### Question:
Tracker implements TrackerMBean { public void addTenant(String tenantId) { tenantIds.add(tenantId); log.info("[TRACKER] tenantId " + tenantId + " added."); } private  Tracker(); static Tracker getInstance(); synchronized void register(); void addTenant(String tenantId); void removeTenant(String tenantId); void removeAllTenants(); Set getTenants(); void addMetricName(String metricName); void removeMetricName(String metricName); void removeAllMetricNames(); Set<String> getMetricNames(); void setIsTrackingDelayedMetrics(); void resetIsTrackingDelayedMetrics(); boolean getIsTrackingDelayedMetrics(); boolean isTracking(String tenantId); boolean doesMessageContainMetricNames(String logmessage); void track(HttpRequest request); void trackResponse(HttpRequest request, FullHttpResponse response); void trackDelayedMetricsTenant(String tenantid, final List<Metric> delayedMetrics); void trackDelayedAggregatedMetricsTenant(String tenantId, long collectionTimeMs, long delayTimeMs, List<String> delayedMetricNames); static final String trackerName; }### Answer:
@Test public void testAddTenant() { tracker.addTenant(testTenant1); Set tenants = tracker.getTenants(); assertTrue( "tenant " + testTenant1 + " not added", tracker.isTracking( testTenant1 ) ); assertTrue( "tenants.size not 1", tenants.size() == 1 ); assertTrue( "tenants does not contain " + testTenant1, tenants.contains( testTenant1 ) ); }