@Test
public void testSourceToString() throws Exception {

  Source source = (Source) CloudBigtableIO.read(scanConfig);
  byte[] startKey = "abc d".getBytes();
  byte[] stopKey = "def g".getBytes();
  BoundedSource<Result> sourceWithKeys = source.createSourceWithKeys(startKey, stopKey, 10);
  assertEquals("Split start: 'abc d', end: 'def g', size: 10.", sourceWithKeys.toString());
  startKey = new byte[] {0, 1, 2, 3, 4, 5};
  stopKey = new byte[] {104, 101, 108, 108, 111}; // hello
  sourceWithKeys = source.createSourceWithKeys(startKey, stopKey, 10);
  assertEquals(
      "Split start: '\\x00\\x01\\x02\\x03\\x04\\x05', end: 'hello', size: 10.",
      sourceWithKeys.toString());
}