File dir = getContext().getDir("testInitialWrite", Context.MODE_PRIVATE);
File file = File.createTempFile("testInitialWrite", "dat", dir);
file.deleteOnExit();
assertEquals(0, FileUtils.readTextFile(file, 0, null).length());
// The constructor has the side effect of writing to file
new EntropyMixer(getContext(), "/dev/null", file.getCanonicalPath(), "/dev/null");
assertTrue(FileUtils.readTextFile(file, 0, null).length() > 0);