glytching / junit-extensions

 * 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 io.github.glytching.junit.extension.folder;

import org.junit.jupiter.api.extension.ExtensionContext.Store.CloseableResource;

import java.io.File;

import java.io.IOException;

import java.nio.file.*;

import java.nio.file.attribute.BasicFileAttributes;

import static java.nio.file.FileVisitResult.CONTINUE;

/**

 * Encapsulates the {@link #rootFolder} within which any files or directories will be created along

 * with the operations which a tester may wish to invoke ({@link #createFile(String)}, {@link

 * #createDirectory(String)}) and post test invocations which the associated extension will invoke.

 */

@SuppressWarnings({"ResultOfMethodCallIgnored", "nls"})

public class TemporaryFolder implements CloseableResource {

  private static final String FILE_PREFIX = "junit";

  private static final String FILE_SUFFIX = ".tmp";

  /**

   * The root folder within which any files or directories will be created, on {@link #destroy()}

   * this folder and all of its contents will be silently deleted.

   */

  private final File rootFolder;

  /**

   * Package protected since a {@link TemporaryFolder}'s lifecycle is expected to be controlled by

   * its associated extension.

   */

  TemporaryFolder() {

    try {

      rootFolder = File.createTempFile(FILE_PREFIX, FILE_SUFFIX);

      Files.delete(rootFolder.toPath());

      Files.createDirectory(rootFolder.toPath());

    } catch (IOException ex) {

      throw new TemporaryFolderException("Failed to prepare root folder!", ex);

    }

  }

  @Override

  public void close() throws Throwable {

    destroy();

  }

  /**

   * Returns the root folder. Exposing this offers some back compatability with JUnit4's {@code

   * TemporaryFolder} so test cases which are used to invoking {@code getRoot()} on a JUnit4 rule

   * can adopt the same approach with this {@code TemporaryFolder}. In addition, this may be useful

   * where you want to use the root folder itself without creating files or directories within it.

   *

   * <p><b>Note:</b> the extension is responsible for creating/managing/destroying the root folder

   * so don't bother trying to clean it up yourself and don't expect that anything you do to it will

   * survive post-test-cleanup.

   *

   * @see <a href="https://github.com/glytching/junit-extensions/issues/8">Issue 8</a>

   * @return the root folder

   */

  public File getRoot() {

    return rootFolder;

  }

  /**

   * Create a file within the temporary folder root.

   *

   * @param fileName the name of the file to be created

   * @return the newly created file instance

   * @throws IOException in case the file creation call fails

   */

  public File createFile(String fileName) throws IOException {

    Path path = Paths.get(rootFolder.getPath(), fileName);

    return Files.createFile(path).toFile();

  }

  /**

   * Create a directory within the temporary folder root.

   *

   * @param directoryName the name of the directory to be created

   * @return the directory instance

   */

  }

  /**

   * Deletes the {@link #rootFolder} and all of its contents. This is package protected because a

   * {@link TemporaryFolder}'s lifecycle is expected to be controlled by its associated extension.

   *

   * <p><b>Note</b>: any exception encountered during deletion will be swallowed.

   */

  void destroy() throws IOException {

    if (rootFolder.exists()) {

      // walk the contents deleting each

      Files.walkFileTree(

          rootFolder.toPath(),

          new SimpleFileVisitor<Path>() {

            @Override

            public FileVisitResult visitFile(Path file, BasicFileAttributes attributes)

                throws IOException {

              return delete(file);

            }

            @Override

            public FileVisitResult postVisitDirectory(Path directory, IOException exception)

                throws IOException {

              return delete(directory);

            }

            @SuppressWarnings("SameReturnValue")

            private FileVisitResult delete(Path file) throws IOException {

              Files.delete(file);

              return CONTINUE;

            }

          });

      if (rootFolder.exists()) {

        // delete the parent, if it still exists

        Files.delete(rootFolder.toPath());

      }

    }

  }

}