Render a dropdown list when an inclusion validator is used

app/helpers/maintenance_tasks/tasks_helper.rb

@@ -101,8 +101,17 @@ def csv_file_download_path(run)
       )
     end
 
-    # Return the appropriate field tag for the parameter
+    # Return the appropriate field tag for the parameter, based on its type.
+    # If the parameter has a `validates_inclusion_of` validator, return a dropdown list of options instead.
     def parameter_field(form_builder, parameter_name)
+      inclusion_validator = form_builder.object.class.validators_on(parameter_name).find do |validator|
+        validator.kind == :inclusion
+      end
+
+      return form_builder.select(
+        parameter_name, inclusion_validator.options[:in], prompt: "Select a value"
+      ) if inclusion_validator
+
       case form_builder.object.class.attribute_types[parameter_name]
       when ActiveModel::Type::Integer
         form_builder.number_field(parameter_name)

test/dummy/app/tasks/maintenance/params_task.rb

@@ -17,6 +17,9 @@ class ParamsTask < MaintenanceTasks::Task
     attribute :date_attr, :date
     attribute :time_attr, :time
     attribute :boolean_attr, :boolean
+    attribute :enum_attr, :integer
+
+    validates_inclusion_of :enum_attr, in: [100, 200, 300], allow_nil: true
 
     class << self
       attr_accessor :fast_task

test/models/maintenance_tasks/task_data_show_test.rb

@@ -87,6 +87,7 @@ class TaskDataShowTest < ActiveSupport::TestCase
           "date_attr",
           "time_attr",
           "boolean_attr",
+          "enum_attr",
         ],
         TaskDataShow.new("Maintenance::ParamsTask").parameter_names,
       )

test/system/maintenance_tasks/tasks_test.rb

@@ -114,6 +114,10 @@ class TasksTest < ApplicationSystemTestCase
       boolean_field = page.find_field("task[boolean_attr]")
       assert_equal("input", boolean_field.tag_name)
       assert_equal("checkbox", boolean_field[:type])
+      enum_field = page.find_field("task[enum_attr]")
+      assert_equal("select", enum_field.tag_name)
+      enum_field_options = enum_field.find_all("option").map { |option| option[:value] }
+      assert_equal(["", "100", "200", "300"], enum_field_options)
     end
 
     test "view a Task with multiple pages of Runs" do