refactor file|path (#1409)

Co-authored-by: anqiansong <anqiansong@bytedance.com>

tools/goctl/util/pathx/path_test.go

@@ -0,0 +1,39 @@
+package pathx
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestReadLink(t *testing.T) {
+	dir, err := ioutil.TempDir("", "go-zero")
+	assert.Nil(t, err)
+	symLink := filepath.Join(dir, "test")
+	pwd, err := os.Getwd()
+	assertError(err, t)
+
+	err = os.Symlink(pwd, symLink)
+	assertError(err, t)
+
+	t.Run("linked", func(t *testing.T) {
+		ret, err := ReadLink(symLink)
+		assert.Nil(t, err)
+		assert.Equal(t, pwd, ret)
+	})
+
+	t.Run("unlink", func(t *testing.T) {
+		ret, err := ReadLink(pwd)
+		assert.Nil(t, err)
+		assert.Equal(t, pwd, ret)
+	})
+}
+
+func assertError(err error, t *testing.T) {
+	if err != nil {
+		t.Fatal(err)
+	}
+}