Add test that highlights an issue regarding services

The waitgroup counter goes up before we even try to start
the service. So, if the start fails, the counter doesn't
go back down. This messes up the graceful shutdown of
cgr-engine.

servmanager/servmanager_test.go

@@ -0,0 +1,104 @@
+/*
+Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
+Copyright (C) ITsysCOM GmbH
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+*/
+
+package servmanager
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/cgrates/cgrates/config"
+	"github.com/cgrates/cgrates/utils"
+)
+
+type mockService struct {
+	name      string
+	start     func(*mockService) error
+	reload    func(*mockService) error
+	shutdown  func(*mockService) error
+	isRunning bool
+	shouldRun bool
+}
+
+func (m *mockService) Start() error {
+	return m.start(m)
+}
+func (m *mockService) Reload() error {
+	return m.reload(m)
+}
+func (m *mockService) Shutdown() error {
+	return m.shutdown(m)
+}
+func (m *mockService) IsRunning() bool {
+	return m.isRunning
+}
+func (m *mockService) ShouldRun() bool {
+	return m.shouldRun
+}
+func (m *mockService) ServiceName() string {
+	return m.name
+}
+
+// This test aims to highlight an issue related to services, where the waitgroup counter goes
+// up before we even try to start the service. So, if the start fails, the counter doesn't go
+// back down. This messes up the graceful shutdown of the cgr-engine.
+func TestStartServicesDeadlock(t *testing.T) {
+	t.Skip("Skipping this test until we start working on the service implementation")
+	cfg := config.NewDefaultCGRConfig()
+	shdWg := new(sync.WaitGroup)
+	shdChan := utils.NewSyncedChan()
+	srvManager := NewServiceManager(cfg, shdChan, shdWg, nil)
+
+	// The service will fail to start due to the utils.ErrNotImplemented error.
+	mockSrv := &mockService{
+		name: "mockService",
+		start: func(m *mockService) error {
+			return utils.ErrNotImplemented
+		},
+		reload: func(m *mockService) error {
+			return nil
+		},
+		shutdown: func(m *mockService) error {
+			m.isRunning = false
+			return nil
+		},
+		isRunning: false,
+		shouldRun: true,
+	}
+
+	srvManager.AddServices(mockSrv)
+	err := srvManager.StartServices()
+	if err != nil {
+		t.Fatal(err)
+	}
+	<-shdChan.Done()
+	done := make(chan struct{})
+	go func() {
+		shdWg.Wait()
+		close(done)
+	}()
+	select {
+	case <-done:
+		if mockSrv.isRunning {
+			t.Error("expected mock service to be stopped")
+		}
+	case <-time.After(2 * time.Millisecond):
+		t.Error("waitgroup shdWg's counter is not 0")
+	}
+}