BAEL-1075 (#2497)

* Adding test cases for "how to delete a directory"

* Removing .gitignore from Empty folder

* Adding .gitignore to Empty folder

* Updated method names and removed unnecessary imports

* Removed toBedeleted folder from src/test/resources. Updated the test
case to create the directory on the fly using a temporary location

core-java/pom.xml

@@ -162,6 +162,12 @@
             <version>${avaitility.version}</version>
             <scope>test</scope>
         </dependency>
+		<dependency>
+		    <groupId>org.springframework</groupId>
+		    <artifactId>spring-core</artifactId>
+		    <version>${spring-core.version}</version>
+		    <scope>test</scope>
+		</dependency>
 
         <dependency>
             <groupId>commons-codec</groupId>
@@ -439,6 +445,7 @@
         <mockito.version>2.8.9</mockito.version>
         <assertj.version>3.6.1</assertj.version>
         <avaitility.version>1.7.0</avaitility.version>
+        <spring-core.version>4.3.10.RELEASE</spring-core.version>
 
 
         <!-- maven plugins -->

core-java/src/test/java/org/baeldung/java/io/JavaDirectoryDeleteUnitTest.java

@@ -0,0 +1,143 @@
+package org.baeldung.java.io;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.springframework.util.FileSystemUtils;
+
+public class JavaDirectoryDeleteUnitTest {
+    private static Path TEMP_DIRECTORY;
+    private static final String DIRECTORY_NAME = "toBeDeleted";
+
+    public static final List<String> ALL_LINES = Arrays.asList(new String[] { "This is line 1", "This is line 2", "This is line 3", "This is line 4", "This is line 5", "This is line 6" });
+
+    @BeforeClass
+    public static void initializeTempDirectory() throws IOException {
+        TEMP_DIRECTORY = Files.createTempDirectory("tmpForJUnit");
+    }
+
+    @AfterClass
+    public static void cleanTempDirectory() throws IOException {
+        FileUtils.deleteDirectory(TEMP_DIRECTORY.toFile());
+    }
+
+    @Before
+    public void setupDirectory() throws IOException {
+        Path tempPathForEachTest = Files.createDirectory(TEMP_DIRECTORY.resolve(DIRECTORY_NAME));
+
+        // Create a directory structure
+        Files.write(tempPathForEachTest.resolve("file1.txt"), ALL_LINES.subList(0, 2));
+        Files.write(tempPathForEachTest.resolve("file2.txt"), ALL_LINES.subList(2, 4));
+
+        Files.createDirectories(tempPathForEachTest.resolve("Empty"));
+
+        Path aSubDir = Files.createDirectories(tempPathForEachTest.resolve("notEmpty"));
+        Files.write(aSubDir.resolve("file3.txt"), ALL_LINES.subList(3, 5));
+        Files.write(aSubDir.resolve("file4.txt"), ALL_LINES.subList(0, 3));
+
+        aSubDir = Files.createDirectories(aSubDir.resolve("anotherSubDirectory"));
+        Files.write(aSubDir.resolve("file5.txt"), ALL_LINES.subList(4, 5));
+        Files.write(aSubDir.resolve("file6.txt"), ALL_LINES.subList(0, 2));
+    }
+
+    @After
+    public void checkAndCleanupIfRequired() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+        if (Files.exists(pathToBeDeleted)) {
+            FileUtils.deleteDirectory(pathToBeDeleted.toFile());
+        }
+    }
+
+    boolean deleteDirectory(File directoryToBeDeleted) {
+        File[] allContents = directoryToBeDeleted.listFiles();
+
+        for (File file : allContents) {
+            if (file.isDirectory()) {
+                deleteDirectory(file);
+            } else {
+                file.delete();
+            }
+        }
+
+        return directoryToBeDeleted.delete();
+    }
+
+    @Test
+    public void givenDirectory_whenDeletedWithRecursion_thenIsGone() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+
+        boolean result = deleteDirectory(pathToBeDeleted.toFile());
+
+        assertTrue("Could not delete directory", result);
+        assertFalse("Directory still exists", Files.exists(pathToBeDeleted));
+    }
+
+    @Test
+    public void givenDirectory_whenDeletedWithCommonsIOFileUtils_thenIsGone() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+
+        FileUtils.deleteDirectory(pathToBeDeleted.toFile());
+
+        assertFalse("Directory still exists", Files.exists(pathToBeDeleted));
+    }
+
+    @Test
+    public void givenDirectory_whenDeletedWithSpringFileSystemUtils_thenIsGone() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+
+        boolean result = FileSystemUtils.deleteRecursively(pathToBeDeleted.toFile());
+
+        assertTrue("Could not delete directory", result);
+        assertFalse("Directory still exists", Files.exists(pathToBeDeleted));
+    }
+
+    @Test
+    public void givenDirectory_whenDeletedWithFilesWalk_thenIsGone() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+
+        Files.walk(pathToBeDeleted)
+            .sorted(Comparator.reverseOrder())
+            .map(Path::toFile)
+            .forEach(File::delete);
+
+        assertFalse("Directory still exists", Files.exists(pathToBeDeleted));
+    }
+
+    @Test
+    public void givenDirectory_whenDeletedWithNIO2WalkFileTree_thenIsGone() throws IOException {
+        Path pathToBeDeleted = TEMP_DIRECTORY.resolve(DIRECTORY_NAME);
+
+        Files.walkFileTree(pathToBeDeleted, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+                Files.delete(dir);
+                return FileVisitResult.CONTINUE;
+            }
+
+            @Override
+            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+                Files.delete(file);
+                return FileVisitResult.CONTINUE;
+            }
+        });
+
+        assertFalse("Directory still exists", Files.exists(pathToBeDeleted));
+    }
+}