diff --git a/rails_application/app/views/products/index.html.erb b/rails_application/app/views/products/index.html.erb
index dfa14fea..65f3ec27 100644
--- a/rails_application/app/views/products/index.html.erb
+++ b/rails_application/app/views/products/index.html.erb
@@ -20,7 +20,7 @@
 
   <tbody>
   <% @products.each do |product| %>
-    <tr class="border-t">
+    <tr class="border-t" id=<%= dom_id(product) %>>
       <td class="py-2"><%= link_to product.name, product_path(product), class: "hover:underline text-blue-500" %></td>
       <td class="py-2"><%= number_to_currency product.price %></td>
       <td class="py-2"><%= product.vat_rate %></td>
diff --git a/rails_application/test/integration/supplies_test.rb b/rails_application/test/integration/supplies_test.rb
new file mode 100644
index 00000000..5ab6fd68
--- /dev/null
+++ b/rails_application/test/integration/supplies_test.rb
@@ -0,0 +1,50 @@
+require "test_helper"
+
+class SuppliesTest < InMemoryRESIntegrationTestCase
+  def setup
+    super
+  end
+
+  def test_supply_new_product
+    create_product
+    product = Product.find_by(sku:)
+    increase_stock_level_by_10(product.id)
+
+    follow_redirect!
+
+    assert_select "tr#product_#{product.id}" do
+      assert_select "td", "10"
+    end
+    assert_equal(10, product.reload.stock_level)
+  end
+
+  def test_supply_product_with_existing_stock
+    create_product
+    product = Product.find_by(sku:)
+    increase_stock_level_by_10(product.id)
+
+    assert_changes -> { Product.find(product.id).stock_level }, from: 10, to: 20 do
+      increase_stock_level_by_10(product.id)
+    end
+
+    follow_redirect!
+
+    assert_select "tr#product_#{product.id}" do
+      assert_select "td", "20"
+    end
+  end
+
+  private
+
+  def increase_stock_level_by_10(product_id)
+    post "/products/#{product_id}/supplies", params: { product_id: product_id, quantity: 10 }
+  end
+
+  def create_product
+    post "/products", params: { product: { name: "Stanley Cup", price: 100, vat_rate: 23, sku: } }
+  end
+
+  def sku
+    "SKU-ST4NL3Y"
+  end
+end