Commons IO example source code file (NullReaderTest.java)

This example Commons IO source code file (NullReaderTest.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons IO tags/keywords

check, exception, exception, io, ioexception, ioexception, mark, override, read, read, reader, should, skip, testnullreader, testnullreader

The Commons IO NullReaderTest.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.commons.io.input;

import java.io.EOFException;
import java.io.IOException;
import java.io.Reader;

import junit.framework.TestCase;

/**
 * JUnit Test Case for {@link NullReader}.
 *
 * @version $Id: NullReaderTest.java 1003571 2010-10-01 16:26:35Z sebb $
 */
public class NullReaderTest extends TestCase {

    /** Constructor */
    public NullReaderTest(String name) {
        super(name);
    }

    /** Set up */
    @Override
    protected void setUp() throws Exception {
        super.setUp();
    }

    /** Tear Down */
    @Override
    protected void tearDown() throws Exception {
        super.tearDown();
    }

    /**
     * Test <code>available() method.
     */
    public void testRead() throws Exception {
        int size = 5;
        TestNullReader reader = new TestNullReader(size);
        for (int i = 0; i < size; i++) {
            assertEquals("Check Value [" + i + "]", i, reader.read());
        }

        // Check End of File
        assertEquals("End of File", -1, reader.read());

        // Test reading after the end of file
        try {
            int result = reader.read();
            fail("Should have thrown an IOException, value=[" + result + "]");
        } catch (IOException e) {
            assertEquals("Read after end of file", e.getMessage());
        }

        // Close - should reset
        reader.close();
        assertEquals("Available after close", 0, reader.getPosition());
    }

    /**
     * Test <code>read(char[]) method.
     */
    public void testReadCharArray() throws Exception {
        char[] chars = new char[10];
        Reader reader = new TestNullReader(15);

        // Read into array
        int count1 = reader.read(chars);
        assertEquals("Read 1", chars.length, count1);
        for (int i = 0; i < count1; i++) {
            assertEquals("Check Chars 1", i, chars[i]);
        }

        // Read into array
        int count2 = reader.read(chars);
        assertEquals("Read 2", 5, count2);
        for (int i = 0; i < count2; i++) {
            assertEquals("Check Chars 2", count1 + i, chars[i]);
        }

        // End of File
        int count3 = reader.read(chars);
        assertEquals("Read 3 (EOF)", -1, count3);

        // Test reading after the end of file
        try {
            int count4 = reader.read(chars);
            fail("Should have thrown an IOException, value=[" + count4 + "]");
        } catch (IOException e) {
            assertEquals("Read after end of file", e.getMessage());
        }

        // reset by closing
        reader.close();
    
        // Read into array using offset & length
        int offset = 2;
        int lth    = 4;
        int count5 = reader.read(chars, offset, lth);
        assertEquals("Read 5", lth, count5);
        for (int i = offset; i < lth; i++) {
            assertEquals("Check Chars 3", i, chars[i]);
        }
    }

    /**
     * Test when configured to throw an EOFException at the end of file
     * (rather than return -1).
     */
    public void testEOFException() throws Exception {
        Reader reader = new TestNullReader(2, false, true);
        assertEquals("Read 1",  0, reader.read());
        assertEquals("Read 2",  1, reader.read());
        try {
            int result = reader.read();
            fail("Should have thrown an EOFException, value=[" + result + "]");
        } catch (EOFException e) {
            // expected
        }
    }

    /**
     * Test <code>mark() and reset() methods.
     */
    public void testMarkAndReset() throws Exception {
        int position = 0;
        int readlimit = 10;
        Reader reader = new TestNullReader(100, true, false);
        
        assertTrue("Mark Should be Supported", reader.markSupported());

        // No Mark
        try {
            reader.reset();
            fail("Read limit exceeded, expected IOException ");
        } catch (IOException e) {
            assertEquals("No Mark IOException message",
                         "No position has been marked",
                         e.getMessage());
        }

        for (; position < 3; position++) {
            assertEquals("Read Before Mark [" + position +"]",  position, reader.read());
        }

        // Mark
        reader.mark(readlimit);

        // Read further
        for (int i = 0; i < 3; i++) {
            assertEquals("Read After Mark [" + i +"]",  (position + i), reader.read());
        }

        // Reset
        reader.reset();

        // Read From marked position
        for (int i = 0; i < readlimit + 1; i++) {
            assertEquals("Read After Reset [" + i +"]",  (position + i), reader.read());
        }

        // Reset after read limit passed
        try {
            reader.reset();
            fail("Read limit exceeded, expected IOException ");
        } catch (IOException e) {
            assertEquals("Read limit IOException message",
                         "Marked position [" + position
                         + "] is no longer valid - passed the read limit ["
                         + readlimit + "]",
                         e.getMessage());
        }
    }

    /**
     * Test <code>mark() not supported.
     */
    public void testMarkNotSupported() throws Exception {
        Reader reader = new TestNullReader(100, false, true);
        assertFalse("Mark Should NOT be Supported", reader.markSupported());

        try {
            reader.mark(5);
            fail("mark() should throw UnsupportedOperationException");
        } catch (UnsupportedOperationException e) {
            assertEquals("mark() error message",  "Mark not supported", e.getMessage());
        }

        try {
            reader.reset();
            fail("reset() should throw UnsupportedOperationException");
        } catch (UnsupportedOperationException e) {
            assertEquals("reset() error message",  "Mark not supported", e.getMessage());
        }
    }

    /**
     * Test <code>skip() method.
     */
   public void testSkip() throws Exception {
        Reader reader = new TestNullReader(10, true, false);
        assertEquals("Read 1", 0, reader.read());
        assertEquals("Read 2", 1, reader.read());
        assertEquals("Skip 1", 5, reader.skip(5));
        assertEquals("Read 3", 7, reader.read());
        assertEquals("Skip 2", 2, reader.skip(5)); // only 2 left to skip
        assertEquals("Skip 3 (EOF)", -1, reader.skip(5)); // End of file
        try {
            reader.skip(5); //
            fail("Expected IOException for skipping after end of file");
        } catch (IOException e) {
            assertEquals("Skip after EOF IOException message",
                    "Skip after end of file",
                    e.getMessage());
        }
    }


    // ------------- Test NullReader implementation -------------

    private static final class TestNullReader extends NullReader {
        public TestNullReader(int size) {
            super(size);
        }
        public TestNullReader(int size, boolean markSupported, boolean throwEofException) {
            super(size, markSupported, throwEofException);
        }
        @Override
        protected int processChar() {
            return ((int)getPosition() - 1);
        }
        @Override
        protected void processChars(char[] chars, int offset, int length) {
            int startPos = (int)getPosition() - length;
            for (int i = offset; i < length; i++) {
                chars[i] = (char)(startPos + i);
            }
        }
        
    }
}