Technoetic

A recent article on InfoQ (Boost your Java Test with Ruby and JtestR) described a new framework for doing Java testing using JRuby. The article includes the following test case to highlight it’s features.

import java.util.HashMap

describe "An empty", HashMap do
 before :each do
  @hash_map = HashMap.new
 end
 it "should be able to add an entry to it" do
  @hash_map.put "foo", "bar"
  @hash_map.get("foo").should == "bar"
 end
 it "should return a keyset iterator that throws an exception on next" do
  proc do
   @hash_map.key_set.iterator.next
  end.should raise_error(java.util.NoSuchElementException)
 end
end

What is the point of this example? Is there really a significant difference between this example and the following JUnit4 test class?

import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;

import java.util.HashMap;
import java.util.NoSuchElementException;

import org.junit.Test;

public class HashMapTest {
    private HashMap<String,String> hashMap =
            new HashMap<String,String>();

    @Test
    public void shouldBeAbleToAddAnEntryToIt() {
        hashMap.put("foo", "bar");
        assertThat(hashMap.get("foo"), is("bar"));
    }

    @Test(expected = NoSuchElementException.class)
    public void shouldReturnAKeysetIteratorThatThrowsAnExceptionOnNext() {
        hashMap.keySet().iterator().next();
    }

}

Sure, the syntax is a bit different and the Java version is slightly more verbose with it’s access specifiers and type declarations. However, the Java version runs fast enough that you don’t need to set up a Ant server to get reasonable performance from your tests (as recommended in the article for JTestR).

I’m not questioning that scripting can be useful in unit tests. However, I’d think that Groovy’s superior Java integration would make it a better choice for this purpose than JRuby. Does anybody know of some compelling, pragmatic examples of the relative benefit of JRuby over Groovy for Java test scripting purposes?