### Question:
FileValidator implements Validator<String> { @Override public boolean isValid(String input) { return isNotBlank(input) && Files.exists(Paths.get(input)); }  @Override boolean isValid(String input);  }### Answer:
@Test public void testNegative() { Assert.assertFalse(victim.isValid("/Chuck/Norris")); }
@Test public void testPositive() throws IOException { Path test = Files.createTempFile("tmp", "test"); Assert.assertTrue(victim.isValid(test.toAbsolutePath().toString())); Files.delete(test); }
@Test public void testAllowBlank() { Assert.assertFalse(victim.isValid("")); Assert.assertTrue(Validators.validEmpty(victim).isValid("")); }