@Test
  public void testNullPointerExceptions() throws IOException {
    FileChannel channel = channel(regularFile(100), READ, WRITE);

    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(channel);
  }
Most of the behavior of {@link JimfsFileChannel} is handled by the {@link RegularFile}
implementations, so the thorough tests of that are in {@link RegularFileTest}. This mostly tests
interactions with the file and channel positions.

@author Colin Decker
jimfs/src/test/java/com/google/common/jimfs/JimfsFileChannelTest.java