@Test
public void testCalculatesCorrectMeans() {

    double[] expectedMeans = new double[] {0.5, 1.75, 4.5, 0.875};
    final Vectorizer<Integer, Vector, Integer, Double> vectorizer = new DummyVectorizer<>(0, 1, 2, 3);
    StandardScalerPreprocessor<Integer, Vector> preprocessor = (StandardScalerPreprocessor<Integer, Vector>)standardizationTrainer.fit(
        TestUtils.testEnvBuilder(),
        datasetBuilder,
        vectorizer
    );
    assertArrayEquals(expectedMeans, preprocessor.getMeans(), 1e-8);
}