Fixes DataTable empty-state heading order

Axe flagged a heading-order violation on the empty_state preview: the
table title renders as an h2 while the Blankslate heading was hard-coded
to h4, skipping a level.

Defaults the empty-state heading to h3 and exposes a heading_tag
parameter on the slot so callers embedding the table under deeper
heading structures can adjust the level.

Author: myabc

app/components/primer/open_project/data_table.rb

@@ -90,9 +90,10 @@ def sort_data
       # rows. Without this slot, an empty table renders a default
       # <%= link_to_component(Primer::OpenProject::DataTable::EmptyState) %>.
       # Ignored while rows are present.
-      renders_one :empty_state, ->(title:, description: nil, icon: nil, interactive: false, **system_arguments) {
+      renders_one :empty_state, ->(title:, heading_tag: EmptyState::HEADING_TAG_DEFAULT, description: nil, icon: nil, interactive: false, **system_arguments) {
         EmptyState.new(
           title: title,
+          heading_tag: heading_tag,
           description: description,
           icon: icon,
           interactive: interactive,

app/components/primer/open_project/data_table/empty_state.rb

@@ -12,7 +12,12 @@ class DataTable
       class EmptyState < Primer::Component
         status :open_project
 
+        HEADING_TAG_DEFAULT = :h3
+
         # @param title [String] Empty-state heading
+        # @param heading_tag [Symbol] Heading level of the empty-state title.
+        #   Defaults to `:h3` so it nests under the table's `:h2` title without
+        #   skipping a level.
         # @param description [String, nil] Optional supporting text
         # @param icon [Symbol, nil] Optional Primer icon
         # @param interactive [Boolean] Whether empty-state updates should be
@@ -21,12 +26,14 @@ class EmptyState < Primer::Component
         #   System arguments passed to the underlying `Primer::Beta::Blankslate`
         def initialize(
           title:,
+          heading_tag: HEADING_TAG_DEFAULT,
           description: nil,
           icon: nil,
           interactive: false,
           **system_arguments
         )
           @title = title
+          @heading_tag = heading_tag
           @description = description
           @icon = icon
 
@@ -50,7 +57,9 @@ def call
 
         def blankslate
           blankslate = Primer::Beta::Blankslate.new(**@system_arguments)
-          blankslate.with_heading(tag: :h4).with_content(@title)
+          # `Primer::Beta::Blankslate` validates the tag against its own
+          # heading options.
+          blankslate.with_heading(tag: @heading_tag).with_content(@title)
           blankslate.with_description_content(@description) if @description
           blankslate.with_visual_icon(icon: @icon) if @icon
 

static/arguments.json

@@ -6238,6 +6238,12 @@
         "default": "N/A",
         "description": "Empty-state heading"
       },
+      {
+        "name": "heading_tag",
+        "type": "Symbol",
+        "default": "`:h3`",
+        "description": "Heading level of the empty-state title. Defaults to `:h3` so it nests under the table's `:h2` title without skipping a level."
+      },
       {
         "name": "description",
         "type": "String, nil",

static/constants.json

@@ -1807,7 +1807,8 @@
     "GeneratedSlotMethods": "Primer::OpenProject::DataTable::Column::GeneratedSlotMethods"
   },
   "Primer::OpenProject::DataTable::EmptyState": {
-    "GeneratedSlotMethods": "Primer::OpenProject::DataTable::EmptyState::GeneratedSlotMethods"
+    "GeneratedSlotMethods": "Primer::OpenProject::DataTable::EmptyState::GeneratedSlotMethods",
+    "HEADING_TAG_DEFAULT": "h3"
   },
   "Primer::OpenProject::DataTable::PaginationFooter": {
     "GeneratedSlotMethods": "Primer::OpenProject::DataTable::PaginationFooter::GeneratedSlotMethods"

static/info_arch.json

@@ -20420,6 +20420,12 @@
         "default": "N/A",
         "description": "Empty-state heading"
       },
+      {
+        "name": "heading_tag",
+        "type": "Symbol",
+        "default": "`:h3`",
+        "description": "Heading level of the empty-state title. Defaults to `:h3` so it nests under the table's `:h2` title without skipping a level."
+      },
       {
         "name": "description",
         "type": "String, nil",

test/components/primer/open_project/data_table/data_table_test.rb

@@ -592,7 +592,7 @@ def test_renders_default_empty_state_without_rows
       data_table.with_title { "Projects" }
     end
 
-    assert_selector(".TableContainer .TableEmptyState .blankslate h4", text: "No data available")
+    assert_selector(".TableContainer .TableEmptyState .blankslate h3", text: "No data available")
     assert_no_selector("table")
     assert_no_selector("[aria-labelledby]")
   end
@@ -607,11 +607,20 @@ def test_renders_custom_empty_state_without_rows
       )
     end
 
-    assert_selector(".TableEmptyState h4", text: "Nothing here")
+    assert_selector(".TableEmptyState h3", text: "Nothing here")
     assert_selector(".TableEmptyState p", text: "Create a project to get started.")
     assert_selector(".TableEmptyState .octicon-book")
   end
 
+  def test_renders_empty_state_with_custom_heading_tag
+    render_component([]) do |data_table|
+      data_table.with_column(field: :subject, header: "Subject")
+      data_table.with_empty_state(title: "Nothing here", heading_tag: :h4)
+    end
+
+    assert_selector(".TableEmptyState h4", text: "Nothing here")
+  end
+
   def test_interactive_empty_state_announces_politely
     render_component([]) do |data_table|
       data_table.with_column(field: :subject, header: "Subject")