Show category hierarchy in transaction picker (#3292)

app/components/DS/category_select.html.erb

@@ -80,13 +80,22 @@
           </button>
         <% end %>
 
-        <% categories.each do |category| %>
+        <% Category::Group.for(categories).each do |group| %>
           <%= render partial: "DS/category_select/option",
                      locals: {
-                       category: category,
-                       selected: category.id.to_s == selected_id,
+                       category: group.category,
+                       selected: group.category.id.to_s == selected_id,
                        view_helpers: helpers
                      } %>
+
+          <% group.subcategories.each do |category| %>
+            <%= render partial: "DS/category_select/option",
+                       locals: {
+                         category: category,
+                         selected: category.id.to_s == selected_id,
+                         view_helpers: helpers
+                       } %>
+          <% end %>
         <% end %>
 
         <button type="button"

app/views/DS/category_select/_option.html.erb

@@ -15,6 +15,14 @@
     <%= view_helpers.icon("check") %>
   </span>
 
+  <% if category.parent_id.present? %>
+    <span class="ml-2 shrink-0"
+          data-testid="category-select-subcategory-indicator"
+          style="color: <%= category.color %>">
+      <%= view_helpers.icon("corner-down-right", size: "sm", color: "current") %>
+    </span>
+  <% end %>
+
   <span data-category-select-badge>
     <%= view_helpers.render partial: "categories/badge",
                        	    formats: [ :html ],

test/controllers/transactions_controller_test.rb

@@ -748,6 +748,11 @@ end
     assert_not_nil parent_index
     assert_not_nil child_index
     assert_equal parent_index + 1, child_index
+
+    child_option = wrapper.at_css("[data-category-id='#{categories(:subcategory).id}']")
+    assert_not_nil child_option, "expected the subcategory option to render"
+    assert child_option.at_css("[data-testid='category-select-subcategory-indicator']"),
+           "expected the subcategory option to show the hierarchy indicator used in Settings"
   end
 
   test "new renders a search box for account selection" do