Method method = getClass().getDeclaredMethod(testMethodName, new Class[]{java.lang.String.class});
MetaMethod testMethod = new MetaMethod(method, metaClass);
metaClass.addMetaMethod(testMethod);
String testRetType = "java.lang.String";
String[] testParamTypes = new String[]{"java.lang.String"};
IMetaMember result = metaClass.getMemberFromSignature(MemberSignatureParts.fromParts(metaClass.getFullyQualifiedName(),testMethodName, testRetType, testParamTypes));