Emit warning if keyword arguments passed to default plugin

lib/mobility/plugins/default.rb

@@ -71,6 +71,11 @@ def initialize(default_option)
           default = options.has_key?(:default) ? options.delete(:default) : default_option
           if (value = super(locale, options)).nil?
             return default unless default.is_a?(Proc)
+            # TODO: Remove in v1.0
+            if default.parameters.any? { |n, v| [:keyreq, :keyopt].include?(n) && [:model, :attribute, :locale, :options].include?(v) }
+              warn "WARNING: The Mobility default plugin no longer accepts keyword arguments."
+              return value
+            end
             args = [attribute, locale, options]
             args = args.first(default.arity) unless default.arity < 0
             model.instance_exec(*args, &default)

spec/mobility/plugins/default_spec.rb

@@ -87,6 +87,15 @@
             expect(backend.read(:fr, default: default_as_option, this: 'option')).to eq("default title")
           end
         end
+
+        # TODO: Remove in v1.0
+        it "emits warning if proc takes keyword arguments" do
+          expect(backend_double).to receive(:read).once.with(:fr, this: 'option').and_return(nil)
+          default_as_option = Proc.new { |model:, attribute:, locale:, options:| }
+          expect {
+            backend.read(:fr, default: default_as_option, this: 'option')
+          }.to output(/#{"WARNING: The Mobility default plugin no longer accepts keyword arguments."}/).to_stderr
+        end
       end
     end
   end