1// Copyright 2019 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package iotest
6
7import (
8	"strings"
9	"testing"
10)
11
12var truncateWriterTests = []struct {
13	in    string
14	want  string
15	trunc int64
16	n     int
17}{
18	{"hello", "", -1, 5},
19	{"world", "", 0, 5},
20	{"abcde", "abc", 3, 5},
21	{"edcba", "edcba", 7, 5},
22}
23
24func TestTruncateWriter(t *testing.T) {
25	for _, tt := range truncateWriterTests {
26		buf := new(strings.Builder)
27		tw := TruncateWriter(buf, tt.trunc)
28		n, err := tw.Write([]byte(tt.in))
29		if err != nil {
30			t.Errorf("Unexpected error %v for\n\t%+v", err, tt)
31		}
32		if g, w := buf.String(), tt.want; g != w {
33			t.Errorf("got %q, expected %q", g, w)
34		}
35		if g, w := n, tt.n; g != w {
36			t.Errorf("read %d bytes, but expected to have read %d bytes for\n\t%+v", g, w, tt)
37		}
38	}
39}
40