### Question:
ExperimentManager { Experiment addExperiment (Experiment experiment) { allExperiments.add(experiment); return experiment; }  void setExperimentBackoffPeriod(Duration experimentBackoffPeriod); boolean areExperimentsInProgress();  }### Answer:
@Test public void addExperiment () { Experiment experiment = mock(Experiment.class); assertSame(experiment, experimentManager.addExperiment(experiment)); assertThat(experimentManager.getAllExperiments(), containsInAnyOrder(experiment)); }