Fixed with the 1.0.4.GA release of jbossretro:

[starksm@succubus container]$ ant -buildfile build-test14.xml -Dtest=org.jboss.test.virtual.test.FileVFSContextUnitTestCase one-test
Buildfile: build-test14.xml
...
one-test:
    [mkdir] Created dir: /home/svn/JBossMC/jbossmc/container/output/reports
    [mkdir] Created dir: /home/svn/JBossMC/jbossmc/container/output/log
    [junit] Running org.jboss.test.virtual.test.FileVFSContextUnitTestCase
    [junit] Tests run: 14, Failures: 0, Errors: 0, Time elapsed: 0.32 sec

BUILD SUCCESSFUL
Total time: 1 second

Scott M Stark wrote:

The vfs error problems are the use the URL.toURI method.

<error message="java.net.URL.toURI()Ljava/net/URI;" type="java.lang.NoSuchMethodError">
java.lang.NoSuchMethodError: java.net.URL.toURI()Ljava/net/URI;
    at org.jboss.virtual.plugins.context.file.FileSystemContext.<init>(FileSystemContext.java:113)
    at org.jboss.test.virtual.test.FileVFSContextUnitTestCase.getVFSContext(FileVFSContextUnitTestCase.java:53)
    at org.jboss.test.virtual.test.AbstractVFSContextTest.testVisitNullVisitor(AbstractVFSContextTest.java:235)
</error>

http://jira.jboss.com/jira/browse/JBBUILD-325