/** * Copyright 2005 The Apache Software Foundation * * 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 org.apache.hadoop.io;import java.io.*;import java.util.Random;import junit.framework.TestCase;/** Unit tests for Writable. */public class TestWritable extends TestCase {  public TestWritable(String name) { super(name); }  /** Example class used in test cases below. */  public static class SimpleWritable implements Writable {    private static final Random RANDOM = new Random();    int state = RANDOM.nextInt();    public void write(DataOutput out) throws IOException {      out.writeInt(state);    }    public void readFields(DataInput in) throws IOException {      this.state = in.readInt();    }    public static SimpleWritable read(DataInput in) throws IOException {      SimpleWritable result = new SimpleWritable();      result.readFields(in);      return result;    }    /** Required by test code, below. */    public boolean equals(Object o) {      if (!(o instanceof SimpleWritable))        return false;      SimpleWritable other = (SimpleWritable)o;      return this.state == other.state;    }  }  /** Test 1: Check that SimpleWritable. */  public void testSimpleWritable() throws Exception {    testWritable(new SimpleWritable());  }  /** Utility method for testing writables. */  public static void testWritable(Writable before) throws Exception {      DataOutputBuffer dob = new DataOutputBuffer();      before.write(dob);      DataInputBuffer dib = new DataInputBuffer();      dib.reset(dob.getData(), dob.getLength());          Writable after = (Writable)before.getClass().newInstance();      after.readFields(dib);      assertEquals(before, after);  }	}