@Test
public void should_concatenate_files() throws IOException {

    Files.write("file1".getBytes(), temporaryFolder.newFile("file1.js"));
    Files.write("file2".getBytes(), temporaryFolder.newFile("file2.js"));
    List<Path> files = Arrays.asList(temporaryFolder.toPath().resolve("file1.js"), temporaryFolder.toPath()
            .resolve("file2.js"));
    byte[] content = FilesConcatenator.concat(files);
    assertThat(content).isEqualTo("file1file2".getBytes());
}