From 9eab65e18ad9a9496b7d922ee2f2b192fbad7bf6 Mon Sep 17 00:00:00 2001
From: Mike Dalessio <mike.dalessio@gmail.com>
Date: Wed, 18 Aug 2021 18:53:04 -0400
Subject: [PATCH] test: repro for #2296

---
 test/xml/test_schema.rb | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test/xml/test_schema.rb b/test/xml/test_schema.rb
index 6cba39abe7..f09678b579 100644
--- a/test/xml/test_schema.rb
+++ b/test/xml/test_schema.rb
@@ -214,6 +214,21 @@ def test_xsd_with_dtd
         end
       end
 
+      def test_xsd_import_with_no_systemid
+        # https://github.com/sparklemotion/nokogiri/pull/2296
+        xsd = <<~EOF
+          <?xml version="1.0" encoding="UTF-8"?>
+          <xs:schema
+            xmlns:xs="http://www.w3.org/2001/XMLSchema"
+            xmlns="http://www.w3.org/1998/Math/MathML"
+            targetNamespace="http://www.w3.org/1998/Math/MathML"
+          >
+          <xs:import/>
+          </xs:schema>
+        EOF
+        Nokogiri::XML::Schema(xsd) # assert_nothing_raised
+      end
+
       describe "CVE-2020-26247" do
         # https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-vr8q-g5c7-m54m
         let(:schema) do