always cast select_options to an array (#3872)

Always cast select_options to an array so that upper layers can call
.first and .second safely on them.

apps/dashboard/app/lib/smart_attributes/attribute.rb

@@ -174,6 +174,14 @@ def select_choices(hide_excludable: true)
         else
           false
         end
+      end.map do |entry|
+        # always cast to array so other layers can try .first & .second for labels and values.
+        # and let nils fall through and get caught in validate!
+        if entry.is_a?(Array)
+          entry
+        elsif entry.is_a?(String) || entry.is_a?(Symbol)
+          [entry.to_s, entry.to_s]
+        end
       end
     end
 

apps/dashboard/test/system/batch_connect_widgets_test.rb

@@ -243,4 +243,43 @@ def make_bc_app(dir, form)
       assert(find("##{bc_ele_id('aa_b_cc')}").visible?)
     end
   end
+
+  test 'radio_buttons accept scalar and array options' do
+    Dir.mktmpdir do |dir|
+      form = <<~HEREDOC
+        ---
+        cluster:
+          - owens
+        form:
+          - scalar
+          - vector
+        attributes:
+          scalar:
+            widget: radio_button
+            options:
+              - one
+              - two
+          vector:
+            widget: radio_button
+            options:
+              - [Three, three]
+              - [Four, four]
+      HEREDOC
+
+      make_bc_app(dir, form)
+      visit new_batch_connect_session_context_url('sys/app')
+
+      # values are all lowercase
+      assert_equal('one', find("##{bc_ele_id('scalar_one')}").value)
+      assert_equal('two', find("##{bc_ele_id('scalar_two')}").value)
+      assert_equal('three', find("##{bc_ele_id('vector_three')}").value)
+      assert_equal('four', find("##{bc_ele_id('vector_four')}").value)
+
+      # one and two's labels are lowercase, but Three and Four have uppercase labels.
+      assert_equal('one', find("[for='#{bc_ele_id('scalar_one')}']").text)
+      assert_equal('two', find("[for='#{bc_ele_id('scalar_two')}']").text)
+      assert_equal('Three', find("[for='#{bc_ele_id('vector_three')}']").text)
+      assert_equal('Four', find("[for='#{bc_ele_id('vector_four')}']").text)
+    end
+  end
 end