sudo port selfupdate
sudo port install git-core

You can find other GitHub installation instructions at http://help.github.com/mac-git-installation/

Once you have GitHub installed, open Terminal and run these commands to install the TextMate bundles:

mkdir -p /Library/Application\ Support/TextMate/Bundles
cd /Library/Application\ Support/TextMate/Bundles/
git clone git://github.com/alkemist/groovy.tmbundle.git
git clone git://github.com/alkemist/Groovy-Grails.tmbundle.git

I hope this helps!

The Groovy website’s instructions for installing the TextMate bundle are very vague.  They point you to the bundle location and link you to the TextMate bundle instructions (which are useful, but long when all you want to know is how to install bundles).  Here’s all you need to do to install the Groovy and Grails bundles.

Open Terminal and run these commands:

mkdir -p /Library/Application\ Support/TextMate/Bundles
cd /Library/Application\ Support/TextMate/Bundles/
svn co http://svn.textmate.org/trunk/Bundles/Groovy.tmbundle
svn co http://svn.textmate.org/trunk/Bundles/Groovy%20Grails.tmbundle

I dug through the generated build-impl.xml file to find out why, and found that JUnit is being passed a list of .java files.  The Groovy tests are .groovy, so they won’t run.  JUnit will accept .class files, and since Java and Groovy are compiled to .class files by NetBeans tests in both languages will run this way.  I edited build.xml and overrode three targets from build-impl.xml.  With these changes you can run individual Java and Groovy tests or run them as part of a full test run.  I highlighted the changes I made from the original build-impl.xml targets in red.  If you copy/paste the xmlns attribute and these targets into build.xml you should be able to run all of your Groovy and Java tests in NetBeans.

Note: Be sure to edit build.xml, not build-impl.xml since it can regenerate and overwrite your changes.  Yes, I found this out the hard way

build.xml:

<?xml version="1.0" encoding="UTF-8"?>

<project name="TestGroovy" default="default" basedir="." xmlns:j2seproject3="http://www.netbeans.org/ns/j2se-project/3">
    <description>Builds, tests, and runs the project TestGroovy.</description>
    <import file="nbproject/build-impl.xml"/>

    <target depends="init,compile-test,-pre-test-run" if="have.tests" name="-do-test-run">
        <j2seproject3:junit testincludes="**/*Test.class"/>
    </target>

    <target depends="init,compile-test-single,-pre-test-run-single" if="have.tests" name="-do-test-run-single">
        <fail unless="test.includes">Must select some files in the IDE or set test.includes</fail>
        <taskdef name="groovy" classname="org.codehaus.groovy.ant.Groovy" classpath="${javac.classpath}"/>
        <groovy>
            properties."test.includes.class" = properties."test.includes".split("\\.")[0] + ".class"
        </groovy>
        <j2seproject3:junit excludes="" includes="${test.includes.class}"/>
    </target>

    <target name="-init-macrodef-junit">
        <macrodef name="junit" uri="http://www.netbeans.org/ns/j2se-project/3">
            <attribute default="${includes}" name="includes"/>
            <attribute default="${excludes}" name="excludes"/>
            <attribute default="**" name="testincludes"/>
            <sequential>
                <junit dir="${work.dir}" errorproperty="tests.failed" failureproperty="tests.failed" fork="true" showoutput="true">
                    <batchtest todir="${build.test.results.dir}">
                        <fileset dir="${build.test.classes.dir}" excludes="@{excludes},${excludes}" includes="@{includes}">
                            <filename name="@{testincludes}"/>
                        </fileset>
                    </batchtest>
                    <classpath>
                        <path path="${run.test.classpath}"/>
                    </classpath>
                    <syspropertyset>
                        <propertyref prefix="test-sys-prop."/>
                        <mapper from="test-sys-prop.*" to="*" type="glob"/>
                    </syspropertyset>
                    <formatter type="brief" usefile="false"/>
                    <formatter type="xml"/>
                    <jvmarg line="${run.jvmargs}"/>
                </junit>
            </sequential>
        </macrodef>
    </target>
</project>