public String getStringForDisplay() {
        if (isEmpty()) {
            return "";
        }
        StringBuilder display = new StringBuilder();
        for (IgnoredFiles ignoredFiles : this) {
            display.append(ignoredFiles.getPattern()).append(",");
        }
        return display.substring(0, display.length() - 1);
    }
@Test
    public void shouldReturnEmptyTextToDisplayWhenFilterIsEmpty() {
        assertThat(new Filter().getStringForDisplay(), is(""));
    }