src/test/java/org/apache/maven/shared/utils/testhelpers/FileTestHelper.java

/*
 * 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.maven.shared.utils.testhelpers;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.apache.commons.io.FileUtils;
import org.junit.rules.TemporaryFolder;

/**
 * A few utility methods for file based tests.
 */
public final class FileTestHelper {

    private FileTestHelper() {
        // utility function doesn't need a public constructor
    }

    public static void generateTestData(OutputStream out, long size) throws IOException {
        for (int i = 0; i < size; i++) {
            // nice varied byte pattern compatible with Readers and Writers
            out.write((byte) ((i % 127) + 1));
        }
    }

    public static void generateTestFile(File testfile, int size) throws IOException {
        if (testfile.exists()) {
            //noinspection ResultOfMethodCallIgnored
            testfile.delete();
        }

        try (OutputStream os = new FileOutputStream(testfile)) {
            generateTestData(os, size);
            os.flush();
        }
    }

    public static 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");
        }

        try (Writer out = new OutputStreamWriter(new FileOutputStream(file), "UTF-8")) {
            for (String aData : data) {
                out.write(aData);
                out.write(System.lineSeparator());
            }
        }
    }

    /**
     * Check if the given file exists in the given folder and remove it.
     *
     * @return the File object for a new file
     * @throws IOException
     */
    public static File newFile(TemporaryFolder folder, String filename) throws IOException {
        File destination = folder.newFile(filename);

        if (destination.exists()) {
            FileUtils.deleteQuietly(destination);
        }
        return destination;
    }
}