### Question:
EnvironmentVariableConfigurationSource extends AbstractConfigurationSource { public EnvironmentVariableConfigurationSource(final int priority) { super(priority, "EnvironmentVariable"); } EnvironmentVariableConfigurationSource(final int priority); @Override Configuration configuration();  }### Answer:
@Test public void testEnvironmentVariableConfigurationSource() { EnvironmentVariableConfigurationSource cs = new EnvironmentVariableConfigurationSource(0); assertEquals(cs.priority(), 0); }