private Instances loadInstancesFromARFF(String filename, String className) throws IOException {
File file = new File(TEST_RESOURCES, filename);
assertTrue(file.exists());
ArffLoader loader = new ArffLoader();
loader.setFile(file);
Instances insts = loader.getDataSet();
Attribute classAttribute = insts.attribute(className);
insts.setClass(classAttribute);
return insts;
}