With the method writeString
introduced in Java 11, writing a String to a file takes a single line:
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import org.junit.jupiter.api.Test;
//...
@Test
public void writeString() throws IOException {
Path fileName = Path.of("celebration.txt");
String content = "duke is 25";
Files.writeString(fileName, content);
String actual = Files.readString(fileName);
assertEquals(content,actual);
}