### Question:
FileArchivedExecutionGraphStore implements ArchivedExecutionGraphStore { @Override @Nullable public ArchivedExecutionGraph get(JobID jobId) { try { return archivedExecutionGraphCache.get(jobId); } catch (ExecutionException e) { LOG.debug("Could not load archived execution graph for job id {}.", jobId, e); return null; } } FileArchivedExecutionGraphStore(
			File rootDir,
			Time expirationTime,
			long maximumCacheSizeBytes,
			ScheduledExecutor scheduledExecutor,
			Ticker ticker); @Override int size(); @Override @Nullable ArchivedExecutionGraph get(JobID jobId); @Override void put(ArchivedExecutionGraph archivedExecutionGraph); @Override JobsOverview getStoredJobsOverview(); @Override Collection<JobDetails> getAvailableJobDetails(); @Nullable @Override JobDetails getAvailableJobDetails(JobID jobId); @Override void close();  }### Answer:
@Test public void testUnknownGet() throws IOException { final File rootDir = temporaryFolder.newFolder(); try (final FileArchivedExecutionGraphStore executionGraphStore = createDefaultExecutionGraphStore(rootDir)) { assertThat(executionGraphStore.get(new JobID()), Matchers.nullValue()); } }