Add integration test for AXIS2-6053 diagnostic hint through invoke() flow

Exercises the full SchemaValidationHandler.invoke() path with a SOAP
message containing an undeclared xmime:contentType attribute, triggering
a cvc-complex-type.3.2.2 validation error, and verifies the resulting
AxisFault includes the diagnostic hint about unresolved ref= attributes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: robertlazarski

modules/schema-validation/src/test/java/org/apache/axis2/validation/SchemaValidationHandlerTest.java

@@ -19,7 +19,26 @@
 package org.apache.axis2.validation;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
+import java.io.ByteArrayInputStream;
+import java.nio.charset.StandardCharsets;
+
+import javax.xml.transform.stream.StreamSource;
+
+import org.apache.axiom.om.OMAbstractFactory;
+import org.apache.axiom.om.OMElement;
+import org.apache.axiom.om.OMNamespace;
+import org.apache.axiom.soap.SOAPBody;
+import org.apache.axiom.soap.SOAPEnvelope;
+import org.apache.axiom.soap.SOAPFactory;
+import org.apache.axis2.AxisFault;
+import org.apache.axis2.context.ConfigurationContext;
+import org.apache.axis2.context.MessageContext;
+import org.apache.axis2.description.AxisService;
+import org.apache.axis2.engine.AxisConfiguration;
+import org.apache.ws.commons.schema.XmlSchema;
+import org.apache.ws.commons.schema.XmlSchemaCollection;
 import org.junit.jupiter.api.Test;
 import org.xml.sax.SAXException;
 
@@ -48,4 +67,68 @@ public void testAppendRefHintHandlesNullMessage() {
         String hint = SchemaValidationHandler.appendRefHint(ex);
         assertThat(hint).isEmpty();
     }
+
+    /**
+     * Integration test: invoke the handler with a SOAP message containing an
+     * attribute not declared in the schema, triggering cvc-complex-type.3.2.2,
+     * and verify the AxisFault message includes the diagnostic ref= hint.
+     */
+    @Test
+    public void testInvokeProducesRefHintForUnexpectedAttribute() throws Exception {
+        // Schema that defines <note> with child elements only — no attributes allowed
+        String xsd =
+                "<xs:schema xmlns:xs='http://www.w3.org/2001/XMLSchema'"
+                + " targetNamespace='http://example.com/test'"
+                + " xmlns:tns='http://example.com/test'"
+                + " elementFormDefault='qualified'>"
+                + "  <xs:element name='note'>"
+                + "    <xs:complexType>"
+                + "      <xs:sequence>"
+                + "        <xs:element name='to' type='xs:string'/>"
+                + "      </xs:sequence>"
+                + "    </xs:complexType>"
+                + "  </xs:element>"
+                + "</xs:schema>";
+
+        XmlSchemaCollection schemaCol = new XmlSchemaCollection();
+        XmlSchema schema = schemaCol.read(new StreamSource(
+                new ByteArrayInputStream(xsd.getBytes(StandardCharsets.UTF_8))));
+
+        // AxisService with the schema
+        AxisService service = new AxisService("TestService");
+        service.addSchema(schema);
+
+        // MessageContext
+        ConfigurationContext configCtx = new ConfigurationContext(new AxisConfiguration());
+        MessageContext msgCtx = configCtx.createMessageContext();
+        msgCtx.setAxisService(service);
+
+        // SOAP envelope whose body element has an attribute the schema doesn't allow
+        SOAPFactory sf = OMAbstractFactory.getSOAP11Factory();
+        SOAPEnvelope envelope = sf.createSOAPEnvelope();
+        SOAPBody body = sf.createSOAPBody(envelope);
+
+        OMNamespace tns = sf.createOMNamespace("http://example.com/test", "tns");
+        OMElement note = sf.createOMElement("note", tns);
+
+        // Add the required child so the only error is the unexpected attribute
+        OMElement to = sf.createOMElement("to", tns);
+        to.setText("Alice");
+        note.addChild(to);
+
+        // Add an attribute that the schema does not declare — triggers cvc-complex-type.3.2.2
+        OMNamespace xmimeNs = sf.createOMNamespace("http://www.w3.org/2005/05/xmlmime", "xmime");
+        note.addAttribute("contentType", "text/xml", xmimeNs);
+
+        body.addChild(note);
+        msgCtx.setEnvelope(envelope);
+
+        // Invoke the handler and assert the AxisFault contains the hint
+        SchemaValidationHandler handler = new SchemaValidationHandler();
+        assertThatThrownBy(() -> handler.invoke(msgCtx))
+                .isInstanceOf(AxisFault.class)
+                .hasMessageContaining("cvc-complex-type.3.2.2")
+                .hasMessageContaining("xs:attribute ref=")
+                .hasMessageContaining("not imported or could not be resolved");
+    }
 }