@Test
@PrepareForTest(FileOpener.class)
public void testOpen() throws IOException {

  final byte[] content = randomUUID().toString().getBytes();
  mockStatic(Files.class);
  ByteArrayInputStream inMock = new ByteArrayInputStream(content);
  Mockito.when(Files.newInputStream(any(Path.class))).thenReturn(inMock);
  final Path path = mock(Path.class);
  final FileOpener fileOpener = new FileOpener(path);
  try (final InputStream in = fileOpener.get()) {
    assertArrayEquals(content, from(in));
  }
}