### Question:
EnvironmentVariableConfigurationSource extends AbstractConfigurationSource { @Override public Configuration configuration() { return _configuration; } EnvironmentVariableConfigurationSource(final int priority); @Override Configuration configuration();  }### Answer:
@Test public void testConfiguration() { EnvironmentVariableConfigurationSource cs = new EnvironmentVariableConfigurationSource(0); assertNotNull(cs.configuration()); assertTrue(!Strings.isNullOrEmpty(cs.configuration().getPropertyValue("sun.management.compiler"))); }