/*
* Copyright (C) 2007 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.io;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import java.io.EOFException;
import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.nio.CharBuffer;
import java.util.List;
/**
* Unit test for {@link CharStreams}.
*
* @author Chris Nokleberg
*/
public class CharStreamsTest extends IoTestCase {
private static final String TEXT
= "The quick brown fox jumped over the lazy dog.";
public void testToString() throws IOException {
assertEquals(TEXT, CharStreams.toString(new StringReader(TEXT)));
}
public void testReadLines() throws IOException {
List<String> lines = CharStreams.readLines(
new StringReader("a\nb\nc"));
assertEquals(ImmutableList.of("a", "b", "c"), lines);
}
public void testReadLines_withLineProcessor() throws IOException {
String text = "a\nb\nc";
// Test a LineProcessor that always returns false.
Reader r = new StringReader(text);
LineProcessor<Integer> alwaysFalse = new LineProcessor<Integer>() {
int seen;
@Override
public boolean processLine(String line) {
seen++;
return false;
}
@Override
public Integer getResult() {
return seen;
}
};
assertEquals("processLine was called more than once", 1,
CharStreams.readLines(r, alwaysFalse).intValue());
// Test a LineProcessor that always returns true.
r = new StringReader(text);
LineProcessor<Integer> alwaysTrue = new LineProcessor<Integer>() {
int seen;
@Override
public boolean processLine(String line) {
seen++;
return true;
}
@Override
public Integer getResult() {
return seen;
}
};
assertEquals("processLine was not called for all the lines", 3,
CharStreams.readLines(r, alwaysTrue).intValue());
// Test a LineProcessor that is conditional.
r = new StringReader(text);
final StringBuilder sb = new StringBuilder();
LineProcessor<Integer> conditional = new LineProcessor<Integer>() {
int seen;
@Override
public boolean processLine(String line) {
seen++;
sb.append(line);
return seen < 2;
}
@Override
public Integer getResult() {
return seen;
}
};
assertEquals(2, CharStreams.readLines(r, conditional).intValue());
assertEquals("ab", sb.toString());
}
public void testSkipFully_EOF() throws IOException {
Reader reader = new StringReader("abcde");
try {
CharStreams.skipFully(reader, 6);
fail("expected EOFException");
} catch (EOFException e) {
// expected
}
}
public void testSkipFully() throws IOException {
String testString = "abcdef";
Reader reader = new StringReader(testString);
assertEquals(testString.charAt(0), reader.read());
CharStreams.skipFully(reader, 1);
assertEquals(testString.charAt(2), reader.read());
CharStreams.skipFully(reader, 2);
assertEquals(testString.charAt(5), reader.read());
assertEquals(-1, reader.read());
}
public void testAsWriter() {
// Should wrap Appendable in a new object
Appendable plainAppendable = new StringBuilder();
Writer result = CharStreams.asWriter(plainAppendable);
assertNotSame(plainAppendable, result);
assertNotNull(result);
// A Writer should not be wrapped
Appendable secretlyAWriter = new StringWriter();
result = CharStreams.asWriter(secretlyAWriter);
assertSame(secretlyAWriter, result);
}
public void testCopy() throws IOException {
StringBuilder builder = new StringBuilder();
long copied = CharStreams.copy(new StringReader(ASCII), builder);
assertEquals(ASCII, builder.toString());
assertEquals(ASCII.length(), copied);
StringBuilder builder2 = new StringBuilder();
copied = CharStreams.copy(new StringReader(I18N), builder2);
assertEquals(I18N, builder2.toString());
assertEquals(I18N.length(), copied);
}
/**
* Test for Guava issue 1061: http://code.google.com/p/guava-libraries/issues/detail?id=1061
*
* <p>CharStreams.copy was failing to clear its CharBuffer after each read call, which effectively
* reduced the available size of the buffer each time a call to read didn't fill up the available
* space in the buffer completely. In general this is a performance problem since the buffer size
* is permanently reduced, but with certain Reader implementations it could also cause the buffer
* size to reach 0, causing an infinite loop.
*/
public void testCopyWithReaderThatDoesNotFillBuffer() throws IOException {
// need a long enough string for the buffer to hit 0 remaining before the copy completes
String string = Strings.repeat("0123456789", 100);
StringBuilder b = new StringBuilder();
// the main assertion of this test is here... the copy will fail if the buffer size goes down
// each time it is not filled completely
long copied = CharStreams.copy(newNonBufferFillingReader(new StringReader(string)), b);
assertEquals(string, b.toString());
assertEquals(string.length(), copied);
}
public void testExhaust_reader() throws IOException {
Reader reader = new StringReader(ASCII);
assertEquals(ASCII.length(), CharStreams.exhaust(reader));
assertEquals(-1, reader.read());
assertEquals(0, CharStreams.exhaust(reader));
Reader empty = new StringReader("");
assertEquals(0, CharStreams.exhaust(empty));
assertEquals(-1, empty.read());
}
public void testExhaust_readable() throws IOException {
CharBuffer buf = CharBuffer.wrap(ASCII);
assertEquals(ASCII.length(), CharStreams.exhaust(buf));
assertEquals(0, buf.remaining());
assertEquals(0, CharStreams.exhaust(buf));
CharBuffer empty = CharBuffer.wrap("");
assertEquals(0, CharStreams.exhaust(empty));
assertEquals(0, empty.remaining());
}
public void testNullWriter() throws Exception {
// create a null writer
Writer nullWriter = CharStreams.nullWriter();
// write to the writer
nullWriter.write('n');
String test = "Test string for NullWriter";
nullWriter.write(test);
nullWriter.write(test, 2, 10);
// nothing really to assert?
assertSame(CharStreams.nullWriter(), CharStreams.nullWriter());
}
/**
* Returns a reader wrapping the given reader that only reads half of the maximum number of
* characters that it could read in read(char[], int, int).
*/
private static Reader newNonBufferFillingReader(Reader reader) {
return new FilterReader(reader) {
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
// if a buffer isn't being cleared correctly, this method will eventually start being called
// with a len of 0 forever
if (len <= 0) {
fail("read called with a len of " + len);
}
// read fewer than the max number of chars to read
// shouldn't be a problem unless the buffer is shrinking each call
return in.read(cbuf, off, Math.max(len - 1024, 0));
}
};
}
}