1 files changed, 179 insertions, 0 deletions
diff --git a/src/internal/fuzz/mutators_byteslice_test.go b/src/internal/fuzz/mutators_byteslice_test.go
new file mode 100644
index 0000000000..50a39a9a5b
--- /dev/null
+++ b/src/internal/fuzz/mutators_byteslice_test.go
@@ -0,0 +1,179 @@
+// Copyright 2021 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 fuzz
+
+import (
+	"bytes"
+	"testing"
+)
+
+type mockRand struct {
+	counter int
+	b       bool
+}
+
+func (mr *mockRand) uint32() uint32 {
+	c := mr.counter
+	mr.counter++
+	return uint32(c)
+}
+
+func (mr *mockRand) intn(n int) int {
+	c := mr.counter
+	mr.counter++
+	return c % n
+}
+
+func (mr *mockRand) uint32n(n uint32) uint32 {
+	c := mr.counter
+	mr.counter++
+	return uint32(c) % n
+}
+
+func (mr *mockRand) exp2() int {
+	c := mr.counter
+	mr.counter++
+	return c
+}
+
+func (mr *mockRand) bool() bool {
+	b := mr.b
+	mr.b = !mr.b
+	return b
+}
+
+func (mr *mockRand) save(*uint64, *uint64) {
+	panic("unimplemented")
+}
+
+func (mr *mockRand) restore(uint64, uint64) {
+	panic("unimplemented")
+}
+
+func TestByteSliceMutators(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		mutator  func(*mutator, []byte) []byte
+		input    []byte
+		expected []byte
+	}{
+		{
+			name:     "byteSliceRemoveBytes",
+			mutator:  byteSliceRemoveBytes,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{4},
+		},
+		{
+			name:     "byteSliceInsertRandomBytes",
+			mutator:  byteSliceInsertRandomBytes,
+			input:    make([]byte, 4, 8),
+			expected: []byte{3, 4, 5, 0, 0, 0, 0},
+		},
+		{
+			name:     "byteSliceDuplicateBytes",
+			mutator:  byteSliceDuplicateBytes,
+			input:    append(make([]byte, 0, 13), []byte{1, 2, 3, 4}...),
+			expected: []byte{1, 1, 2, 3, 4, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceOverwriteBytes",
+			mutator:  byteSliceOverwriteBytes,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{1, 1, 3, 4},
+		},
+		{
+			name:     "byteSliceBitFlip",
+			mutator:  byteSliceBitFlip,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{3, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceXORByte",
+			mutator:  byteSliceXORByte,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{3, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceSwapByte",
+			mutator:  byteSliceSwapByte,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{2, 1, 3, 4},
+		},
+		{
+			name:     "byteSliceArithmeticUint8",
+			mutator:  byteSliceArithmeticUint8,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{255, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceArithmeticUint16",
+			mutator:  byteSliceArithmeticUint16,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{1, 3, 3, 4},
+		},
+		{
+			name:     "byteSliceArithmeticUint32",
+			mutator:  byteSliceArithmeticUint32,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{2, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceArithmeticUint64",
+			mutator:  byteSliceArithmeticUint64,
+			input:    []byte{1, 2, 3, 4, 5, 6, 7, 8},
+			expected: []byte{2, 2, 3, 4, 5, 6, 7, 8},
+		},
+		{
+			name:     "byteSliceOverwriteInterestingUint8",
+			mutator:  byteSliceOverwriteInterestingUint8,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{255, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceOverwriteInterestingUint16",
+			mutator:  byteSliceOverwriteInterestingUint16,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{255, 127, 3, 4},
+		},
+		{
+			name:     "byteSliceOverwriteInterestingUint32",
+			mutator:  byteSliceOverwriteInterestingUint32,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{250, 0, 0, 250},
+		},
+		{
+			name:     "byteSliceInsertConstantBytes",
+			mutator:  byteSliceInsertConstantBytes,
+			input:    append(make([]byte, 0, 8), []byte{1, 2, 3, 4}...),
+			expected: []byte{3, 3, 3, 1, 2, 3, 4},
+		},
+		{
+			name:     "byteSliceOverwriteConstantBytes",
+			mutator:  byteSliceOverwriteConstantBytes,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{3, 3, 3, 4},
+		},
+		{
+			name:     "byteSliceShuffleBytes",
+			mutator:  byteSliceShuffleBytes,
+			input:    []byte{1, 2, 3, 4},
+			expected: []byte{2, 3, 1, 4},
+		},
+		{
+			name:     "byteSliceSwapBytes",
+			mutator:  byteSliceSwapBytes,
+			input:    append(make([]byte, 0, 9), []byte{1, 2, 3, 4}...),
+			expected: []byte{2, 1, 3, 4},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			m := &mutator{r: &mockRand{}}
+			b := tc.mutator(m, tc.input)
+			if !bytes.Equal(b, tc.expected) {
+				t.Errorf("got %x, want %x", b, tc.expected)
+			}
+		})
+	}
+}