@Test
public void appendCustomSeparatorLine() throws Exception {

    Connection conn = showDialog(TITLE, TEXT[0] + "\n").get();
    
    final int N = 10;
    final char c = '#';
    conn.appendSeparatorLine(N, c);
    
    char[] chars = new char[N];
    Arrays.fill(chars, c);
    String expected = String.format("%s%n%s%n", TEXT[0], String.valueOf(chars));
    
    String displayedText = windowFixture.textBox().text();
    assertEquals(expected, displayedText);
}