Adopt 'undef context='

lib/liquid/self_drop.rb

@@ -31,10 +31,10 @@ module Liquid
       @self_context.variable_defined?(key)
     end
 
-    undef context
-
     def to_liquid
       self
     end
+
+    undef context=
   end
 end

lib/liquid/template.rb

@@ -151,8 +151,10 @@ module Liquid
 
         c
       when Liquid::Drop
-        drop         = args.shift
-        drop.context = Context.new([drop, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits, {}, @environment)
+        drop = args.shift
+        c    = Context.new([drop, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits, {}, @environment)
+        drop.context = c if drop.respond_to?(:context=)
+        c
       when Hash
         Context.new([args.shift, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits, {}, @environment)
       when nil

test/integration/self_drop_context_test.rb

@@ -69,12 +69,12 @@ class SelfDropContextTest < Minitest::Test
     assert_template_result('42', source)
   end
 
-  def test_self_drop_context_writer_is_a_noop
+  def test_self_drop_context_setter_is_undefined
     context = Context.new
     drop = SelfDrop.new(context)
-    assert(drop.respond_to?(:context=))
-    drop.context = Context.new
-    assert_nil(drop.instance_variable_get(:@context))
+    refute(drop.respond_to?(:context=))
+
+    assert_template_result('42', '{{ self.x }}', { 'x' => 42 })
   end
 
   def test_self_drop_with_strict_variables_does_not_raise_for_defined_var
@@ -88,4 +88,11 @@ class SelfDropContextTest < Minitest::Test
     result = t.render({}, strict_variables: true)
     assert_equal('', result)
   end
+
+  def test_self_drop_can_be_passed_as_bare_drop_to_render
+    t = Template.parse('{{ self.x }}')
+    drop = SelfDrop.new(Context.new({ 'x' => 42 }))
+    result = t.render(drop)
+    assert_equal('42', result)
+  end
 end