Commons IO example source code file (FileBasedTestCase.java)

This example Commons IO source code file (FileBasedTestCase.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

bufferedoutputstream, bytearrayoutputstream, cannot, different, exception, exception, file, file, inputstream, io, ioexception, ioexception, printwriter, the, the, util

The Commons IO FileBasedTestCase.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.testtools;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
import java.util.Arrays;

import junit.framework.AssertionFailedError;
import junit.framework.TestCase;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.output.ByteArrayOutputStream;

/**
 * Base class for testcases doing tests with files.
 * 
 * @author Jeremias Maerki
 * @author Gareth Davis
 */
public abstract class FileBasedTestCase extends TestCase {

    private static volatile File testDir;

    public FileBasedTestCase(String name) {
        super(name);
    }
    
    public static File getTestDirectory() {
        if (testDir == null) {
            testDir = (new File("test/io/")).getAbsoluteFile();
        }
        testDir.mkdirs();
        return testDir;
    }
    
    protected void createFile(File file, long size)
            throws IOException {
        if (!file.getParentFile().exists()) {
            throw new IOException("Cannot create file " + file 
                + " as the parent directory does not exist");
        }
        BufferedOutputStream output =
            new BufferedOutputStream(new java.io.FileOutputStream(file));
        try {
            generateTestData(output, size);
        } finally {
            IOUtils.closeQuietly(output);
        }
    }
    
    protected byte[] generateTestData(long size) {
        try {
            ByteArrayOutputStream baout = new ByteArrayOutputStream();
            generateTestData(baout, size);
            return baout.toByteArray();
        } catch (IOException ioe) {
            throw new RuntimeException("This should never happen: " + ioe.getMessage());
        }
    }
    
    protected void generateTestData(OutputStream out, long size) 
                throws IOException {
        for (int i = 0; i < size; i++) {
            //output.write((byte)'X');

            // nice varied byte pattern compatible with Readers and Writers
            out.write( (byte)( (i % 127) + 1) );
        }
    }

    protected void createLineBasedFile(File file, String[] data) throws IOException {
        if (file.getParentFile() != null && !file.getParentFile().exists()) {
            throw new IOException("Cannot create file " + file + " as the parent directory does not exist");
        }
        PrintWriter output = new PrintWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF-8"));
        try {
            for (int i = 0; i < data.length; i++) {
                output.println(data[i]);
            }
        } finally {
            IOUtils.closeQuietly(output);
        }
    }

    protected File newFile(String filename) throws IOException {
        File destination = new File( getTestDirectory(), filename );
        /*
        assertTrue( filename + "Test output data file shouldn't previously exist",
                    !destination.exists() );
        */
        if (destination.exists()) {
            FileUtils.forceDelete(destination);
        }
        return destination;
    }

    protected void checkFile( File file, File referenceFile )
                throws Exception {
        assertTrue( "Check existence of output file", file.exists() );
        assertEqualContent( referenceFile, file );
    }

    /** Assert that the content of two files is the same. */
    private void assertEqualContent( File f0, File f1 )
        throws IOException
    {
        /* This doesn't work because the filesize isn't updated until the file
         * is closed.
        assertTrue( "The files " + f0 + " and " + f1 +
                    " have differing file sizes (" + f0.length() +
                    " vs " + f1.length() + ")", ( f0.length() == f1.length() ) );
        */
        InputStream is0 = new java.io.FileInputStream( f0 );
        try {
            InputStream is1 = new java.io.FileInputStream( f1 );
            try {
                byte[] buf0 = new byte[ 1024 ];
                byte[] buf1 = new byte[ 1024 ];
                int n0 = 0;
                int n1 = 0;

                while( -1 != n0 )
                {
                    n0 = is0.read( buf0 );
                    n1 = is1.read( buf1 );
                    assertTrue( "The files " + f0 + " and " + f1 +
                                " have differing number of bytes available (" + n0 +
                                " vs " + n1 + ")", ( n0 == n1 ) );

                    assertTrue( "The files " + f0 + " and " + f1 +
                                " have different content", Arrays.equals( buf0, buf1 ) );
                }
            } finally {
                is1.close();
            }
        } finally {
            is0.close();
        }
    }

    /** Assert that the content of a file is equal to that in a byte[]. */
    protected void assertEqualContent(byte[] b0, File file) throws IOException {
        InputStream is = new java.io.FileInputStream(file);
        int count = 0, numRead = 0;
        byte[] b1 = new byte[b0.length];
        try {
            while (count < b0.length && numRead >= 0) {
                numRead = is.read(b1, count, b0.length);
                count += numRead;
            }
            assertEquals("Different number of bytes: ", b0.length, count);
            for (int i = 0; i < count; i++) {
                assertEquals("byte " + i + " differs", b0[i], b1[i]);
            }
        } finally {
            is.close();
        }
    }

    /** Assert that the content of a file is equal to that in a char[]. */
    protected void assertEqualContent(char[] c0, File file) throws IOException {
        Reader ir = new java.io.FileReader(file);
        int count = 0, numRead = 0;
        char[] c1 = new char[c0.length];
        try {
            while (count < c0.length && numRead >= 0) {
                numRead = ir.read(c1, count, c0.length);
                count += numRead;
            }
            assertEquals("Different number of chars: ", c0.length, count);
            for (int i = 0; i < count; i++) {
                assertEquals("char " + i + " differs", c0[i], c1[i]);
            }
        } finally {
            ir.close();
        }
    }

    protected void checkWrite(OutputStream output) throws Exception {
        try {
            new java.io.PrintStream(output).write(0);
        } catch (Throwable t) {
            throw new AssertionFailedError(
                "The copy() method closed the stream "
                    + "when it shouldn't have. "
                    + t.getMessage());
        }
    }

    protected void checkWrite(Writer output) throws Exception {
        try {
            new java.io.PrintWriter(output).write('a');
        } catch (Throwable t) {
            throw new AssertionFailedError(
                "The copy() method closed the stream "
                    + "when it shouldn't have. "
                    + t.getMessage());
        }
    }

    protected void deleteFile( File file )
        throws Exception {
        if (file.exists()) {
            assertTrue("Couldn't delete file: " + file, file.delete());
        }
    }
    

}