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package preimage
import (
"bytes"
"crypto/rand"
"errors"
"io"
"sync"
"testing"
"time"
"github.com/stretchr/testify/require"
)
type rawHint string
func (rh rawHint) Hint() string {
return string(rh)
}
func TestHints(t *testing.T) {
// Note: pretty much every string is valid communication:
// length, payload, 0. Worst case you run out of data, or allocate too much.
testHint := func(hints ...string) {
a, b := bidirectionalPipe()
var wg sync.WaitGroup
wg.Add(2)
go func() {
hw := NewHintWriter(a)
for _, h := range hints {
hw.Hint(rawHint(h))
}
wg.Done()
}()
got := make(chan string, len(hints))
go func() {
defer wg.Done()
hr := NewHintReader(b)
for i := 0; i < len(hints); i++ {
err := hr.NextHint(func(hint string) error {
got <- hint
return nil
})
if err == io.EOF {
break
}
require.NoError(t, err)
}
}()
if waitTimeout(&wg) {
t.Error("hint read/write stuck")
}
require.Equal(t, len(hints), len(got), "got all hints")
for _, h := range hints {
require.Equal(t, h, <-got, "hints match")
}
}
t.Run("empty hint", func(t *testing.T) {
testHint("")
})
t.Run("hello world", func(t *testing.T) {
testHint("hello world")
})
t.Run("zero byte", func(t *testing.T) {
testHint(string([]byte{0}))
})
t.Run("many zeroes", func(t *testing.T) {
testHint(string(make([]byte, 1000)))
})
t.Run("random data", func(t *testing.T) {
dat := make([]byte, 1000)
_, _ = rand.Read(dat[:])
testHint(string(dat))
})
t.Run("multiple hints", func(t *testing.T) {
testHint("give me header a", "also header b", "foo bar")
})
t.Run("unexpected EOF", func(t *testing.T) {
var buf bytes.Buffer
hw := NewHintWriter(&buf)
hw.Hint(rawHint("hello"))
_, _ = buf.Read(make([]byte, 1)) // read one byte so it falls short, see if it's detected
hr := NewHintReader(&buf)
err := hr.NextHint(func(hint string) error { return nil })
require.ErrorIs(t, err, io.ErrUnexpectedEOF)
})
t.Run("cb error", func(t *testing.T) {
a, b := bidirectionalPipe()
var wg sync.WaitGroup
wg.Add(2)
go func() {
hw := NewHintWriter(a)
hw.Hint(rawHint("one"))
hw.Hint(rawHint("two"))
wg.Done()
}()
go func() {
defer wg.Done()
hr := NewHintReader(b)
cbErr := errors.New("fail")
err := hr.NextHint(func(hint string) error { return cbErr })
require.ErrorIs(t, err, cbErr)
var readHint string
err = hr.NextHint(func(hint string) error {
readHint = hint
return nil
})
require.NoError(t, err)
require.Equal(t, readHint, "two")
}()
if waitTimeout(&wg) {
t.Error("read/write hint stuck")
}
})
}
// waitTimeout returns true iff wg.Wait timed out
func waitTimeout(wg *sync.WaitGroup) bool {
done := make(chan struct{})
go func() {
wg.Wait()
close(done)
}()
select {
case <-time.After(time.Second * 30):
return true
case <-done:
return false
}
}