1 files changed, 262 insertions, 0 deletions
diff --git a/src/bytes/compare_test.go b/src/bytes/compare_test.go
new file mode 100644
index 0000000..a595d57
--- /dev/null
+++ b/src/bytes/compare_test.go
@@ -0,0 +1,262 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bytes_test
+
+import (
+	. "bytes"
+	"internal/testenv"
+	"testing"
+)
+
+var compareTests = []struct {
+	a, b []byte
+	i    int
+}{
+	{[]byte(""), []byte(""), 0},
+	{[]byte("a"), []byte(""), 1},
+	{[]byte(""), []byte("a"), -1},
+	{[]byte("abc"), []byte("abc"), 0},
+	{[]byte("abd"), []byte("abc"), 1},
+	{[]byte("abc"), []byte("abd"), -1},
+	{[]byte("ab"), []byte("abc"), -1},
+	{[]byte("abc"), []byte("ab"), 1},
+	{[]byte("x"), []byte("ab"), 1},
+	{[]byte("ab"), []byte("x"), -1},
+	{[]byte("x"), []byte("a"), 1},
+	{[]byte("b"), []byte("x"), -1},
+	// test runtime·memeq's chunked implementation
+	{[]byte("abcdefgh"), []byte("abcdefgh"), 0},
+	{[]byte("abcdefghi"), []byte("abcdefghi"), 0},
+	{[]byte("abcdefghi"), []byte("abcdefghj"), -1},
+	{[]byte("abcdefghj"), []byte("abcdefghi"), 1},
+	// nil tests
+	{nil, nil, 0},
+	{[]byte(""), nil, 0},
+	{nil, []byte(""), 0},
+	{[]byte("a"), nil, 1},
+	{nil, []byte("a"), -1},
+}
+
+func TestCompare(t *testing.T) {
+	for _, tt := range compareTests {
+		numShifts := 16
+		buffer := make([]byte, len(tt.b)+numShifts)
+		// vary the input alignment of tt.b
+		for offset := 0; offset <= numShifts; offset++ {
+			shiftedB := buffer[offset : len(tt.b)+offset]
+			copy(shiftedB, tt.b)
+			cmp := Compare(tt.a, shiftedB)
+			if cmp != tt.i {
+				t.Errorf(`Compare(%q, %q), offset %d = %v; want %v`, tt.a, tt.b, offset, cmp, tt.i)
+			}
+		}
+	}
+}
+
+func TestCompareIdenticalSlice(t *testing.T) {
+	var b = []byte("Hello Gophers!")
+	if Compare(b, b) != 0 {
+		t.Error("b != b")
+	}
+	if Compare(b, b[:1]) != 1 {
+		t.Error("b > b[:1] failed")
+	}
+}
+
+func TestCompareBytes(t *testing.T) {
+	lengths := make([]int, 0) // lengths to test in ascending order
+	for i := 0; i <= 128; i++ {
+		lengths = append(lengths, i)
+	}
+	lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
+
+	if !testing.Short() || testenv.Builder() != "" {
+		lengths = append(lengths, 65535, 65536, 65537, 99999)
+	}
+
+	n := lengths[len(lengths)-1]
+	a := make([]byte, n+1)
+	b := make([]byte, n+1)
+	for _, len := range lengths {
+		// randomish but deterministic data. No 0 or 255.
+		for i := 0; i < len; i++ {
+			a[i] = byte(1 + 31*i%254)
+			b[i] = byte(1 + 31*i%254)
+		}
+		// data past the end is different
+		for i := len; i <= n; i++ {
+			a[i] = 8
+			b[i] = 9
+		}
+		cmp := Compare(a[:len], b[:len])
+		if cmp != 0 {
+			t.Errorf(`CompareIdentical(%d) = %d`, len, cmp)
+		}
+		if len > 0 {
+			cmp = Compare(a[:len-1], b[:len])
+			if cmp != -1 {
+				t.Errorf(`CompareAshorter(%d) = %d`, len, cmp)
+			}
+			cmp = Compare(a[:len], b[:len-1])
+			if cmp != 1 {
+				t.Errorf(`CompareBshorter(%d) = %d`, len, cmp)
+			}
+		}
+		for k := 0; k < len; k++ {
+			b[k] = a[k] - 1
+			cmp = Compare(a[:len], b[:len])
+			if cmp != 1 {
+				t.Errorf(`CompareAbigger(%d,%d) = %d`, len, k, cmp)
+			}
+			b[k] = a[k] + 1
+			cmp = Compare(a[:len], b[:len])
+			if cmp != -1 {
+				t.Errorf(`CompareBbigger(%d,%d) = %d`, len, k, cmp)
+			}
+			b[k] = a[k]
+		}
+	}
+}
+
+func TestEndianBaseCompare(t *testing.T) {
+	// This test compares byte slices that are almost identical, except one
+	// difference that for some j, a[j]>b[j] and a[j+1]<b[j+1]. If the implementation
+	// compares large chunks with wrong endianness, it gets wrong result.
+	// no vector register is larger than 512 bytes for now
+	const maxLength = 512
+	a := make([]byte, maxLength)
+	b := make([]byte, maxLength)
+	// randomish but deterministic data. No 0 or 255.
+	for i := 0; i < maxLength; i++ {
+		a[i] = byte(1 + 31*i%254)
+		b[i] = byte(1 + 31*i%254)
+	}
+	for i := 2; i <= maxLength; i <<= 1 {
+		for j := 0; j < i-1; j++ {
+			a[j] = b[j] - 1
+			a[j+1] = b[j+1] + 1
+			cmp := Compare(a[:i], b[:i])
+			if cmp != -1 {
+				t.Errorf(`CompareBbigger(%d,%d) = %d`, i, j, cmp)
+			}
+			a[j] = b[j] + 1
+			a[j+1] = b[j+1] - 1
+			cmp = Compare(a[:i], b[:i])
+			if cmp != 1 {
+				t.Errorf(`CompareAbigger(%d,%d) = %d`, i, j, cmp)
+			}
+			a[j] = b[j]
+			a[j+1] = b[j+1]
+		}
+	}
+}
+
+func BenchmarkCompareBytesEqual(b *testing.B) {
+	b1 := []byte("Hello Gophers!")
+	b2 := []byte("Hello Gophers!")
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+}
+
+func BenchmarkCompareBytesToNil(b *testing.B) {
+	b1 := []byte("Hello Gophers!")
+	var b2 []byte
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 1 {
+			b.Fatal("b1 > b2 failed")
+		}
+	}
+}
+
+func BenchmarkCompareBytesEmpty(b *testing.B) {
+	b1 := []byte("")
+	b2 := b1
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+}
+
+func BenchmarkCompareBytesIdentical(b *testing.B) {
+	b1 := []byte("Hello Gophers!")
+	b2 := b1
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+}
+
+func BenchmarkCompareBytesSameLength(b *testing.B) {
+	b1 := []byte("Hello Gophers!")
+	b2 := []byte("Hello, Gophers")
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != -1 {
+			b.Fatal("b1 < b2 failed")
+		}
+	}
+}
+
+func BenchmarkCompareBytesDifferentLength(b *testing.B) {
+	b1 := []byte("Hello Gophers!")
+	b2 := []byte("Hello, Gophers!")
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != -1 {
+			b.Fatal("b1 < b2 failed")
+		}
+	}
+}
+
+func BenchmarkCompareBytesBigUnaligned(b *testing.B) {
+	b.StopTimer()
+	b1 := make([]byte, 0, 1<<20)
+	for len(b1) < 1<<20 {
+		b1 = append(b1, "Hello Gophers!"...)
+	}
+	b2 := append([]byte("hello"), b1...)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2[len("hello"):]) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+	b.SetBytes(int64(len(b1)))
+}
+
+func BenchmarkCompareBytesBig(b *testing.B) {
+	b.StopTimer()
+	b1 := make([]byte, 0, 1<<20)
+	for len(b1) < 1<<20 {
+		b1 = append(b1, "Hello Gophers!"...)
+	}
+	b2 := append([]byte{}, b1...)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+	b.SetBytes(int64(len(b1)))
+}
+
+func BenchmarkCompareBytesBigIdentical(b *testing.B) {
+	b.StopTimer()
+	b1 := make([]byte, 0, 1<<20)
+	for len(b1) < 1<<20 {
+		b1 = append(b1, "Hello Gophers!"...)
+	}
+	b2 := b1
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		if Compare(b1, b2) != 0 {
+			b.Fatal("b1 != b2")
+		}
+	}
+	b.SetBytes(int64(len(b1)))
+}