### Question:
EphemeralKeyManager { @Nullable @VisibleForTesting EphemeralKey getEphemeralKey() { return mEphemeralKey; } EphemeralKeyManager(
            @NonNull EphemeralKeyProvider ephemeralKeyProvider,
            @NonNull KeyManagerListener keyManagerListener,
            long timeBufferInSeconds,
            @Nullable Calendar overrideCalendar);   }### Answer:
@Test @SuppressWarnings("unchecked") public void createKeyManager_updatesEphemeralKey_notifiesListener() { EphemeralKey testKey = EphemeralKey.fromString(FIRST_SAMPLE_KEY_RAW); assertNotNull(testKey); mTestEphemeralKeyProvider.setNextRawEphemeralKey(FIRST_SAMPLE_KEY_RAW); EphemeralKeyManager keyManager = new EphemeralKeyManager( mTestEphemeralKeyProvider, mKeyManagerListener, TEST_SECONDS_BUFFER, null); verify(mKeyManagerListener, times(1)).onKeyUpdate( any(EphemeralKey.class), (String) isNull(), (Map<String, Object>) isNull()); assertNotNull(keyManager.getEphemeralKey()); assertEquals(testKey.getId(), keyManager.getEphemeralKey().getId()); }