@Test
public void testWriteMatrix() throws Exception {

    Path matrixFile = Paths.get("target/testMatrix");
    Path matrixIndexFile = Paths.get("target/testMatrix_id2index");
    DataMatrixIO.writeMatrix(dataMatrix, matrixFile.toString(), true);
    assertFileExistsThenDelete(matrixFile);
    assertFileExistsThenDelete(matrixIndexFile);
}