두 줄 이상의 공백 라인을 제거하는 테스트 코드

@RunWith(AndroidJUnit4.class)
public class ExampleInstrumentedTest {

    private static final Pattern pattern = Pattern.compile("^\\s+\n|\\n\\s+\\n|\\n\\n|\\s+$");

    private void removeBlankLines(SpannableStringBuilder sb) {
        Matcher matcher = pattern.matcher(sb);
        ArrayList<Pair<Integer, Integer>> matchList = new ArrayList<>();
        while (matcher.find()) {
            matchList.add(new Pair<>(matcher.start(), matcher.end()));
        }

        for (int i = matchList.size() - 1; i >= 0; i--) {
            int start = matchList.get(i).first;
            int end = matchList.get(i).second;
            sb.delete(start, end);
            sb.insert(start, "\n");
        }

        if (sb.length() > 0) {
            if (sb.charAt(0) == '\n') {
                sb.delete(0, 1);
            }
        }
        if (sb.length() > 0) {
            if (sb.charAt(sb.length() - 1) == '\n') {
                sb.delete(sb.length() - 1, sb.length());
            }
        }
    }

    @Test
    public void test() throws Exception {
         String[][] tests = {
                {"  ", ""},
                {"  \n", ""},
                {"1", "1"},
                {"12", "12"},
                {"1\n", "1"},
                {"\n1", "1"},
                {"\n\n1", "1"},
                {"1\n\n", "1"},
                {"\n  \n1", "1"},
                {"1\n  \n", "1"},
                {"  1\n  \n", "  1"},
                {"1  \n", "1"},
                {"\n1\n", "1"},
                {"\n\n1\n", "1"},
                {"   \n   \n1\n", "1"},
                {"1\n2", "1\n2"},
                {"1\n2  ", "1\n2"},
                {"1\n2  \n", "1\n2"},
                {"1\n\n2", "1\n2"},
                {"1\n\n\n2", "1\n2"},
                {"1\n  \n\n2", "1\n2"},
                {"1\n  \n   \n2", "1\n2"},
                {"1\n  \n   \n2\n  3  \n", "1\n2\n  3"},
                {"1\n\n\n2\n\n\n\n3", "1\n2\n3"},
                {"1\n\n\n2\n\n\n\n3\n  \n4", "1\n2\n3\n4"},
                {"  \na", "a"},
                {" \n \n \n \na", "a"},
                {"  \n  \n  \n  \na", "a"},
                {"  a  ", "  a"},
                {"  a  \nz", "  a  \nz"},
                {"  a  \n\nk", "  a  \nk"},
                {"  a  \n\n\nd\n\n", "  a  \nd"},
                {"  a  \n\n\ne\n  \n", "  a  \ne"},
                {"  a  \n\n\nf  \n  \n", "  a  \nf"},
                {"  a  \n\n\ng  \n  \n  ", "  a  \ng"},
                {"  a  \n\n\nb  \n  \n  k", "  a  \nb  \n  k"},
        };

        for (String[] test : tests) {
            SpannableStringBuilder sb = new SpannableStringBuilder(test[0]);
            removeBlankLines(sb);
            assertEquals(test[1], sb.toString());
        }
    }
}