Commons IO example source code file (NullInputStreamTest.java)

This example Commons IO source code file (NullInputStreamTest.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, inputstream, io, ioexception, ioexception, mark, override, read, read, should, skip, testnullinputstream, testnullinputstream

The Commons IO NullInputStreamTest.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.InputStream;

import junit.framework.TestCase;

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

    /** Constructor */
    public NullInputStreamTest(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;
        InputStream input = new TestNullInputStream(size);
        for (int i = 0; i < size; i++) {
            assertEquals("Check Size [" + i + "]", (size - i), input.available());
            assertEquals("Check Value [" + i + "]", i, input.read());
        }
        assertEquals("Available after contents all read", 0, input.available());

        // Check availbale is zero after End of file
        assertEquals("End of File", -1, input.read());
        assertEquals("Available after End of File", 0, input.available());

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

        // Close - should reset
        input.close();
        assertEquals("Available after close", size, input.available());
    }

    /**
     * Test <code>read(byte[]) method.
     */
    public void testReadByteArray() throws Exception {
        byte[] bytes = new byte[10];
        InputStream input = new TestNullInputStream(15);

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

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

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

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

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

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

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

        // No Mark
        try {
            input.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, input.read());
        }

        // Mark
        input.mark(readlimit);

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

        // Reset
        input.reset();

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

        // Reset after read limit passed
        try {
            input.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 {
        InputStream input = new TestNullInputStream(100, false, true);
        assertFalse("Mark Should NOT be Supported", input.markSupported());

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

        try {
            input.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 {
        InputStream input = new TestNullInputStream(10, true, false);
        assertEquals("Read 1", 0, input.read());
        assertEquals("Read 2", 1, input.read());
        assertEquals("Skip 1", 5, input.skip(5));
        assertEquals("Read 3", 7, input.read());
        assertEquals("Skip 2", 2, input.skip(5)); // only 2 left to skip
        assertEquals("Skip 3 (EOF)", -1, input.skip(5)); // End of file
        try {
            input.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 NullInputStream implementation -------------

    private static final class TestNullInputStream extends NullInputStream {
        public TestNullInputStream(int size) {
            super(size);
        }
        public TestNullInputStream(int size, boolean markSupported, boolean throwEofException) {
            super(size, markSupported, throwEofException);
        }
        @Override
        protected int processByte() {
            return ((int)getPosition() - 1);
        }
        @Override
        protected void processBytes(byte[] bytes, int offset, int length) {
            int startPos = (int)getPosition() - length;
            for (int i = offset; i < length; i++) {
                bytes[i] = (byte)(startPos + i);
            }
        }
        
    }
}