package destination import ( "fmt" "io" "strings" "testing" "testing/iotest" "github.com/stretchr/testify/require" ) func TestHardLimitReader(t *testing.T) { const text = "hello world" r := iotest.OneByteReader( &hardLimitReader{ r: strings.NewReader(text), n: int64(len(text)), }, ) out, err := io.ReadAll(r) require.NoError(t, err) require.Equal(t, text, string(out)) } func TestHardLimitReaderFail(t *testing.T) { const text = "hello world" for bufSize := len(text) / 2; bufSize < len(text)*2; bufSize++ { t.Run(fmt.Sprintf("bufsize:%d", bufSize), func(t *testing.T) { r := &hardLimitReader{ r: iotest.DataErrReader(strings.NewReader(text)), n: int64(len(text)) - 1, } buf := make([]byte, bufSize) var err error for i := 0; err == nil && i < 1000; i++ { _, err = r.Read(buf) } require.Equal(t, ErrEntityTooLarge, err) }) } }