Storage: Watch tests (#85496)

* basic watch tests working

* refactor to read previous event within poller

* add watch test files

* cleanup

* watch tests passing

* debug cleanup

* special handling for canceled context

* cleanup

* fix wire

* fix sqlite_sequence cleanup issue

* move watch tests to integration, wait for provisioned dashboards

* handle context deadline exceeded and eof errors

* add comment about sleep

pkg/services/sqlstore/migrator/migrator.go

@@ -210,7 +210,9 @@ func (mg *Migrator) run() (err error) {
 		err := mg.InTransaction(func(sess *xorm.Session) error {
 			err := mg.exec(m, sess)
 			// if we get an sqlite busy/locked error, sleep 100ms and try again
-			if errors.Is(err, sqlite3.ErrLocked) || errors.Is(err, sqlite3.ErrBusy) {
+			cnt := 0
+			for cnt < 3 && (errors.Is(err, sqlite3.ErrLocked) || errors.Is(err, sqlite3.ErrBusy)) {
+				cnt++
 				mg.Logger.Debug("Database locked, sleeping then retrying", "error", err, "sql", sql)
 				time.Sleep(100 * time.Millisecond)
 				err = mg.exec(m, sess)

pkg/services/sqlstore/migrator/sqlite_dialect.go

@@ -122,7 +122,11 @@ func (db *SQLite3) TruncateDBTables(engine *xorm.Engine) error {
 		}
 	}
 	if _, err := sess.Exec("UPDATE sqlite_sequence SET seq = 0 WHERE name != 'dashboard_acl';"); err != nil {
-		return fmt.Errorf("failed to cleanup sqlite_sequence: %w", err)
+		// if we have not created any autoincrement columns in the database this will fail, the error is expected and we can ignore it
+		// we can't discriminate based on code because sqlite returns a generic error code
+		if err.Error() != "no such table: sqlite_sequence" {
+			return fmt.Errorf("failed to cleanup sqlite_sequence: %w", err)
+		}
 	}
 	return nil
 }

pkg/services/sqlstore/sqlstore.go

@@ -151,7 +151,7 @@ func newSQLStore(cfg *setting.Cfg, engine *xorm.Engine,
 // Has to be done in a second phase (after initialization), since other services can register migrations during
 // the initialization phase.
 func (ss *SQLStore) Migrate(isDatabaseLockingEnabled bool) error {
-	if ss.dbCfg.SkipMigrations {
+	if ss.dbCfg.SkipMigrations || ss.migrations == nil {
 		return nil
 	}