ZipTest.java

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import static org.junit.Assert.assertFalse;

public class ZipTest {

    public static final String ZIP_FILE = "file.zip";
    public static final String FILE = "file.txt";

    @Rule
    public TemporaryFolder tmp = new TemporaryFolder();

    private File root;
    private File dir;
    private File file;

    @Before
    public void setUp() throws Exception {
        root = tmp.getRoot();
        dir = tmp.newFolder();
        file = createZipFile(dir);
    }

    @Test
    public void shouldFailIfRootCreatedInRootDir() throws Exception {
        try {
            YourZipLibrary.extractZip(file, dir); // todo
        } catch (Exception ignored) { }
        assertFalse(new File(root, FILE).exists());
    }

    public File createZipFile(File dir) throws IOException {
        final File file = new File(dir, ZIP_FILE);
        try (final ZipOutputStream output = new ZipOutputStream(new FileOutputStream(file))) {
            output.putNextEntry(new ZipEntry("../" + FILE));
            final byte[] bytes = "Hello world".getBytes();
            output.write(bytes, 0, bytes.length);
            return file;
        }
    }
}