Alerting: add collision safe update function for alertmanager configurations (#46692)

* Alerting: add collision safe update function for alertmanager configurations

* fix typo

* use bootstrap func for tests

* move hash calculation to store

* remove icons lol

* remove removed field

pkg/services/ngalert/notifier/testing.go

@@ -2,6 +2,9 @@ package notifier
 
 import (
 	"context"
+	"crypto/md5"
+	"errors"
+	"fmt"
 	"strings"
 	"sync"
 	"testing"
@@ -67,6 +70,20 @@ func (f *FakeConfigStore) SaveAlertmanagerConfigurationWithCallback(_ context.Co
 	return nil
 }
 
+func (f *FakeConfigStore) UpdateAlertManagerConfiguration(cmd *models.SaveAlertmanagerConfigurationCmd) error {
+	if config, exists := f.configs[cmd.OrgID]; exists && config.ConfigurationHash == cmd.FetchedConfigurationHash {
+		f.configs[cmd.OrgID] = &models.AlertConfiguration{
+			AlertmanagerConfiguration: cmd.AlertmanagerConfiguration,
+			OrgID:                     cmd.OrgID,
+			ConfigurationHash:         fmt.Sprintf("%x", md5.Sum([]byte(cmd.AlertmanagerConfiguration))),
+			ConfigurationVersion:      "v1",
+			Default:                   cmd.Default,
+		}
+		return nil
+	}
+	return errors.New("config not found or hash not valid")
+}
+
 type FakeOrgStore struct {
 	orgs []int64
 }