Add Email Topic subscription list to filtered content Email Alert option

app/components/email_alert_fieldset_component.rb

@@ -4,19 +4,17 @@ def initialize(email_alert:)
   end
 
   def render_all_content_condition_inputs
-    hidden_signup_content_id_input = hidden_signup_content_id_input("all_content_signup_id")
-
-    # Do not render the title prefix input if the value is a hash because we don't want to override the existing the existing
-    # values in such cases. We are going to revisit this later, but for now we only allow users to override this setting
-    # for finders with a single string value. Trello card for future work: https://trello.com/c/Qe8wOpaw
-    return hidden_signup_content_id_input if @email_alert.list_title_prefix.is_a?(Hash)
-
-    email_topic_list_title_prefix("all_content_list_title_prefix") + hidden_signup_content_id_input
+    [
+      render_hidden_signup_content_id_input("all_content_signup_id"),
+      render_email_topic_list_title_prefix("all_content_list_title_prefix"),
+    ].compact.join.html_safe
   end
 
   # We are handling changes to email facet filters offline at present.
   def render_filtered_content_condition_inputs
-    hidden_signup_content_id_input("filtered_content_signup_id") +
+    [
+      render_hidden_signup_content_id_input("filtered_content_signup_id"),
+      render_email_topic_list_title_prefix("filtered_content_list_title_prefix"),
       render("govuk_publishing_components/components/checkboxes", {
         name: "email_filter_by",
         heading: "Selected filter: #{@email_alert.filter&.humanize}",
@@ -26,7 +24,8 @@ def render_filtered_content_condition_inputs
             value: "CHANGE_REQUESTED",
           },
         ],
-      })
+      }),
+    ].compact.join.html_safe
   end
 
   def render_external_condition_inputs
@@ -42,7 +41,12 @@ def render_external_condition_inputs
 
 private
 
-  def email_topic_list_title_prefix(input_name)
+  def render_email_topic_list_title_prefix(input_name)
+    # Do not render the title prefix input if the value is a hash because we don't want to override the existing the existing
+    # values in such cases. We are going to revisit this later, but for now we only allow users to override this setting
+    # for finders with a single string value. Trello card for future work: https://trello.com/c/Qe8wOpaw
+    return if @email_alert.list_title_prefix.is_a?(Hash)
+
     render("govuk_publishing_components/components/input", {
       label: {
         text: "Email subscription topic",
@@ -52,7 +56,7 @@ def email_topic_list_title_prefix(input_name)
     })
   end
 
-  def hidden_signup_content_id_input(input_name)
+  def render_hidden_signup_content_id_input(input_name)
     render("govuk_publishing_components/components/input", {
       type: "hidden",
       name: input_name,

spec/components/email_alert_fieldset_component_spec.rb

@@ -91,4 +91,26 @@
     expect(page).to have_checked_field("email_alert_type", with: "filtered_content")
     expect(page).to have_field("filtered_content_signup_id", with: "new-id", type: "hidden")
   end
+
+  it "renders the email subscription topic if the filtered_content value is checked" do
+    email_alert = EmailAlert.new
+    email_alert.type = :filtered_content
+    email_alert.list_title_prefix = "Finder email subscription"
+    render_inline(described_class.new(email_alert:))
+
+    expect(page).to have_text("Email subscription topic")
+    expect(page).to have_field("filtered_content_list_title_prefix", with: email_alert.list_title_prefix)
+  end
+
+  # We do not render the title prefix input if the value is a hash because we don't want to override the existing the existing
+  # values in such cases. We are going to revisit this later. Trello card for future work: https://trello.com/c/Qe8wOpaw
+  it "does not render the email subscription topic if the filtered_content value is checked but the current topic value is a hash" do
+    email_alert = EmailAlert.new
+    email_alert.type = :filtered_content
+    email_alert.list_title_prefix = {}
+    render_inline(described_class.new(email_alert:))
+
+    expect(page).not_to have_text("Email subscription topic")
+    expect(page).not_to have_field("filtered_content_list_title_prefix", with: email_alert.list_title_prefix)
+  end
 end