Add .from_variant to the products/stock component

admin/app/components/solidus_admin/products/stock/component.rb

@@ -8,6 +8,13 @@ def self.from_product(product)
     )
   end
 
+  def self.from_variant(variant)
+    new(
+      on_hand: variant.total_on_hand,
+      variants_count: nil,
+    )
+  end
+
   def initialize(on_hand:, variants_count:)
     @on_hand = on_hand
     @variants_count = variants_count
@@ -24,7 +31,7 @@ def call
         tag.span t('.stock.in_stock', on_hand: @on_hand), class: 'text-red-500'
       end
 
-    variant_info = t('.for_variants', count: @variants_count)
+    variant_info = t('.for_variants', count: @variants_count) if @variants_count
 
     tag.span safe_join([stock_info, variant_info], ' ')
   end

admin/spec/components/solidus_admin/products/stock/component_spec.rb

@@ -6,4 +6,30 @@
   it "renders the overview preview" do
     render_preview(:overview)
   end
+
+  describe ".from_variant" do
+    it "has an empty variants count" do
+      allow(described_class).to receive(:new)
+
+      described_class.from_variant(instance_double(Spree::Variant, total_on_hand: 123))
+
+      expect(described_class).to have_received(:new).with(
+        on_hand: 123,
+        variants_count: nil,
+      )
+    end
+  end
+
+  describe ".from_product" do
+    it "has an empty variants count" do
+      allow(described_class).to receive(:new)
+
+      described_class.from_product(instance_double(Spree::Product, total_on_hand: 123, variants: []))
+
+      expect(described_class).to have_received(:new).with(
+        on_hand: 123,
+        variants_count: 0,
+      )
+    end
+  end
 end