diff --git a/tests/lib/SimpleSAML/Utils/XMLTest.php b/tests/lib/SimpleSAML/Utils/XMLTest.php
index 938f4ef38587fc8fe4751e8876ec5457621d2211..55fda70bac4d54666b9972d4c1d09533c7bf3387 100644
--- a/tests/lib/SimpleSAML/Utils/XMLTest.php
+++ b/tests/lib/SimpleSAML/Utils/XMLTest.php
@@ -389,35 +389,47 @@ NOWDOC;
 
     /**
      * @covers \SimpleSAML\Utils\XML::isValid
-     * @test
      * @return void
      */
     public function testIsValidMetadata()
     {
-        Configuration::loadFromArray([], '[ARRAY]', 'simplesaml');
-
         $schema = 'saml-schema-metadata-2.0.xsd';
 
-        $dom = $this->getMockBuilder('\DOMDocument')
-            ->setMethods(['schemaValidate'])
-            ->disableOriginalConstructor()
-            ->getMock();
-
-        /*
-         * Unfortunately, we cannot actually test schemaValidate. To
-         * effectively unit test this function we'd have to enable LIBXML_NONET
-         * which disables network access when loading documents. PHP does not
-         * currently support enabling this flag.
-         */
-        $dom->method('schemaValidate')
-            ->willReturn(true);
-
+        $xml = <<<'XMLDOC'
+<?xml version="1.0"?>
+<md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" entityID="https://idp.example.org/saml2/idp/metadata.php" ID="_e3369c45cf941d5ace90fbf936604c2409fd8bf1ca9bec5607c30e18169fd73d"><ds:Signature>
+  <ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+    <ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
+  <ds:Reference URI="#_e3369c45cf941d5ace90fbf936604c2409fd8bf1ca9bec5607c30e18169fd73d"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>dM5kF0HTkW9fnJOS77yNgTAwBj4=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>i5u6pKkDLYEX9KAV7Z0dd/jEgJ6KoOePF2NcrkIcz492OxDImS9il43Y0W3KRZPdq9fq6BQKzNifPhCN8wk8VhoceM/1Am3Nxv8d6hx+1IOeVmJT5kBMcRO8GFee6CnbwtsMH1TkU37vXt7isf237Pzi2hxDCVaKOPbNmm6lTS8=</ds:SignatureValue>
+<ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></ds:KeyInfo></ds:Signature>
+  <md:IDPSSODescriptor protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol">
+    <md:KeyDescriptor use="signing">
+      <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+        <ds:X509Data>
+          <ds:X509Certificate>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</ds:X509Certificate>
+        </ds:X509Data>
+      </ds:KeyInfo>
+    </md:KeyDescriptor>
+    <md:KeyDescriptor use="encryption">
+      <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+        <ds:X509Data>
+          <ds:X509Certificate>MIIGHzCCBAegAwIBAgIBAzANBgkqhkiG9w0BAQsFADCBiTELMAkGA1UEBhMCTkwxFTATBgNVBAgTDFp1aWQtSG9sbGFuZDESMBAGA1UEBxMJUGlqbmFja2VyMRQwEgYDVQQKEwtNT08tQXJjaGl2ZTEgMB4GCSqGSIb3DQEJARYRdHZkaWplbkBnbWFpbC5jb20xFzAVBgNVBAMTDk1PTy1BcmNoaXZlLm5sMB4XDTE3MDYyOTEzNTcxMFoXDTI3MDYyNzEzNTcxMFowgZUxCzAJBgNVBAYTAk5MMRUwEwYDVQQIEwxadWlkLUhvbGxhbmQxEjAQBgNVBAcTCVBpam5hY2tlcjEUMBIGA1UEChMLTU9PLUFyY2hpdmUxIDAeBgkqhkiG9w0BCQEWEXR2ZGlqZW5AZ21haWwuY29tMSMwIQYDVQQDExpzaWduaW5nLmlkcC5tb28tYXJjaGl2ZS5ubDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAKw8a1UbecDb9297f4RD3gDB1CG+Lzlz771u6wv+gGH3slSzV3VsCoARtAXjJExl8RJWRzD1J39UwLnalEyOklD/5tBT9oWMLppCFX4d1O0oszj5DUs9KIEYJ6pPB7ddqGTk/1q8nwlwKsrMIXFJ3yZOAybVPE33najzpMSKqXq23OuyXs6F/AQ1WxQdpCGeI408guhXYycsOcARtIAS4b9W4qw0FXP5sipJafB453McQMjuJ/nX19Uu4vjqAbndZxl7DDpnuPBE0BIFlGSOl2RDgJ0mWuYSZyBiaGio4SqUqMLy4evsNX3An9mplAQYgxH3QQoamismbChw3bBqqZMCAwEAAaOCAYIwggF+MAkGA1UdEwQCMAAwEQYJYIZIAYb4QgEBBAQDAgZAMDMGCWCGSAGG+EIBDQQmFiRPcGVuU1NMIEdlbmVyYXRlZCBTZXJ2ZXIgQ2VydGlmaWNhdGUwHQYDVR0OBBYEFKmdvXHiKRfPK7Ril7HHtWjgC4y+MIG2BgNVHSMEga4wgauAFLv3Qlv+TKAu5aYX4JPeHDPHYsasoYGPpIGMMIGJMQswCQYDVQQGEwJOTDEVMBMGA1UECBMMWnVpZC1Ib2xsYW5kMRIwEAYDVQQHEwlQaWpuYWNrZXIxFDASBgNVBAoTC01PTy1BcmNoaXZlMSAwHgYJKoZIhvcNAQkBFhF0dmRpamVuQGdtYWlsLmNvbTEXMBUGA1UEAxMOTU9PLUFyY2hpdmUubmyCAQAwHQYDVR0lBBYwFAYIKwYBBQUHAwEGCCsGAQUFCAICMAsGA1UdDwQEAwIFoDAlBgNVHREEHjAcghpzaWduaW5nLmlkcC5tb28tYXJjaGl2ZS5ubDANBgkqhkiG9w0BAQsFAAOCAgEACcl027bjDDJJfB3u/amNPRGNgy/Yir+kMoRyDCDHYN9+bqwtY+5N1I/SwfeWcCJepe96CsZPrHypHzPOKNHEKyUwM8KrKF9rFI1ySRjEdeB/9FUbKCkXpTZTXT7OCqh1hxEjWGxfHQWj0uXeqS56zvDXY3uZECqexuO6xNNzS+ArRFePB/6tbm1tshdioRjHFGSNR6gG4YqSdZCJOzHSNqA2uwdnPR2kwbu2n60jL20hw9F9FDSj1GhccRuq3SurXZ+M/AJJ7fnVQdGREKgvfhisIWWvIagAns7DZ/r3VUvPmuGxee2ZSLgYVN8mfx3A/WEAAfKb/SgRUvpOa8z7sFV6sUx/9hbfustdDb3jTGRzplhpz403HXXQmf/P7MNM5zOg0TEWJsLsv7lmMbBY796x6rafJ5WFxvhyGCr2mDqRP6H2y1kmoVNEIAeSHhJGIj9Kki+fqChSQFNWmtNzz11C88TNnr6Iol5g/pHiFhGcvnpFSiCQ4gXNoHzHAfPZ9gwZyARuwRjKR3u0D2PtRUAe8YYddpL51GzHmNF9yQyaPagqLcdWbPlMb2Gjs5faWjpAhiVyCR8zlzvN9+5ZbQK8hpp4S/aV1XsXINJMHf7QA0KZfgnIg91lda4siaQbuNYWg4jCkUBe9ugqhOL8RKkJPGevlEvFMh74VHrQjjA=</ds:X509Certificate>
+        </ds:X509Data>
+      </ds:KeyInfo>
+    </md:KeyDescriptor>
+    <md:SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Location="https://idp.example.org/saml2/idp/SingleLogoutService.php"/>
+    <md:NameIDFormat>urn:oasis:names:tc:SAML:2.0:nameid-format:transient</md:NameIDFormat>
+    <md:SingleSignOnService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Location="https://idp.example.org/saml2/idp/SSOService.php"/>
+  </md:IDPSSODescriptor>
+</md:EntityDescriptor>
+XMLDOC;
+
+        $dom = new \DOMDocument('1.0');
+        $dom->loadXML($xml, LIBXML_NONET);
         $res = XML::isValid($dom, $schema);
-
         $this->assertTrue($res);
     }
 
-
     /**
      * @covers \SimpleSAML\Utils\XML::checkSAMLMessage()
      * @return void