Handle both types of redirection

One is based on the order step itself, the other is based on the current step passed through the params

app/controllers/split_checkout_controller.rb

@@ -17,7 +17,7 @@ class SplitCheckoutController < ::BaseController
   helper OrderHelper
 
   def edit
-    redirect_to_step unless params[:step]
+    redirect_to_step_based_on_order unless params[:step]
   end
 
   def update
@@ -116,7 +116,7 @@ class SplitCheckoutController < ::BaseController
     @order_params ||= Checkout::Params.new(@order, params, spree_current_user).call
   end
 
-  def redirect_to_step
+  def redirect_to_step_based_on_order
     case @order.state
     when "cart", "address", "delivery"
       redirect_to checkout_step_path(:details)
@@ -128,4 +128,14 @@ class SplitCheckoutController < ::BaseController
       redirect_to order_path(@order)
     end
   end
+
+  def redirect_to_step
+    case params[:step]
+    when "details"
+      return redirect_to checkout_step_path(:payment)
+    when "payment"
+      return redirect_to checkout_step_path(:summary)
+    end
+    redirect_to_step_based_on_order
+  end
 end

spec/system/consumer/split_checkout_spec.rb

@@ -425,6 +425,26 @@ describe "As a consumer, I want to checkout my order", js: true do
           end
         end
       end
+
+      context "handle the navigation when the order is ready for confirmation" do
+        it "redirect to summary step" do
+          visit "/checkout"
+
+          expect(page).to have_current_path checkout_step_path(:summary)
+        end
+
+        it "handle the navigation between each step by clicking on tab or button to submit the form" do
+          visit checkout_step_path(:summary)
+
+          click_on "Your details"
+
+          expect(page).to have_current_path checkout_step_path(:details)
+
+          click_on "Next - Payment method"
+
+          expect(page).to have_current_path checkout_step_path(:payment)
+        end
+      end
     end
   end