Test deleting user without reassinging.

tests/phpunit/tests/user/countUserPosts.php

@@ -115,6 +115,20 @@ public function test_reassigning_users_posts_modifies_count() {
 		$this->assertSame( '4', count_user_posts( $new_user_id ), 'New user is expected to have a count of four posts following reassignment.' );
 	}
 
+	/**
+	 * Post count be correct after deleting user without reassigning posts.
+	 *
+	 * @ticket 39242
+	 */
+	public function test_post_count_retained_after_deleting_user_without_reassigning_posts() {
+		$this->assertSame( '4', count_user_posts( self::$user_id ), 'User is expected to have a count of four posts prior to deletion.' );
+
+		// Delete the original user without reassigning their posts.
+		wp_delete_user( self::$user_id );
+
+		$this->assertSame( '0', count_user_posts( self::$user_id ), 'User is expected to have a count of zero posts following deletion.' );
+	}
+
 	/**
 	 * Post count should work for users that don't exist but have posts assigned.
 	 *