1 files changed, 48 insertions, 2 deletions
diff --git a/src/pkg/index/suffixarray/suffixarray_test.go b/src/pkg/index/suffixarray/suffixarray_test.go
index 023748500..9b4d89f42 100644
--- a/src/pkg/index/suffixarray/suffixarray_test.go
+++ b/src/pkg/index/suffixarray/suffixarray_test.go
@@ -6,7 +6,8 @@ package suffixarray
 
 import (
 	"bytes"
-	"regexp"
+	"exp/regexp"
+	"rand"
 	"sort"
 	"strings"
 	"testing"
@@ -213,7 +214,33 @@ func (a *index) at(i int) []byte    { return a.data[a.sa[i]:] }
 
 func testConstruction(t *testing.T, tc *testCase, x *Index) {
 	if !sort.IsSorted((*index)(x)) {
-		t.Errorf("testConstruction failed %s", tc.name)
+		t.Errorf("failed testConstruction %s", tc.name)
+	}
+}
+
+func equal(x, y *Index) bool {
+	if !bytes.Equal(x.data, y.data) {
+		return false
+	}
+	for i, j := range x.sa {
+		if j != y.sa[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func testSaveRestore(t *testing.T, tc *testCase, x *Index) {
+	var buf bytes.Buffer
+	if err := x.Write(&buf); err != nil {
+		t.Errorf("failed writing index %s (%s)", tc.name, err)
+	}
+	var y Index
+	if err := y.Read(&buf); err != nil {
+		t.Errorf("failed reading index %s (%s)", tc.name, err)
+	}
+	if !equal(x, &y) {
+		t.Errorf("restored index doesn't match saved index %s", tc.name)
 	}
 }
 
@@ -221,6 +248,7 @@ func TestIndex(t *testing.T) {
 	for _, tc := range testCases {
 		x := New([]byte(tc.source))
 		testConstruction(t, &tc, x)
+		testSaveRestore(t, &tc, x)
 		testLookups(t, &tc, x, 0)
 		testLookups(t, &tc, x, 1)
 		testLookups(t, &tc, x, 10)
@@ -228,3 +256,21 @@ func TestIndex(t *testing.T) {
 		testLookups(t, &tc, x, -1)
 	}
 }
+
+func BenchmarkSaveRestore(b *testing.B) {
+	b.StopTimer()
+	r := rand.New(rand.NewSource(0x5a77a1)) // guarantee always same sequence
+	data := make([]byte, 10<<20)            // 10MB index data
+	for i := range data {
+		data[i] = byte(r.Intn(256))
+	}
+	x := New(data)
+	testSaveRestore(nil, nil, x)                    // verify correctness
+	buf := bytes.NewBuffer(make([]byte, len(data))) // avoid frequent growing
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		x.Write(buf)
+		var y Index
+		y.Read(buf)
+	}
+}