Move benchmark functionality and remove caller function

diffmatchpatch/benchutil_test.go

diff --git a/diffmatchpatch/benchutil_test.go b/diffmatchpatch/benchutil_test.go
new file mode 100644
index 0000000..85f273b
--- /dev/null
+++ b/diffmatchpatch/benchutil_test.go
@@ -0,0 +1,26 @@
+// Copyright (c) 2012-2016 The go-diff authors. All rights reserved.
+// https://github.com/sergi/go-diff
+// See the included LICENSE file for license details.
+//
+// go-diff is a Go implementation of Google's Diff, Match, and Patch library
+// Original library is Copyright (c) 2006 Google Inc.
+// http://code.google.com/p/google-diff-match-patch/
+
+package diffmatchpatch
+
+import (
+	"io/ioutil"
+)
+
+func speedtestTexts() (s1 string, s2 string) {
+	d1, err := ioutil.ReadFile("../testdata/speedtest1.txt")
+	if err != nil {
+		panic(err)
+	}
+	d2, err := ioutil.ReadFile("../testdata/speedtest2.txt")
+	if err != nil {
+		panic(err)
+	}
+
+	return string(d1), string(d2)
+}

diffmatchpatch/diffmatchpatch_test.go

diff --git a/diffmatchpatch/diffmatchpatch_test.go b/diffmatchpatch/diffmatchpatch_test.go
index 0d843ad..830e4bd 100644
--- a/diffmatchpatch/diffmatchpatch_test.go
+++ b/diffmatchpatch/diffmatchpatch_test.go
@@ -10,38 +10,11 @@
 
 import (
 	"fmt"
-	"io/ioutil"
-	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
-func caller() string {
-	_, _, line, ok := runtime.Caller(2)
-	if !ok {
-		return ""
-	}
-
-	return fmt.Sprintf("at line %d ", line)
-}
-
-func readFile(filepath string) string {
-	data, err := ioutil.ReadFile(filepath)
-	if err != nil {
-		panic(err)
-	}
-
-	return string(data)
-}
-
-func speedtestTexts() (s1 string, s2 string) {
-	s1 = readFile("../testdata/speedtest1.txt")
-	s2 = readFile("../testdata/speedtest2.txt")
-
-	return s1, s2
-}
-
 func TestRunesIndexOf(t *testing.T) {
 	type TestCase struct {
 		Pattern string