Privatise DB repository field and add transformer test

pkg/transformers/tend/repository.go

@@ -21,11 +21,11 @@ import (
 )
 
 type TendRepository struct {
-	DB *postgres.DB
+	db *postgres.DB
 }
 
 func (repository TendRepository) Create(headerId int64, models []interface{}) error {
-	tx, err := repository.DB.Begin()
+	tx, err := repository.db.Begin()
 	if err != nil {
 		return err
 	}
@@ -61,7 +61,7 @@ func (repository TendRepository) Create(headerId int64, models []interface{}) er
 }
 
 func (repository TendRepository) MarkHeaderChecked(headerId int64) error {
-	_, err := repository.DB.Exec(`INSERT INTO public.checked_headers (header_id, tend_checked)
+	_, err := repository.db.Exec(`INSERT INTO public.checked_headers (header_id, tend_checked)
 		VALUES ($1, $2)
 	ON CONFLICT (header_id) DO
 		UPDATE SET tend_checked = $2`, headerId, true)
@@ -70,7 +70,7 @@ func (repository TendRepository) MarkHeaderChecked(headerId int64) error {
 
 func (repository TendRepository) MissingHeaders(startingBlockNumber, endingBlockNumber int64) ([]core.Header, error) {
 	var result []core.Header
-	err := repository.DB.Select(
+	err := repository.db.Select(
 		&result,
 		`SELECT headers.id, headers.block_number FROM headers
 				LEFT JOIN checked_headers on headers.id = header_id
@@ -80,12 +80,12 @@ func (repository TendRepository) MissingHeaders(startingBlockNumber, endingBlock
                	AND headers.eth_node_fingerprint = $3`,
 		startingBlockNumber,
 		endingBlockNumber,
-		repository.DB.Node.ID,
+		repository.db.Node.ID,
 	)
 
 	return result, err
 }
 
 func (repository *TendRepository) SetDB(db *postgres.DB) {
-	repository.DB = db
+	repository.db = db
 }