src/cmd/go/testdata/script/test_fuzz_minimize_dirty_cov.txt

# Test that minimization doesn't use dirty coverage snapshots when it
# is unable to actually minimize the input. We do this by checking that
# an expected value appears in the cache. If a dirty coverage map is used
# (i.e. the coverage map generated during the last minimization step,
# rather than the map provided with the initial input) then this value
# is unlikely to appear in the cache, since the map generated during
# the last minimization step should not increase the coverage.

[short] skip
[!fuzz-instrumented] skip

env GOCACHE=$WORK/gocache
go test -fuzz=FuzzCovMin -fuzztime=500000x -test.fuzzcachedir=$GOCACHE/fuzz
go run check_file/main.go $GOCACHE/fuzz/FuzzCovMin ab

-- go.mod --
module test

-- covmin_test.go --
package covmin

import "testing"

func FuzzCovMin(f *testing.F) {
	f.Add([]byte("aa"))
	f.Fuzz(func(t *testing.T, data []byte) {
		if len(data) == 2 && data[0] == 'a' && data[1] == 'b' {
			return
		}
	})
}

-- check_file/main.go --
package main

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
)

func checkFile(name, expected string) (bool, error) {
	data, err := os.ReadFile(name)
	if err != nil {
		return false, err
	}
	for _, line := range bytes.Split(data, []byte("\n")) {
		m := valRe.FindSubmatch(line)
		if m == nil {
			continue
		}
		fmt.Println(strconv.Unquote(string(m[1])))
		if s, err := strconv.Unquote(string(m[1])); err != nil {
			return false, err
		} else if s == expected {
			return true, nil
		}
	}
	return false, nil
}

var valRe = regexp.MustCompile(`^\[\]byte\(([^)]+)\)$`)

func main() {
	dir, expected := os.Args[1], os.Args[2]
	ents, err := os.ReadDir(dir)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	for _, ent := range ents {
		name := filepath.Join(dir, ent.Name())
		if good, err := checkFile(name, expected); err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		} else if good {
			os.Exit(0)
		}
	}
	fmt.Fprintln(os.Stderr, "input over minimized")
	os.Exit(1)
}