without it, the tests try to open
$PWD/github.com/xddxdd/bird-lg-go/frontend/test_data/etc

diff --git a/frontend/bgpmap_test.go b/frontend/bgpmap_test.go
index 3450410..b830f26 100644
--- a/frontend/bgpmap_test.go
+++ b/frontend/bgpmap_test.go
@@ -3,15 +3,12 @@ package main
 import (
 	"io/ioutil"
 	"path"
-	"runtime"
 	"strings"
 	"testing"
 )
 
 func readDataFile(t *testing.T, filename string) string {
-	_, sourceName, _, _ := runtime.Caller(0)
-	projectRoot := path.Join(path.Dir(sourceName), "..")
-	dir := path.Join(projectRoot, filename)
+	dir := path.Join("..", filename)
 
 	data, err := ioutil.ReadFile(dir)
 	if err != nil {