guava-tests/test/com/google/common/io/MultiReaderTest.java

/*
 * Copyright (C) 2008 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.collect.ImmutableList;

import junit.framework.TestCase;

import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

/**
 * @author ricebin
 */
public class MultiReaderTest extends TestCase {

  public void testOnlyOneOpen() throws Exception {
    String testString = "abcdefgh";
    final CharSource source = newCharSource(testString);
    final int[] counter = new int[1];
    CharSource reader = new CharSource() {
      @Override
      public Reader openStream() throws IOException {
        if (counter[0]++ != 0) {
          throw new IllegalStateException("More than one source open");
        }
        return new FilterReader(source.openStream()) {
          @Override public void close() throws IOException {
            super.close();
            counter[0]--;
          }
        };
      }
    };
    Reader joinedReader = CharSource.concat(reader, reader, reader).openStream();
    String result = CharStreams.toString(joinedReader);
    assertEquals(testString.length() * 3, result.length());
  }

  public void testReady() throws Exception {
    CharSource source = newCharSource("a");
    Iterable<? extends CharSource> list = ImmutableList.of(source, source);
    Reader joinedReader = CharSource.concat(list).openStream();

    assertTrue(joinedReader.ready());
    assertEquals('a', joinedReader.read());
    assertEquals('a', joinedReader.read());
    assertEquals(-1, joinedReader.read());
    assertFalse(joinedReader.ready());    
  }

  public void testSimple() throws Exception {
    String testString = "abcdefgh";
    CharSource source = newCharSource(testString);
    Reader joinedReader = CharSource.concat(source, source).openStream();

    String expectedString = testString + testString;
    assertEquals(expectedString, CharStreams.toString(joinedReader));
  }

  
  private static CharSource newCharSource(final String text) {
    return new CharSource() {
      @Override
      public Reader openStream() {
        return new StringReader(text);
      }
    };
  }

  public void testSkip() throws Exception {
    String begin = "abcde";
    String end = "fghij";
    Reader joinedReader =
        CharSource.concat(newCharSource(begin), newCharSource(end)).openStream();

    String expected = begin + end;
    assertEquals(expected.charAt(0), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(2), joinedReader.read());
    CharStreams.skipFully(joinedReader, 4);
    assertEquals(expected.charAt(7), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(9), joinedReader.read());
    assertEquals(-1, joinedReader.read());
  }
  
  public void testSkipZero() throws Exception {
    CharSource source = newCharSource("a");
    Iterable<CharSource> list = ImmutableList.of(source, source);
    Reader joinedReader = CharSource.concat(list).openStream();

    assertEquals(0, joinedReader.skip(0));
    assertEquals('a', joinedReader.read());
  }

}