1 files changed, 182 insertions, 0 deletions
diff --git a/src/internal/fuzz/minimize_test.go b/src/internal/fuzz/minimize_test.go
new file mode 100644
index 0000000..2db2633
--- /dev/null
+++ b/src/internal/fuzz/minimize_test.go
@@ -0,0 +1,182 @@
+// 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.
+
+//go:build darwin || freebsd || linux || windows
+
+package fuzz
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"reflect"
+	"testing"
+	"time"
+	"unicode"
+	"unicode/utf8"
+)
+
+func TestMinimizeInput(t *testing.T) {
+	type testcase struct {
+		name     string
+		fn       func(CorpusEntry) error
+		input    []any
+		expected []any
+	}
+	cases := []testcase{
+		{
+			name: "ones_byte",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].([]byte)
+				ones := 0
+				for _, v := range b {
+					if v == 1 {
+						ones++
+					}
+				}
+				if ones == 3 {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{[]byte{0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}},
+			expected: []any{[]byte{1, 1, 1}},
+		},
+		{
+			name: "single_bytes",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].([]byte)
+				if len(b) < 2 {
+					return nil
+				}
+				if len(b) == 2 && b[0] == 1 && b[1] == 2 {
+					return nil
+				}
+				return fmt.Errorf("bad %v", e.Values[0])
+			},
+			input:    []any{[]byte{1, 2, 3, 4, 5}},
+			expected: []any{[]byte("00")},
+		},
+		{
+			name: "set_of_bytes",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].([]byte)
+				if len(b) < 3 {
+					return nil
+				}
+				if bytes.Equal(b, []byte{0, 1, 2, 3, 4, 5}) || bytes.Equal(b, []byte{0, 4, 5}) {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{[]byte{0, 1, 2, 3, 4, 5}},
+			expected: []any{[]byte{0, 4, 5}},
+		},
+		{
+			name: "non_ascii_bytes",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].([]byte)
+				if len(b) == 3 {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{[]byte("ท")}, // ท is 3 bytes
+			expected: []any{[]byte("000")},
+		},
+		{
+			name: "ones_string",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].(string)
+				ones := 0
+				for _, v := range b {
+					if v == '1' {
+						ones++
+					}
+				}
+				if ones == 3 {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{"001010001000000000000000000"},
+			expected: []any{"111"},
+		},
+		{
+			name: "string_length",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].(string)
+				if len(b) == 5 {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{"zzzzz"},
+			expected: []any{"00000"},
+		},
+		{
+			name: "string_with_letter",
+			fn: func(e CorpusEntry) error {
+				b := e.Values[0].(string)
+				r, _ := utf8.DecodeRune([]byte(b))
+				if unicode.IsLetter(r) {
+					return fmt.Errorf("bad %v", e.Values[0])
+				}
+				return nil
+			},
+			input:    []any{"ZZZZZ"},
+			expected: []any{"A"},
+		},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			ws := &workerServer{
+				fuzzFn: func(e CorpusEntry) (time.Duration, error) {
+					return time.Second, tc.fn(e)
+				},
+			}
+			mem := &sharedMem{region: make([]byte, 100)} // big enough to hold value and header
+			vals := tc.input
+			success, err := ws.minimizeInput(context.Background(), vals, mem, minimizeArgs{})
+			if !success {
+				t.Errorf("minimizeInput did not succeed")
+			}
+			if err == nil {
+				t.Fatal("minimizeInput didn't provide an error")
+			}
+			if expected := fmt.Sprintf("bad %v", tc.expected[0]); err.Error() != expected {
+				t.Errorf("unexpected error: got %q, want %q", err, expected)
+			}
+			if !reflect.DeepEqual(vals, tc.expected) {
+				t.Errorf("unexpected results: got %v, want %v", vals, tc.expected)
+			}
+		})
+	}
+}
+
+// TestMinimizeFlaky checks that if we're minimizing an interesting
+// input and a flaky failure occurs, that minimization was not indicated
+// to be successful, and the error isn't returned (since it's flaky).
+func TestMinimizeFlaky(t *testing.T) {
+	ws := &workerServer{fuzzFn: func(e CorpusEntry) (time.Duration, error) {
+		return time.Second, errors.New("ohno")
+	}}
+	mem := &sharedMem{region: make([]byte, 100)} // big enough to hold value and header
+	vals := []any{[]byte(nil)}
+	args := minimizeArgs{KeepCoverage: make([]byte, len(coverageSnapshot))}
+	success, err := ws.minimizeInput(context.Background(), vals, mem, args)
+	if success {
+		t.Error("unexpected success")
+	}
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if count := mem.header().count; count != 1 {
+		t.Errorf("count: got %d, want 1", count)
+	}
+}