order: extract query order sql generator

pkg/service/order.go

@@ -58,6 +58,23 @@ type QueryOrdersOptions struct {
 }
 
 func (s *OrderService) Query(options QueryOrdersOptions) ([]AggOrder, error) {
+	sql := genOrderSQL(options)
+
+	rows, err := s.DB.NamedQuery(sql, map[string]interface{}{
+		"exchange": options.Exchange,
+		"symbol":   options.Symbol,
+		"gid":      options.LastGID,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	defer rows.Close()
+
+	return s.scanAggRows(rows)
+}
+
+func genOrderSQL(options QueryOrdersOptions) string {
 	// ascending
 	ordering := "ASC"
 	switch v := strings.ToUpper(options.Ordering); v {
@@ -93,19 +110,7 @@ func (s *OrderService) Query(options QueryOrdersOptions) ([]AggOrder, error) {
 	sql += ` LIMIT ` + strconv.Itoa(500)
 
 	log.Info(sql)
-
+	return sql
-	rows, err := s.DB.NamedQuery(sql, map[string]interface{}{
-		"exchange": options.Exchange,
-		"symbol":   options.Symbol,
-		"gid":      options.LastGID,
-	})
-	if err != nil {
-		return nil, err
-	}
-
-	defer rows.Close()
-
-	return s.scanAggRows(rows)
 }
 
 func (s *OrderService) scanAggRows(rows *sqlx.Rows) (orders []AggOrder, err error) {

pkg/service/order_test.go

@@ -0,0 +1,24 @@
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_genOrderSQL(t *testing.T) {
+	t.Run("accept empty options", func(t *testing.T) {
+		o := QueryOrdersOptions{}
+		assert.Equal(t, "SELECT orders.*, IFNULL(SUM(t.price * t.quantity)/SUM(t.quantity), orders.price) AS average_price FROM orders LEFT JOIN trades AS t ON (t.order_id = orders.order_id) GROUP BY orders.gid  ORDER BY orders.gid ASC LIMIT 500", genOrderSQL(o))
+	})
+
+	t.Run("different ordering ", func(t *testing.T) {
+		o := QueryOrdersOptions{}
+		assert.Equal(t, "SELECT orders.*, IFNULL(SUM(t.price * t.quantity)/SUM(t.quantity), orders.price) AS average_price FROM orders LEFT JOIN trades AS t ON (t.order_id = orders.order_id) GROUP BY orders.gid  ORDER BY orders.gid ASC LIMIT 500", genOrderSQL(o))
+		o.Ordering = "ASC"
+		assert.Equal(t, "SELECT orders.*, IFNULL(SUM(t.price * t.quantity)/SUM(t.quantity), orders.price) AS average_price FROM orders LEFT JOIN trades AS t ON (t.order_id = orders.order_id) GROUP BY orders.gid  ORDER BY orders.gid ASC LIMIT 500", genOrderSQL(o))
+		o.Ordering = "DESC"
+		assert.Equal(t, "SELECT orders.*, IFNULL(SUM(t.price * t.quantity)/SUM(t.quantity), orders.price) AS average_price FROM orders LEFT JOIN trades AS t ON (t.order_id = orders.order_id) GROUP BY orders.gid  ORDER BY orders.gid DESC LIMIT 500", genOrderSQL(o))
+	})
+
+}