Merge pull request #926 from lib/ping-empty

allow ping during a failed txn

Author: maddyblue

conn_go18.go

@@ -79,7 +79,7 @@ func (cn *conn) Ping(ctx context.Context) error {
 	if finish := cn.watchCancel(ctx); finish != nil {
 		defer finish()
 	}
-	rows, err := cn.simpleQuery("SELECT 'lib/pq ping test';")
+	rows, err := cn.simpleQuery(";")
 	if err != nil {
 		return driver.ErrBadConn // https://golang.org/pkg/database/sql/driver/#Pinger
 	}

go19_test.go

@@ -55,6 +55,13 @@ func TestPing(t *testing.T) {
 	if rows.Err() != nil {
 		t.Fatal(err)
 	}
+	// Fail the transaction and make sure we can still ping.
+	if _, err := tx.Query("INVALID SQL"); err == nil {
+		t.Fatal("expected error")
+	}
+	if err := conn.PingContext(ctx); err != nil {
+		t.Fatal(err)
+	}
 	if err := tx.Rollback(); err != nil {
 		t.Fatal(err)
 	}