Keep one connection open for the lifetime of sqlcmd (#71)

* add test for persistent connection

* keep single connection open

Author: shueybubbles

pkg/sqlcmd/format_test.go

@@ -4,6 +4,7 @@
 package sqlcmd
 
 import (
+	"context"
 	"strings"
 	"testing"
 
@@ -62,7 +63,7 @@ func TestCalcColumnDetails(t *testing.T) {
 	if assert.NoError(t, err, "ConnectDB failed") {
 		defer db.Close()
 		for x, test := range tests {
-			rows, err := db.Query(test.query)
+			rows, err := db.QueryContext(context.Background(), test.query)
 			if assert.NoError(t, err, "Query failed: %s", test.query) {
 				defer rows.Close()
 				cols, err := rows.ColumnTypes()

pkg/sqlcmd/sqlcmd.go

@@ -50,7 +50,7 @@ type Console interface {
 type Sqlcmd struct {
 	lineIo           Console
 	workingDirectory string
-	db               *sql.DB
+	db               *sql.Conn
 	out              io.WriteCloser
 	err              io.WriteCloser
 	batch            *Batch
@@ -232,8 +232,7 @@ func (s *Sqlcmd) ConnectDb(connect *ConnectSettings, nopw bool) error {
 	if err != nil {
 		return err
 	}
-	db := sql.OpenDB(connector)
-	err = db.Ping()
+	db, err := sql.OpenDB(connector).Conn(context.Background())
 	if err != nil {
 		fmt.Fprintln(s.GetOutput(), err)
 		return err

pkg/sqlcmd/sqlcmd_test.go

@@ -87,7 +87,7 @@ func TestSqlCmdConnectDb(t *testing.T) {
 	}
 }
 
-func ConnectDb(t testing.TB) (*sql.DB, error) {
+func ConnectDb(t testing.TB) (*sql.Conn, error) {
 	v := InitializeVariables(true)
 	s := &Sqlcmd{vars: v}
 	s.Connect = newConnect(t)
@@ -408,6 +408,15 @@ func TestSqlCmdDefersToPrintError(t *testing.T) {
 	}
 }
 
+func TestSqlCmdMaintainsConnectionBetweenBatches(t *testing.T) {
+	s, buf := setupSqlCmdWithMemoryOutput(t)
+	defer buf.Close()
+	err := runSqlCmd(t, s, []string{"CREATE TABLE #tmp1 (col1 int)", "insert into #tmp1 values (1)", "GO", "select * from #tmp1", "drop table #tmp1", "GO"})
+	if assert.NoError(t, err, "runSqlCmd failed") {
+		assert.Equal(t, oneRowAffected+SqlcmdEol+"1"+SqlcmdEol+SqlcmdEol+oneRowAffected+SqlcmdEol, buf.buf.String(), "Sqlcmd uses the same connection for all queries")
+	}
+}
+
 // runSqlCmd uses lines as input for sqlcmd instead of relying on file or console input
 func runSqlCmd(t testing.TB, s *Sqlcmd, lines []string) error {
 	t.Helper()