### Question:
BackendBase implements TraceeBackend { @Override public String getSessionId() { return get(TraceeConstants.SESSION_ID_KEY); }  @Override final TraceeFilterConfiguration getConfiguration(); @Override final TraceeFilterConfiguration getConfiguration(String profileName); @Override String getInvocationId(); @Override String getSessionId();  }### Answer:
@Test public void sessionIdShortcutShouldReturnTheSessionIdIfSet() { when(unit.get(eq(TraceeConstants.SESSION_ID_KEY))).thenReturn("ourSessionId"); assertThat(unit.getSessionId(), is("ourSessionId")); }
@Test public void sessionIdShortcutShouldReturnNullIfNoSessionIdIsSet() { assertThat(unit.getSessionId(), is(nullValue())); }