code: public boolean validateAgainst(String xmlContent, String xsdContent) {
          try {
              Source xsd = new SAXSource(new InputSource(new StringReader(xsdContent)));
              Source xml = new SAXSource(new InputSource(new StringReader(xmlContent)));
  
              SchemaFactory schemaFactory = SchemaFactory
                      .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
              Schema schema = schemaFactory.newSchema(xsd);
  
              Validator validator = schema.newValidator();
              validator.validate(xml);
              return true;
          } catch (SAXException e) {
              throw new SlimFixtureException(false, "XML Validation failed: " + e.getMessage());
          } catch (IOException e) {
              throw new SlimFixtureException(e);
          }
      }
docs: Validate currently loaded xml against an xsd
  @param xsdFileName the XSD schema file to use for validation
  @return true if the xml validates against the schema.
  Throws a descriptive SlimFixtureException when validation fails