diff --git a/core-java-io/src/test/java/com/baeldung/file/FilesClearDataUnitTest.java b/core-java-io/src/test/java/com/baeldung/file/FilesClearDataUnitTest.java new file mode 100644 index 0000000000..8302124f32 --- /dev/null +++ b/core-java-io/src/test/java/com/baeldung/file/FilesClearDataUnitTest.java @@ -0,0 +1,96 @@ +package com.baeldung.file; + +import static org.junit.jupiter.api.Assertions.assertEquals; + +import java.io.BufferedWriter; +import java.io.File; +import java.io.FileInputStream; +import java.io.FileOutputStream; +import java.io.FileWriter; +import java.io.IOException; +import java.io.PrintWriter; +import java.nio.channels.FileChannel; +import java.nio.charset.Charset; +import java.nio.file.Files; +import java.nio.file.Paths; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.FileUtils; +import org.junit.After; +import org.junit.Before; +import org.junit.Test; + +import com.baeldung.util.StreamUtils; + +public class FilesClearDataUnitTest { + + public static final String FILE_PATH = "src/test/resources/fileexample.txt"; + + @Before + @After + public void setup() throws IOException { + PrintWriter writer = new PrintWriter(FILE_PATH); + writer.print("This example shows how we can delete the file contents without deleting the file"); + writer.close(); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingPrintWritter_thenEmptyFile() throws IOException { + PrintWriter writer = new PrintWriter(FILE_PATH); + writer.print(""); + writer.close(); + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingPrintWritterWithougObject_thenEmptyFile() throws IOException { + new PrintWriter(FILE_PATH).close(); + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingFileWriter_thenEmptyFile() throws IOException { + new FileWriter(FILE_PATH, false).close(); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingFileOutputStream_thenEmptyFile() throws IOException { + new FileOutputStream(FILE_PATH).close(); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingFileUtils_thenEmptyFile() throws IOException { + FileUtils.write(new File(FILE_PATH), "", Charset.defaultCharset()); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingNIOFiles_thenEmptyFile() throws IOException { + BufferedWriter writer = Files.newBufferedWriter(Paths.get(FILE_PATH)); + writer.write(""); + writer.flush(); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingNIOFileChannel_thenEmptyFile() throws IOException { + FileChannel.open(Paths.get(FILE_PATH), StandardOpenOption.WRITE).truncate(0).close(); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } + + @Test + public void givenExistingFile_whenDeleteContentUsingGuava_thenEmptyFile() throws IOException { + File file = new File(FILE_PATH); + byte[] empty = new byte[0]; + com.google.common.io.Files.write(empty, file); + + assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length()); + } +} diff --git a/core-java-io/src/test/resources/fileexample.txt b/core-java-io/src/test/resources/fileexample.txt new file mode 100644 index 0000000000..ee48fdfb84 --- /dev/null +++ b/core-java-io/src/test/resources/fileexample.txt @@ -0,0 +1 @@ +This example shows how we can delete the file contents without deleting the file \ No newline at end of file