test for https://gist.github.com/2226436

RegexTest.java

import com.googlecode.totallylazy.Option;
import com.googlecode.totallylazy.Sequences;
import org.junit.Test;

import static com.googlecode.totallylazy.Sequences.sequence;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;

public class RegexTest {

    @Test
    public void findAllGroups() throws Exception {
        Regex regex = new Regex("(\\w)(\\w)(\\w)");
        Option<Iterable<String>> abc = regex.findGroupsIn("ABC");

        Iterable<String> expected = sequence("A", "B", "C");
        assertThat(abc.get(), equalTo(expected));
    }

    @Test
    public void findAllGroupsWithNoGroup() throws Exception {
        Regex regex = new Regex(".*");
        Option<Iterable<String>> abc = regex.findGroupsIn("ABC");

        Iterable<String> expected = Sequences.empty(String.class);
        assertThat(abc.get(), equalTo(expected));
    }
    
    @Test
    public void findAllGroupsWithNoMatch() throws Exception {
        Regex regex = new Regex("XYZ");
        Option<Iterable<String>> abc = regex.findGroupsIn("ABC");

        assertThat(abc.isEmpty(), is(true));
    }

    @Test
    public void findIn() throws Exception {
        Regex regex = new Regex("[A-Z]+");
        Option<String> foundValue = regex.findIn("asdfABCasdf");

        assertThat(foundValue.get(), equalTo("ABC"));
    }
    
    @Test
    public void doesNotFindIn() throws Exception {
        Regex regex = new Regex("[A-Z]+");
        Option<String> foundValue = regex.findIn("asdf");

        assertThat(foundValue.isEmpty(), is(true));
    }

    @Test
    public void findFirstGroupIn() throws Exception {
        Regex regex = new Regex("goo(.*)");
        Option<String> firstGroup = regex.findFirstGroupIn("gooFOO");
        
        assertThat(firstGroup.get(), equalTo("FOO"));
    }
    
    @Test
    public void findFirstGroupWithNoGroup() throws Exception {
        Regex regex = new Regex("blah");
        Option<String> firstGroup = regex.findFirstGroupIn("blahblah");
        
        assertThat(firstGroup.isEmpty(), is(true));
    }
    
    @Test
    public void matches() throws Exception {
        Regex regex = new Regex(".*FOO");
        
        assertThat(regex.matches("gooFOO"), is(true));
    }

    @Test
    public void doesNotMatch() throws Exception {
        Regex regex = new Regex("FOO");

        assertThat(regex.matches("BAR"), is(false));
    }
}