As the Arquillian JMX protocol doesn't currently work for EARs in AS7 (AS7-1696), I tried using the Servlet 3.0 protocol. However the test runner fails to contact the servlet:

java.lang.IllegalStateException: Error launching request at http://127.0.0.1:8080/test/ArquillianServletRunner?outputMode=serializedObject&className=com.example.ExampleITCase&methodName=testMethod. No result returned
at org.jboss.arquillian.protocol.servlet.ServletMethodExecutor.executeWithRetry(ServletMethodExecutor.java:158)
at org.jboss.arquillian.protocol.servlet.ServletMethodExecutor.invoke(ServletMethodExecutor.java:118)
... 75 more

The servlet is actually deployed at:

http://127.0.0.1:8080/test.war/ArquillianServletRunner

Because Arquillian has added the following to my EAR's application.xml:
<module>
<web>
<web-uri>test.war</web-uri>
<context-root>test.war</context-root>
</web>
</module>

This can be traced to org.jboss.arquillian.protocol.servlet.v_3.ServletProtocolDeploymentPackager:

applicationXml.webModule(wrappedWar.getName(), wrappedWar.getName());