Adds retrieve payment methods customer endpoint

lib/stripe_mock/request_handlers/customers.rb

@@ -10,6 +10,7 @@ def Customers.included(klass)
         klass.add_handler 'get /v1/customers',                      :list_customers
         klass.add_handler 'get /v1/customers/search',               :search_customers
         klass.add_handler 'delete /v1/customers/([^/]*)/discount',  :delete_customer_discount
+        klass.add_handler 'get /v1/customers/([^/]+)/payment_methods/([^/]+)', :retrieve_payment_method
       end
 
       def new_customer(route, method_url, params, headers)
@@ -160,6 +161,29 @@ def delete_customer_discount(route, method_url, params, headers)
 
         cus
       end
+
+      def retrieve_payment_method(route, method_url, params, headers)
+        stripe_account = headers && headers[:stripe_account] || Stripe.api_key
+
+        route =~ method_url
+        customer_id, payment_method_id = $1, $2
+        customer = assert_existence(:customer, customer_id, customers[stripe_account][customer_id])
+        payment_method = payment_methods[payment_method_id]
+
+        if payment_method && payment_method[:customer] == customer_id
+          return payment_method
+        end
+
+        # If not found or not attached correctly, attempt to find in the customer's legacy sources.
+        if customer[:sources] && customer[:sources][:data]
+          source = customer[:sources][:data].detect { |src| src[:id] == payment_method_id }
+          if source && source[:customer] == customer_id
+            return source
+          end
+        end
+
+        raise Stripe::InvalidRequestError.new("Payment method #{payment_method_id} is not attached to customer #{customer_id}", :customer, http_status: 404)
+      end
     end
   end
 end

spec/shared_stripe_examples/customer_examples.rb

@@ -535,4 +535,38 @@ def gen_card_tk
     customer = Stripe::Customer.retrieve("test_customer_update")
     expect(customer.discount).to be nil
   end
+
+  it "retrieves a stripe customers payment method" do
+    payment_method = Stripe::PaymentMethod.create({
+      type: 'card',
+      card: {
+        number: '4242424242424242',
+        exp_month: 12,
+        exp_year: 2024,
+        cvc: 123
+      }
+    })
+
+    customer = Stripe::Customer.create({
+      email: 'johnny@appleseed.com',
+      description: "a description"
+    })
+
+    payment_method.attach(customer: customer.id)
+
+    retrieved_payment_method = Stripe::Customer.retrieve_payment_method(customer.id, payment_method.id)
+    expect(retrieved_payment_method.id).to eq(payment_method.id)
+  end
+
+  it "retrives a stripe customers payment method with a default card" do
+    customer = Stripe::Customer.create({
+      email: 'johnny@appleseed.com',
+      source: gen_card_tk,
+      description: "a description"
+    })
+
+    retrieved_payment_method = Stripe::Customer.retrieve_payment_method(customer.id, customer.sources.data.first.id)
+    expect(retrieved_payment_method.id).to eq(customer.sources.data.first.id)
+  end
+
 end