Users: Ensure user counts remain accurate if users are added to or removed from the users table without corresponding usermeta entries being added or removed.

This has a slight performance impact on sites with a large number of users when the `time` strategy is used for counting users. Hopefully this impact will be negated by enhancements proposed in #38741.

Props psoluch, dots, boonebgorges, ptbello, tharsheblows

Fixes #29785


git-svn-id: https://develop.svn.wordpress.org/trunk@40560 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/user/countUsers.php

@@ -171,6 +171,31 @@ class Tests_User_CountUsers extends WP_UnitTestCase {
 
 	}
 
+	/**
+	 * @ticket 29785
+	 *
+	 * @dataProvider data_count_users_strategies
+	 */
+	public function test_count_users_should_not_count_users_who_are_not_in_posts_table( $strategy ) {
+		global $wpdb;
+
+		// Get a 'before' count for comparison.
+		$count = count_users( $strategy );
+
+		$u = self::factory()->user->create( array(
+			'role' => 'editor',
+		) );
+
+		// Manually delete the user, but leave the capabilities usermeta.
+		$wpdb->delete( $wpdb->users, array(
+			'ID' => $u,
+		) );
+
+		$count2 = count_users( $strategy );
+
+		$this->assertEqualSets( $count, $count2 );
+	}
+
 	function data_count_users_strategies() {
 		return array(
 			array(