backport of commit 50a1f9e (#17466)

Co-authored-by: Chris Capurso <1036769+ccapurso@users.noreply.github.com>

vault/activity_log_util_common.go

@@ -74,7 +74,7 @@ func (a *ActivityLog) computeCurrentMonthForBillingPeriodInternal(ctx context.Co
 		if len(monthlyComputation) > 1 {
 			a.logger.Warn("monthly in-memory activitylog computation returned multiple months of data", "months returned", len(byMonth))
 		}
-		if len(monthlyComputation) >= 0 {
+		if len(monthlyComputation) > 0 {
 			return monthlyComputation[0], nil
 		}
 	}

vault/activity_log_util_common_test.go

@@ -125,4 +125,28 @@ func Test_ActivityLog_ComputeCurrentMonthForBillingPeriodInternal(t *testing.T)
 	if monthRecord.NewClients.Counts.NonEntityClients != 4 {
 		t.Fatalf("wrong number of new non entity clients. Expected 4, got %d", monthRecord.NewClients.Counts.NonEntityClients)
 	}
+
+	// Attempt to compute current month when no records exist
+	endTime = time.Now().UTC()
+	startTime = timeutil.StartOfMonth(endTime)
+	emptyClientsMap := make(map[int64]*processMonth, 0)
+	monthRecord, err = a.computeCurrentMonthForBillingPeriodInternal(context.Background(), emptyClientsMap, mockHLLGetFunc, startTime, endTime)
+	if err != nil {
+		t.Fatalf("failed to compute empty current month, err: %v", err)
+	}
+
+	// We should have 0 entity clients, nonentity clients,new entity clients
+	// and new nonentity clients
+	if monthRecord.Counts.EntityClients != 0 {
+		t.Fatalf("wrong number of entity clients. Expected 0, got %d", monthRecord.Counts.EntityClients)
+	}
+	if monthRecord.Counts.NonEntityClients != 0 {
+		t.Fatalf("wrong number of non entity clients. Expected 0, got %d", monthRecord.Counts.NonEntityClients)
+	}
+	if monthRecord.NewClients.Counts.EntityClients != 0 {
+		t.Fatalf("wrong number of new entity clients. Expected 0, got %d", monthRecord.NewClients.Counts.EntityClients)
+	}
+	if monthRecord.NewClients.Counts.NonEntityClients != 0 {
+		t.Fatalf("wrong number of new non entity clients. Expected 0, got %d", monthRecord.NewClients.Counts.NonEntityClients)
+	}
 }