secure/precis: add test for multiple Transform calls.
Change-Id: Iea031eef1f29153bbe158a5287238b81fd3ee8af
Reviewed-on: https://go-review.googlesource.com/47871
Reviewed-by: Nigel Tao <nigeltao@golang.org>
Run-TryBot: Nigel Tao <nigeltao@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/secure/precis/enforce_test.go b/secure/precis/enforce_test.go
index 0cb5b60..d36a980 100644
--- a/secure/precis/enforce_test.go
+++ b/secure/precis/enforce_test.go
@@ -5,12 +5,14 @@
package precis
import (
+ "bytes"
"fmt"
"reflect"
"testing"
"golang.org/x/text/internal/testtext"
"golang.org/x/text/secure/bidirule"
+ "golang.org/x/text/transform"
)
type testCase struct {
@@ -320,3 +322,72 @@
t.Errorf("got %f allocs, want 0", n)
}
}
+
+func min(a, b int) int {
+ if a < b {
+ return a
+ }
+ return b
+}
+
+// TestTransformerShortBuffers tests that the precis.Transformer implements the
+// spirit, not just the letter (the method signatures), of the
+// transform.Transformer interface.
+//
+// In particular, it tests that, if one or both of the dst or src buffers are
+// short, so that multiple Transform calls are required to complete the overall
+// transformation, the end result is identical to one Transform call with
+// sufficiently long buffers.
+func TestTransformerShortBuffers(t *testing.T) {
+ srcUnit := []byte("a\u0300cce\u0301nts") // NFD normalization form.
+ wantUnit := []byte("àccénts") // NFC normalization form.
+ src := bytes.Repeat(srcUnit, 16)
+ want := bytes.Repeat(wantUnit, 16)
+ const long = 4096
+ dst := make([]byte, long)
+
+ // 5, 7, 9, 11, 13, 16 and 17 are all pair-wise co-prime, which means that
+ // slicing the dst and src buffers into 5, 7, 13 and 17 byte chunks will
+ // fall at different places inside the repeated srcUnit's and wantUnit's.
+ if len(srcUnit) != 11 || len(wantUnit) != 9 || len(src) > long || len(want) > long {
+ t.Fatal("inconsistent lengths")
+ }
+
+ tr := NewFreeform().NewTransformer()
+ for _, deltaD := range []int{5, 7, 13, 17, long} {
+ loop:
+ for _, deltaS := range []int{5, 7, 13, 17, long} {
+ tr.Reset()
+ d0 := 0
+ s0 := 0
+ for {
+ d1 := min(len(dst), d0+deltaD)
+ s1 := min(len(src), s0+deltaS)
+ nDst, nSrc, err := tr.Transform(dst[d0:d1:d1], src[s0:s1:s1], s1 == len(src))
+ d0 += nDst
+ s0 += nSrc
+ if err == nil {
+ break
+ }
+ if err == transform.ErrShortDst || err == transform.ErrShortSrc {
+ continue
+ }
+ t.Errorf("deltaD=%d, deltaS=%d: %v", deltaD, deltaS, err)
+ continue loop
+ }
+ if s0 != len(src) {
+ t.Errorf("deltaD=%d, deltaS=%d: s0: got %d, want %d", deltaD, deltaS, s0, len(src))
+ continue
+ }
+ if d0 != len(want) {
+ t.Errorf("deltaD=%d, deltaS=%d: d0: got %d, want %d", deltaD, deltaS, d0, len(want))
+ continue
+ }
+ got := dst[:d0]
+ if !bytes.Equal(got, want) {
+ t.Errorf("deltaD=%d, deltaS=%d:\ngot %q\nwant %q", deltaD, deltaS, got, want)
+ continue
+ }
+ }
+ }
+}
