1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18package tests.support;
19
20import java.io.FilterReader;
21import java.io.IOException;
22import java.io.Reader;
23
24/**
25 * A reader that always throws after a predetermined number of bytes have been
26 * read.
27 */
28public class ThrowingReader extends FilterReader {
29
30    private int total = 0;
31    private int throwAt;
32
33    public ThrowingReader(Reader in, int throwAt) {
34        super(in);
35        this.throwAt = throwAt;
36    }
37
38    @Override public int read() throws IOException {
39        explodeIfNecessary();
40        int result = super.read();
41        total++;
42        return result;
43    }
44
45    @Override public int read(char[] buf, int offset, int count)
46            throws IOException {
47        explodeIfNecessary();
48
49        if (total < throwAt) {
50            count = Math.min(count, (throwAt - total));
51        }
52
53        int returned = super.read(buf, offset, count);
54        total += returned;
55        return returned;
56    }
57
58    private void explodeIfNecessary() throws IOException {
59        if (total == throwAt) {
60            throwAt = Integer.MAX_VALUE;
61            throw new IOException();
62        }
63    }
64}
65