update variable's context before invoking its to_liquid

test/integration/context_test.rb

@@ -36,6 +36,24 @@ class Category
   end
 end
 
+class ProductsDrop < Liquid::Drop
+  def initialize(products)
+    @products = products
+  end
+
+  def size
+    @products.size
+  end
+
+  def to_liquid
+    if @context["forloop"]
+      @products.first(@context["forloop"].length)
+    else
+      @products
+    end
+  end
+end
+
 class CategoryDrop < Liquid::Drop
   attr_accessor :category, :context
 
@@ -635,6 +653,25 @@ class ContextTest < Minitest::Test
     assert_equal(:my_value, c.registers[:my_register])
   end
 
+  def test_variable_to_liquid_returns_contextual_drop
+    context = {
+      "products" => ProductsDrop.new(["A", "B", "C", "D", "E"]),
+    }
+
+    template = Liquid::Template.parse(<<~LIQUID)
+      {%- for i in (1..3) -%}
+        for_loop_products_count: {{ products | size }}
+      {% endfor %}
+
+      unscoped_products_count: {{ products | size }}
+    LIQUID
+
+    result = template.render(context)
+
+    assert_includes(result, "for_loop_products_count: 3")
+    assert_includes(result, "unscoped_products_count: 5")
+  end
+
   private
 
   def assert_no_object_allocations