@Override
    public void run() {
        // top-level command, do nothing
    }
@Test
    public void test_listSnapshots() {
        // Given
        // When
        run("list-snapshots");

        // Then
        String actual = captureOut();
        assertTrue("output should contain one line (the table header), but contains:\n" + actual,
                actual.trim().indexOf('\n') < 0 && !actual.isEmpty());
    }