePreference.leftover_from_payment_type("Spree::Gateway::StripeSCA").pluck(:key)
+
+    SpreePreference.where(key: outdated_keys).delete_all
+
+    # Spree preferences are cached and we want to avoid reading old values.
+    # Danger: The cache may alter the given array in place. Make sure to
+    # not use the `outdated_keys` variable after this call.
+    Rails.cache.delete_multi(outdated_keys)
+  end
+
+  def upgrade_stripe_payment_methods
+    execute <<~SQL
+      UPDATE spree_payment_methods
+        SET type = 'Spree::Gateway::StripeSCA'
+      WHERE type = 'Spree::Gateway::StripeConnect'
+    SQL
+  end
+
+  def update_payment_method_preferences
+    execute <<~SQL
+      UPDATE spree_preferences
+         SET key = replace(key, 'stripe_connect', 'stripe_sca')
+       WHERE key LIKE '/spree/gateway/stripe_connect/%'
+    SQL
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_01_14_110920) do
+ActiveRecord::Schema.define(version: 2022_01_18_053107) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

spec/migrations/convert_stripe_connect_to_stripe_sca_spec.rb

@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require_relative '../../db/migrate/20220118053107_convert_stripe_connect_to_stripe_sca'
+
+describe ConvertStripeConnectToStripeSca do
+  let(:owner) { create(:distributor_enterprise) }
+  let(:new_owner) { create(:distributor_enterprise) }
+  let(:old_stripe_connect) {
+    Spree::Gateway::StripeConnect.create!(
+      name: "Stripe",
+      environment: "test",
+      preferred_enterprise_id: owner.id,
+      distributor_ids: [owner.id]
+    )
+  }
+  let(:result) { Spree::PaymentMethod.find(old_stripe_connect.id) }
+
+  before do
+    # Activate the cache because it's deactivated in test environment.
+    allow(Spree::Preferences::Store.instance).to receive(:should_persist?).and_return(true)
+
+    # Create the payment method after cache activation to store the owner.
+    old_stripe_connect
+  end
+
+  it "converts payment methods" do
+    subject.up
+
+    expect(result.class).to eq Spree::Gateway::StripeSCA
+  end
+
+  it "keeps attributes" do
+    subject.up
+
+    expect(result.name).to eq "Stripe"
+    expect(result.environment).to eq "test"
+    expect(result.distributor_ids).to eq [owner.id]
+  end
+
+  it "keeps Spree preferences" do
+    subject.up
+
+    expect(result.preferred_enterprise_id).to eq owner.id
+  end
+
+  it "doesn't move outdated StripeConnect preferences to StripeSCA methods" do
+    # When you change the type of a payment method in the admin screen
+    # it leaves old entries in the spree_preferences table.
+    # Here is a simulation of such a change:
+    old_stripe_connect.update_columns(type: "Spree::Gateway::StripeSCA")
+    changed_method = Spree::PaymentMethod.find(old_stripe_connect.id)
+    changed_method.preferred_enterprise_id = new_owner.id
+
+    subject.up
+
+    expect(result.preferred_enterprise_id).to eq new_owner.id
+  end
+
+  it "keeps Spree preferences despite conflicting preference keys" do
+    # We change the payment method to StripeSCA and then back to StripeConnect
+    # to generate a conflicting preference. We want to keep the preference
+    # of the current payment method, not the intermediately changed one.
+    old_stripe_connect.update_columns(type: "Spree::Gateway::StripeSCA")
+    changed_method = Spree::PaymentMethod.find(old_stripe_connect.id)
+    changed_method.preferred_enterprise_id = owner.id
+    old_stripe_connect.update_columns(type: "Spree::Gateway::StripeConnect")
+    old_stripe_connect.preferred_enterprise_id = new_owner.id
+
+    subject.up
+
+    expect(result.preferred_enterprise_id).to eq new_owner.id
+  end
+
+  it "doesn't mess with new Stripe payment methods" do
+    stripe = Spree::Gateway::StripeSCA.create!(
+      name: "Modern Stripe",
+      environment: "test",
+      preferred_enterprise_id: owner.id,
+      distributor_ids: [owner.id]
+    )
+
+    expect { subject.up }.to_not change { stripe.reload.attributes }
+  end
+
+  it "doesn't mess with other payment methods" do
+    cash = Spree::PaymentMethod::Check.create!(
+      name: "Cash on delivery",
+      environment: "test",
+      distributor_ids: [owner.id]
+    )
+
+    expect { subject.up }.to_not change { cash.reload.attributes }
+  end
+end