Ruby:
    require 'test/unit'

    import 'com.alisoft.research.JRuby.service.KeywordFilterServiceImpl'

    class KeywordFilterServiceTest < Test::Unit::TestCase
        def setup
            @keywords = %w{X XX XXX XXXX XXXXX XXXXXX XXXXXXX}
        end
      
        def test_filter
            comments = random_comments
            service = KeywordFilterServiceImpl.new(@keywords.to_java :String)
            filted = service.filter(comments.to_java :String)

            forbiddens = service.getFiltedComments
          
            assert forbiddens.length == comments.length - filted.length
            assert_equal forbiddens.sort, (comments - filted).sort
        end
      
        def random_alphabetic(size=5)
            chars = ('a'..'z').to_a + ('A'..'Z').to_a
            (0...size).collect { chars[rand(chars.length)] }.join
        end
      
        def random_comments
            comments ||= []
            10.times do
                keyword = rand(10) % 3 == 0 ? ' ' : @keywords[rand(@keywords.length)]
                comment = random_alphabetic + keyword + random_alphabetic
                comments << comment
            end
            return comments
        end
    end

    Java:
    package com.alisoft.research.JRuby.test;

    import static org.junit.Assert.assertArrayEquals;
    import static org.junit.Assert.assertEquals;

    import Java.util.ArrayList;
    import Java.util.Arrays;
    import Java.util.List;

    import org.apache.commons.lang.RandomStringUtils;
    import org.apache.commons.lang.math.RandomUtils;
    import org.junit.Test;

    import com.alisoft.research.JRuby.service.KeywordFilterServiceImpl;

    public class KeywordFilterServiceTest {

        @Test
        public void testFilteredResults() {
            String[] comments = getRandomComments();

            KeywordFilterServiceImpl service = new KeywordFilterServiceImpl(
                    getKeywords());

            String[] filted = service.filter(comments);
            String[] forbiddens = service.getFiltedComments();

            assertEquals(filted.length + forbiddens.length, comments.length);

            assertArrayEquals(forbiddens, sub(comments, filted));
        }
        //实现减法操作
        private String[] sub(String[] all, String[] part) {
            List allList = new ArrayList(Arrays.asList(all));
            allList.removeAll(Arrays.asList(part));
            return allList.toArray(new String[allList.size()]);
        }

        private String[] getRandomComments() {
            String[] comments = new String[RandomUtils.nextInt(10)];
            for (int i = 0; i < comments.length; i++) {
                String comment = RandomStringUtils.randomAlphabetic(5);
                String keyword = RandomUtils.nextBoolean() ? getKeywords()[RandomUtils
                        .nextInt(getKeywords().length)]
                        : "";
                comment += keyword + RandomStringUtils.randomAlphabetic(5);
                comments[i] = comment;
            }
            return comments;
        }

        private String[] getKeywords() {
            String[] keywords = new String[] { "X", "XX", "XXX", "XXXX",
                    "XXXXX", "XXXXXX", "XXXXXXX" };
            return keywords;
        }

    }