diff --git a/main_test.go b/main_test.go
index bf45536..49da8eb 100644
--- a/main_test.go
+++ b/main_test.go
@@ -23,6 +23,7 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"unicode/utf8"
 
 	"github.com/sergi/go-diff/diffmatchpatch"
 )
@@ -196,6 +197,25 @@ func TestMinimalError(t *testing.T) {
 // TODO(sbarzowski) test pretty errors once they are stable-ish
 // probably "golden" pattern is the right one for that
 
+func removeExcessiveWhitespace(s string) string {
+	var buf bytes.Buffer
+	separated := true
+	for i, w := 0, 0; i < len(s); i += w {
+		runeValue, width := utf8.DecodeRuneInString(s[i:])
+		if runeValue == '\n' || runeValue == ' ' {
+			if !separated {
+				buf.WriteString(" ")
+				separated = true
+			}
+		} else {
+			buf.WriteRune(runeValue)
+			separated = false
+		}
+		w = width
+	}
+	return buf.String()
+}
+
 func TestCustomImporter(t *testing.T) {
 	vm := MakeVM()
 	vm.Importer(&MemoryImporter{