fix(duplication): preserve empty table schemas

inc/duplication/data.php

@@ -154,10 +154,9 @@ public static function db_copy_tables($from_site_id, $to_site_id) {
 		 *
 		 * Runtime-only tables are skipped by default because queues, logs, caches,
 		 * analytics, and sessions are regenerated on the destination site. Empty
-		 * optional/custom tables are also skipped to avoid spending most of the
-		 * duplication time cloning schemas with no template data. WordPress core
-		 * content/config tables are always copied because wpmu_create_blog() creates
-		 * destination defaults that must be replaced with template values.
+		 * per-site tables are copied by default so plugins retain the complete schema
+		 * they expect on the destination. Installations can opt into skipping empty
+		 * optional tables through the dedicated filter.
 		 *
 		 * @since 2.5.1
 		 *
@@ -182,7 +181,7 @@ public static function should_copy_table($table, $table_base_name, $from_site_id
 			 *
 			 * Returning true forces a table to be copied; returning false skips it.
 			 * This preserves extension control over custom table duplication while
-			 * keeping the default path optimized for empty/runtime template tables.
+			 * keeping runtime table exclusions centralized.
 			 *
 			 * @since 2.5.1
 			 *
@@ -297,7 +296,7 @@ private static function skip_empty_tables($from_site_id, $to_site_id) {
 			 * @param int  $from_site_id      Source site ID.
 			 * @param int  $to_site_id        Target site ID.
 			 */
-			return (bool) apply_filters('wu_mucd_skip_empty_tables', true, $from_site_id, $to_site_id);
+			return (bool) apply_filters('wu_mucd_skip_empty_tables', false, $from_site_id, $to_site_id);
 		}
 
 		/**

tests/WP_Ultimo/Duplication/MUCD_Data_Test.php

@@ -90,12 +90,12 @@
 	 * Test try_replace with serialized array data.
 	 */
 	public function test_try_replace_serialized_array() {
 		$data = serialize(['url' => 'https://example.com/old-site/page']);
 		$row  = ['meta_value' => $data];
 
 		$result = \MUCD_Data::try_replace($row, 'meta_value', 'example.com/old-site', 'example.com/new-site');
 
 		$unserialized = unserialize($result);
 		$this->assertEquals('https://example.com/new-site/page', $unserialized['url']);
 	}
 
@@ -103,17 +103,17 @@
 	 * Test try_replace with nested serialized data.
 	 */
 	public function test_try_replace_nested_serialized_array() {
 		$data = serialize([
 			'settings' => [
 				'link' => 'https://example.com/old-site/about',
 				'icon' => 'fa-home',
 			],
 			'content'  => 'Visit https://example.com/old-site for more',
 		]);
 		$row  = ['meta_value' => $data];
 
 		$result       = \MUCD_Data::try_replace($row, 'meta_value', 'example.com/old-site', 'example.com/new-site');
 		$unserialized = unserialize($result);
 
 		$this->assertEquals('https://example.com/new-site/about', $unserialized['settings']['link']);
 		$this->assertEquals('Visit https://example.com/new-site for more', $unserialized['content']);
@@ -135,12 +135,12 @@
 	 * Test try_replace with double-serialized data.
 	 */
 	public function test_try_replace_double_serialized() {
 		$data = serialize(serialize(['url' => 'https://example.com/old-site/page']));
 		$row  = ['meta_value' => $data];
 
 		$result = \MUCD_Data::try_replace($row, 'meta_value', 'example.com/old-site', 'example.com/new-site');
 
 		$unserialized = unserialize(unserialize($result));
 		$this->assertEquals('https://example.com/new-site/page', $unserialized['url']);
 	}
 
@@ -642,18 +642,19 @@
 	}
 
 	/**
-	 * Test empty optional template tables are skipped by default.
+	 * Test empty optional template tables are copied by default.
 	 */
-	public function test_should_copy_table_skips_empty_optional_tables() {
+	public function test_should_copy_table_keeps_empty_optional_tables_by_default() {
 		global $wpdb;
 
-		$table = $wpdb->get_blog_prefix() . 'wu_empty_runtime_fixture';
+		$table_base_name = 'fc_wp_ultimo_test_subscriber_pivot';
+		$table           = $wpdb->get_blog_prefix() . $table_base_name;
 
 		$this->create_table_selection_fixture($table);
 
 		try {
-			$this->assertFalse(
-				\MUCD_Data::should_copy_table($table, 'wu_empty_runtime_fixture', get_current_blog_id(), 123)
+			$this->assertTrue(
+				\MUCD_Data::should_copy_table($table, $table_base_name, get_current_blog_id(), 123)
 			);
 		} finally {
 			$this->drop_table_selection_fixture($table);
@@ -695,6 +696,30 @@
 		);
 	}
 
+	/**
+	 * Test installations can opt into skipping empty optional tables.
+	 */
+	public function test_should_copy_table_can_skip_empty_optional_tables_when_enabled() {
+		global $wpdb;
+
+		$table  = $wpdb->get_blog_prefix() . 'wu_empty_runtime_fixture';
+		$filter = static function () {
+			return true;
+		};
+
+		$this->create_table_selection_fixture($table);
+		add_filter('wu_mucd_skip_empty_tables', $filter, 10, 3);
+
+		try {
+			$this->assertFalse(
+				\MUCD_Data::should_copy_table($table, 'wu_empty_runtime_fixture', get_current_blog_id(), 123)
+			);
+		} finally {
+			remove_filter('wu_mucd_skip_empty_tables', $filter, 10);
+			$this->drop_table_selection_fixture($table);
+		}
+	}
+
 	/**
 	 * Test filters can force-copy a table skipped by default.
 	 */
@@ -752,7 +777,8 @@
 
 		$this->drop_table_selection_fixture($table);
 
-		$wpdb->query( // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Test fixture table name cannot be bound.
+		$wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Test fixture table name cannot be bound.
+			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Test fixture table name cannot be bound.
 			"CREATE TABLE `{$table}` (id bigint(20) unsigned NOT NULL AUTO_INCREMENT, value varchar(20) NOT NULL DEFAULT '', PRIMARY KEY  (id))"
 		);
 	}