package org.junit.rules;

import java.io.File;
import java.io.IOException;

import org.junit.Rule;

The TemporaryFolder Rule allows creation of files and folders that should
be deleted when the test method finishes (whether it passes or
fails). Whether the deletion is successful or not is not checked by this rule.
No exception will be thrown in case the deletion fails.
Example of usage:
public static class HasTempFolder {
 @Rule
 public TemporaryFolder folder= new TemporaryFolder();
 @Test
 public void testUsingTempFolder() throws IOException {
     File createdFile= folder.newFile("myfile.txt");
     File createdFolder= folder.newFolder("subfolder");
     // ...
    }
}

Since:
4.7/**
 * The TemporaryFolder Rule allows creation of files and folders that should
 * be deleted when the test method finishes (whether it passes or
 * fails). Whether the deletion is successful or not is not checked by this rule.
 * No exception will be thrown in case the deletion fails.
 *
 * <p>Example of usage:
 * <pre>
 * public static class HasTempFolder {
 *  &#064;Rule
 *  public TemporaryFolder folder= new TemporaryFolder();
 *
 *  &#064;Test
 *  public void testUsingTempFolder() throws IOException {
 *      File createdFile= folder.newFile(&quot;myfile.txt&quot;);
 *      File createdFolder= folder.newFolder(&quot;subfolder&quot;);
 *      // ...
 *     }
 * }
 * </pre>
 *
 * @since 4.7
 */
public class TemporaryFolder extends ExternalResource {
    private final File parentFolder;
    private File folder;

    public TemporaryFolder() {
        this(null);
    }

    public TemporaryFolder(File parentFolder) {
        this.parentFolder = parentFolder;
    }

    @Override
    protected void before() throws Throwable {
        create();
    }

    @Override
    protected void after() {
        delete();
    }

    // testing purposes only

    
for testing purposes only. Do not use.
/**
     * for testing purposes only. Do not use.
     */
    public void create() throws IOException {
        folder = createTemporaryFolderIn(parentFolder);
    }

    
Returns a new fresh file with the given name under the temporary folder.
/**
     * Returns a new fresh file with the given name under the temporary folder.
     */
    public File newFile(String fileName) throws IOException {
        File file = new File(getRoot(), fileName);
        if (!file.createNewFile()) {
            throw new IOException(
                    "a file with the name \'" + fileName + "\' already exists in the test folder");
        }
        return file;
    }

    
Returns a new fresh file with a random name under the temporary folder.
/**
     * Returns a new fresh file with a random name under the temporary folder.
     */
    public File newFile() throws IOException {
        return File.createTempFile("junit", null, getRoot());
    }

    
Returns a new fresh folder with the given name under the temporary
folder.
/**
     * Returns a new fresh folder with the given name under the temporary
     * folder.
     */
    public File newFolder(String folder) throws IOException {
        return newFolder(new String[]{folder});
    }

    
Returns a new fresh folder with the given name(s) under the temporary
folder.
/**
     * Returns a new fresh folder with the given name(s) under the temporary
     * folder.
     */
    public File newFolder(String... folderNames) throws IOException {
        File file = getRoot();
        for (int i = 0; i < folderNames.length; i++) {
            String folderName = folderNames[i];
            validateFolderName(folderName);
            file = new File(file, folderName);
            if (!file.mkdir() && isLastElementInArray(i, folderNames)) {
                throw new IOException(
                        "a folder with the name \'" + folderName + "\' already exists");
            }
        }
        return file;
    }
    
    
Validates if multiple path components were used while creating a folder.
Params:
folderName – 
           Name of the folder being created/**
     * Validates if multiple path components were used while creating a folder.
     * 
     * @param folderName
     *            Name of the folder being created
     */
    private void validateFolderName(String folderName) throws IOException {
        File tempFile = new File(folderName);
        if (tempFile.getParent() != null) {
            String errorMsg = "Folder name cannot consist of multiple path components separated by a file separator."
                    + " Please use newFolder('MyParentFolder','MyFolder') to create hierarchies of folders";
            throw new IOException(errorMsg);
        }
    }

    private boolean isLastElementInArray(int index, String[] array) {
        return index == array.length - 1;
    }

    
Returns a new fresh folder with a random name under the temporary folder.
/**
     * Returns a new fresh folder with a random name under the temporary folder.
     */
    public File newFolder() throws IOException {
        return createTemporaryFolderIn(getRoot());
    }

    private File createTemporaryFolderIn(File parentFolder) throws IOException {
        File createdFolder = File.createTempFile("junit", "", parentFolder);
        createdFolder.delete();
        createdFolder.mkdir();
        return createdFolder;
    }

    
Returns:
the location of this temporary folder./**
     * @return the location of this temporary folder.
     */
    public File getRoot() {
        if (folder == null) {
            throw new IllegalStateException(
                    "the temporary folder has not yet been created");
        }
        return folder;
    }

    
Delete all files and folders under the temporary folder. Usually not called directly, since it is automatically applied by the Rule /**
     * Delete all files and folders under the temporary folder. Usually not
     * called directly, since it is automatically applied by the {@link Rule}
     */
    public void delete() {
        if (folder != null) {
            recursiveDelete(folder);
        }
    }

    private void recursiveDelete(File file) {
        File[] files = file.listFiles();
        if (files != null) {
            for (File each : files) {
                recursiveDelete(each);
            }
        }
        file.delete();
    }
}