UtilTest.java

/*
 * The MIT License
 *
 * Copyright (c) 2004-2010, Sun Microsystems, Inc., Kohsuke Kawaguchi,
 * Daniel Dyer, Erik Ramfelt, Richard Bair, id:cactusman
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package hudson;

import hudson.model.TaskListener;
import hudson.os.WindowsUtil;
import hudson.util.StreamTaskListener;
import org.apache.commons.io.FileUtils;
import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.junit.Assume;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import org.junit.rules.TemporaryFolder;
import org.jvnet.hudson.test.Issue;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.PosixFilePermissions;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

import static org.hamcrest.CoreMatchers.not;
import static org.hamcrest.CoreMatchers.startsWith;
import static org.junit.Assert.*;

/**
 * @author Kohsuke Kawaguchi
 */
public class UtilTest {

    @Rule public TemporaryFolder tmp = new TemporaryFolder();

    @Rule public ExpectedException expectedException = ExpectedException.none();

    @Test
    public void testReplaceMacro() {
        Map<String,String> m = new HashMap<String,String>();
        m.put("A","a");
        m.put("A.B","a-b");
        m.put("AA","aa");
        m.put("B","B");
        m.put("DOLLAR", "$");
        m.put("ENCLOSED", "a${A}");

        // longest match
        assertEquals("aa",Util.replaceMacro("$AA",m));

        // invalid keys are ignored
        assertEquals("$AAB",Util.replaceMacro("$AAB",m));

        assertEquals("aaB",Util.replaceMacro("${AA}B",m));
        assertEquals("${AAB}",Util.replaceMacro("${AAB}",m));

        // $ escaping
        assertEquals("asd$${AA}dd", Util.replaceMacro("asd$$$${AA}dd",m));
        assertEquals("$", Util.replaceMacro("$$",m));
        assertEquals("$$", Util.replaceMacro("$$$$",m));

        // dots
        assertEquals("a.B", Util.replaceMacro("$A.B", m));
        assertEquals("a-b", Util.replaceMacro("${A.B}", m));

    	// test that more complex scenarios work
        assertEquals("/a/B/aa", Util.replaceMacro("/$A/$B/$AA",m));
        assertEquals("a-aa", Util.replaceMacro("$A-$AA",m));
        assertEquals("/a/foo/can/B/you-believe_aa~it?", Util.replaceMacro("/$A/foo/can/$B/you-believe_$AA~it?",m));
        assertEquals("$$aa$Ba${A}$it", Util.replaceMacro("$$$DOLLAR${AA}$$B${ENCLOSED}$it",m));
    }

    @Test
    public void testTimeSpanString() {
        // Check that amounts less than 365 days are not rounded up to a whole year.
        // In the previous implementation there were 360 days in a year.
        // We're still working on the assumption that a month is 30 days, so there will
        // be 5 days at the end of the year that will be "12 months" but not "1 year".
        // First check 359 days.
        assertEquals(Messages.Util_month(11), Util.getTimeSpanString(31017600000L));
        // And 362 days.
        assertEquals(Messages.Util_month(12), Util.getTimeSpanString(31276800000L));

        // 11.25 years - Check that if the first unit has 2 or more digits, a second unit isn't used.
        assertEquals(Messages.Util_year(11), Util.getTimeSpanString(354780000000L));
        // 9.25 years - Check that if the first unit has only 1 digit, a second unit is used.
        assertEquals(Messages.Util_year(9)+ " " + Messages.Util_month(3), Util.getTimeSpanString(291708000000L));
        // 67 seconds
        assertEquals(Messages.Util_minute(1) + " " + Messages.Util_second(7), Util.getTimeSpanString(67000L));
        // 17 seconds - Check that times less than a minute only use seconds.
        assertEquals(Messages.Util_second(17), Util.getTimeSpanString(17000L));
        // 1712ms -> 1.7sec
        assertEquals(Messages.Util_second(1.7), Util.getTimeSpanString(1712L));
        // 171ms -> 0.17sec
        assertEquals(Messages.Util_second(0.17), Util.getTimeSpanString(171L));
        // 101ms -> 0.10sec
        assertEquals(Messages.Util_second(0.1), Util.getTimeSpanString(101L));
        // 17ms
        assertEquals(Messages.Util_millisecond(17), Util.getTimeSpanString(17L));
        // 1ms
        assertEquals(Messages.Util_millisecond(1), Util.getTimeSpanString(1L));
        // Test HUDSON-2843 (locale with comma as fraction separator got exception for <10 sec)
        Locale saveLocale = Locale.getDefault();
        Locale.setDefault(Locale.GERMANY);
        try {
            // Just verifying no exception is thrown:
            assertNotNull("German locale", Util.getTimeSpanString(1234));
            assertNotNull("German locale <1 sec", Util.getTimeSpanString(123));
        }
        finally { Locale.setDefault(saveLocale); }
    }


    /**
     * Test that Strings that contain spaces are correctly URL encoded.
     */
    @Test
    public void testEncodeSpaces() {
        final String urlWithSpaces = "http://hudson/job/Hudson Job";
        String encoded = Util.encode(urlWithSpaces);
        assertEquals(encoded, "http://hudson/job/Hudson%20Job");
    }

    /**
     * Test the rawEncode() method.
     */
    @Test
    public void testRawEncode() {
        String[] data = {  // Alternating raw,encoded
            "abcdefghijklmnopqrstuvwxyz", "abcdefghijklmnopqrstuvwxyz",
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
            "01234567890!@$&*()-_=+',.", "01234567890!@$&*()-_=+',.",
            " \"#%/:;<>?", "%20%22%23%25%2F%3A%3B%3C%3E%3F",
            "[\\]^`{|}~", "%5B%5C%5D%5E%60%7B%7C%7D%7E",
            "d\u00E9velopp\u00E9s", "d%C3%A9velopp%C3%A9s",
            "Foo \uD800\uDF98 Foo", "Foo%20%F0%90%8E%98%20Foo"
        };
        for (int i = 0; i < data.length; i += 2) {
            assertEquals("test " + i, data[i + 1], Util.rawEncode(data[i]));
        }
    }

    /**
     * Test the tryParseNumber() method.
     */
    @Test
    public void testTryParseNumber() {
        assertEquals("Successful parse did not return the parsed value", 20, Util.tryParseNumber("20", 10).intValue());
        assertEquals("Failed parse did not return the default value", 10, Util.tryParseNumber("ss", 10).intValue());
        assertEquals("Parsing empty string did not return the default value", 10, Util.tryParseNumber("", 10).intValue());
        assertEquals("Parsing null string did not return the default value", 10, Util.tryParseNumber(null, 10).intValue());
    }

    @Test
    public void testSymlink() throws Exception {
        Assume.assumeFalse(Functions.isWindows());

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        StreamTaskListener l = new StreamTaskListener(baos);
        File d = tmp.getRoot();
        try {
            new FilePath(new File(d, "a")).touch(0);
            assertNull(Util.resolveSymlink(new File(d, "a")));
            Util.createSymlink(d,"a","x", l);
            assertEquals("a",Util.resolveSymlink(new File(d,"x")));

            // test a long name
            StringBuilder buf = new StringBuilder(768);
            for( int i=0; i<768; i++)
                buf.append((char)('0'+(i%10)));
            Util.createSymlink(d,buf.toString(),"x", l);

            String log = baos.toString();
            if (log.length() > 0)
                System.err.println("log output: " + log);

            assertEquals(buf.toString(),Util.resolveSymlink(new File(d,"x")));


            // test linking from another directory
            File anotherDir = new File(d,"anotherDir");
            assertTrue("Couldn't create "+anotherDir,anotherDir.mkdir());

            Util.createSymlink(d,"a","anotherDir/link",l);
            assertEquals("a",Util.resolveSymlink(new File(d,"anotherDir/link")));

            // JENKINS-12331: either a bug in createSymlink or this isn't supposed to work:
            //assertTrue(Util.isSymlink(new File(d,"anotherDir/link")));

            File external = File.createTempFile("something", "");
            try {
                Util.createSymlink(d, external.getAbsolutePath(), "outside", l);
                assertEquals(external.getAbsolutePath(), Util.resolveSymlink(new File(d, "outside")));
            } finally {
                assertTrue(external.delete());
            }
        } finally {
            Util.deleteRecursive(d);
        }
    }

    @Test
    public void testIsSymlink() throws IOException, InterruptedException {
        Assume.assumeFalse(Functions.isWindows());

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        StreamTaskListener l = new StreamTaskListener(baos);
        File d = tmp.getRoot();
        try {
            new FilePath(new File(d, "original")).touch(0);
            assertFalse(Util.isSymlink(new File(d, "original")));
            Util.createSymlink(d,"original","link", l);

            assertTrue(Util.isSymlink(new File(d, "link")));

            // test linking to another directory
            File dir = new File(d,"dir");
            assertTrue("Couldn't create "+dir,dir.mkdir());
            assertFalse(Util.isSymlink(new File(d,"dir")));

            File anotherDir = new File(d,"anotherDir");
            assertTrue("Couldn't create "+anotherDir,anotherDir.mkdir());

            Util.createSymlink(d,"dir","anotherDir/symlinkDir",l);
            // JENKINS-12331: either a bug in createSymlink or this isn't supposed to work:
            // assertTrue(Util.isSymlink(new File(d,"anotherDir/symlinkDir")));
        } finally {
            Util.deleteRecursive(d);
        }
    }

    @Test
    public void testIsSymlink_onWindows_junction() throws Exception {
        Assume.assumeTrue("Uses Windows-specific features", Functions.isWindows());
        File targetDir = tmp.newFolder("targetDir");
        File d = tmp.newFolder("dir");
        File junction = WindowsUtil.createJunction(new File(d, "junction"), targetDir);
        assertTrue(Util.isSymlink(junction));
    }

    @Test
    @Issue("JENKINS-55448")
    public void testIsSymlink_ParentIsJunction() throws IOException, InterruptedException {
        Assume.assumeTrue("Uses Windows-specific features", Functions.isWindows());
        File targetDir = tmp.newFolder();
        File file = new File(targetDir, "test-file");
        new FilePath(file).touch(System.currentTimeMillis());
        File dir = tmp.newFolder();
        File junction = WindowsUtil.createJunction(new File(dir, "junction"), targetDir);

        assertTrue(Util.isSymlink(junction));
        assertFalse(Util.isSymlink(file));
    }

    @Test
    @Issue("JENKINS-55448")
    public void testIsSymlink_ParentIsSymlink() throws IOException, InterruptedException {
        File folder = tmp.newFolder();
        File file = new File(folder, "test-file");
        new FilePath(file).touch(System.currentTimeMillis());
        Path link = tmp.getRoot().toPath().resolve("sym-link");
        Path pathWithSymlinkParent = Files.createSymbolicLink(link, folder.toPath()).resolve("test-file");
        assertTrue(Util.isSymlink(link));
        assertFalse(Util.isSymlink(pathWithSymlinkParent));
    }

    @Test
    public void testHtmlEscape() {
        assertEquals("<br>", Util.escape("\n"));
        assertEquals("&lt;a&gt;", Util.escape("<a>"));
        assertEquals("&#039;&quot;", Util.escape("'\""));
        assertEquals("&nbsp; ", Util.escape("  "));
    }

    /**
     * Compute 'known-correct' digests and see if I still get them when computed concurrently
     * to another digest.
     */
    @Issue("JENKINS-10346")
    @Test
    public void testDigestThreadSafety() throws InterruptedException {
    	String a = "abcdefgh";
    	String b = "123456789";

    	String digestA = Util.getDigestOf(a);
    	String digestB = Util.getDigestOf(b);

    	DigesterThread t1 = new DigesterThread(a, digestA);
    	DigesterThread t2 = new DigesterThread(b, digestB);

    	t1.start();
    	t2.start();

    	t1.join();
    	t2.join();

    	if (t1.error != null) {
    		fail(t1.error);
    	}
    	if (t2.error != null) {
    		fail(t2.error);
    	}
    }

    private static class DigesterThread extends Thread {
    	private String string;
		private String expectedDigest;

		private String error;

		public DigesterThread(String string, String expectedDigest) {
    		this.string = string;
    		this.expectedDigest = expectedDigest;
    	}

		public void run() {
			for (int i=0; i < 1000; i++) {
				String digest = Util.getDigestOf(this.string);
				if (!this.expectedDigest.equals(digest)) {
					this.error = "Expected " + this.expectedDigest + ", but got " + digest;
					break;
				}
			}
		}
    }

    @Test
    public void testIsAbsoluteUri() {
        assertTrue(Util.isAbsoluteUri("http://foobar/"));
        assertTrue(Util.isAbsoluteUri("mailto:kk@kohsuke.org"));
        assertTrue(Util.isAbsoluteUri("d123://test/"));
        assertFalse(Util.isAbsoluteUri("foo/bar/abc:def"));
        assertFalse(Util.isAbsoluteUri("foo?abc:def"));
        assertFalse(Util.isAbsoluteUri("foo#abc:def"));
        assertFalse(Util.isAbsoluteUri("foo/bar"));
    }

    @Test
    @Issue("SECURITY-276")
    public void testIsSafeToRedirectTo() {
        assertFalse(Util.isSafeToRedirectTo("http://foobar/"));
        assertFalse(Util.isSafeToRedirectTo("mailto:kk@kohsuke.org"));
        assertFalse(Util.isSafeToRedirectTo("d123://test/"));
        assertFalse(Util.isSafeToRedirectTo("//google.com"));

        assertTrue(Util.isSafeToRedirectTo("foo/bar/abc:def"));
        assertTrue(Util.isSafeToRedirectTo("foo?abc:def"));
        assertTrue(Util.isSafeToRedirectTo("foo#abc:def"));
        assertTrue(Util.isSafeToRedirectTo("foo/bar"));
        assertTrue(Util.isSafeToRedirectTo("/"));
        assertTrue(Util.isSafeToRedirectTo("/foo"));
        assertTrue(Util.isSafeToRedirectTo(".."));
        assertTrue(Util.isSafeToRedirectTo("../.."));
        assertTrue(Util.isSafeToRedirectTo("/#foo"));
        assertTrue(Util.isSafeToRedirectTo("/?foo"));
    }

    @Test
    public void loadProperties() throws IOException {

        assertEquals(0, Util.loadProperties("").size());

        Properties p = Util.loadProperties("k.e.y=va.l.ue");
        assertEquals(p.toString(), "va.l.ue", p.get("k.e.y"));
        assertEquals(p.toString(), 1, p.size());
    }

    @Test
    public void isRelativePathUnix() {
        assertThat("/", not(aRelativePath()));
        assertThat("/foo/bar", not(aRelativePath()));
        assertThat("/foo/../bar", not(aRelativePath()));
        assertThat("", aRelativePath());
        assertThat(".", aRelativePath());
        assertThat("..", aRelativePath());
        assertThat("./foo", aRelativePath());
        assertThat("./foo/bar", aRelativePath());
        assertThat("./foo/bar/", aRelativePath());
    }

    @Test
    public void isRelativePathWindows() {
        assertThat("\\", aRelativePath());
        assertThat("\\foo\\bar", aRelativePath());
        assertThat("\\foo\\..\\bar", aRelativePath());
        assertThat("", aRelativePath());
        assertThat(".", aRelativePath());
        assertThat(".\\foo", aRelativePath());
        assertThat(".\\foo\\bar", aRelativePath());
        assertThat(".\\foo\\bar\\", aRelativePath());
        assertThat("\\\\foo", aRelativePath());
        assertThat("\\\\foo\\", not(aRelativePath()));
        assertThat("\\\\foo\\c", not(aRelativePath()));
        assertThat("C:", aRelativePath());
        assertThat("z:", aRelativePath());
        assertThat("0:", aRelativePath());
        assertThat("c:.", aRelativePath());
        assertThat("c:\\", not(aRelativePath()));
        assertThat("c:/", not(aRelativePath()));
    }

    private static RelativePathMatcher aRelativePath() {
        return new RelativePathMatcher();
    }

    private static class RelativePathMatcher extends BaseMatcher<String> {

        @Override
        public boolean matches(Object item) {
            return Util.isRelativePath((String) item);
        }

        @Override
        public void describeTo(Description description) {
            description.appendText("a relative path");
        }
    }

    @Test
    public void testIsDescendant() throws IOException {
        File root;
        File other;
        if (Functions.isWindows()) {
            root = new File("C:\\Temp");
            other = new File("C:\\Windows");
        } else {
            root = new File("/tmp");
            other = new File("/usr");

        }
        assertTrue(Util.isDescendant(root, new File(root,"child")));
        assertTrue(Util.isDescendant(root, new File(new File(root,"child"), "grandchild")));
        assertFalse(Util.isDescendant(root, other));
        assertFalse(Util.isDescendant(root, new File(other, "child")));

        assertFalse(Util.isDescendant(new File(root,"child"), root));
        assertFalse(Util.isDescendant(new File(new File(root,"child"), "grandchild"), root));

        //.. whithin root
        File convoluted = new File(root, "child");
        convoluted = new File(convoluted, "..");
        convoluted = new File(convoluted, "child");
        assertTrue(Util.isDescendant(root, convoluted));

        //.. going outside of root
        convoluted = new File(root, "..");
        convoluted = new File(convoluted, other.getName());
        convoluted = new File(convoluted, "child");
        assertFalse(Util.isDescendant(root, convoluted));

        //. on root
        assertTrue(Util.isDescendant(new File(root, "."), new File(root, "child")));
        //. on both
        assertTrue(Util.isDescendant(new File(root, "."), new File(new File(root, "child"), ".")));
    }

    @Test
    public void testModeToPermissions() throws Exception {
        assertEquals(PosixFilePermissions.fromString("rwxrwxrwx"), Util.modeToPermissions(0777));
        assertEquals(PosixFilePermissions.fromString("rwxr-xrwx"), Util.modeToPermissions(0757));
        assertEquals(PosixFilePermissions.fromString("rwxr-x---"), Util.modeToPermissions(0750));
        assertEquals(PosixFilePermissions.fromString("r-xr-x---"), Util.modeToPermissions(0550));
        assertEquals(PosixFilePermissions.fromString("r-xr-----"), Util.modeToPermissions(0540));
        assertEquals(PosixFilePermissions.fromString("--xr-----"), Util.modeToPermissions(0140));
        assertEquals(PosixFilePermissions.fromString("--xr---w-"), Util.modeToPermissions(0142));
        assertEquals(PosixFilePermissions.fromString("--xr--rw-"), Util.modeToPermissions(0146));
        assertEquals(PosixFilePermissions.fromString("-wxr--rw-"), Util.modeToPermissions(0346));
        assertEquals(PosixFilePermissions.fromString("---------"), Util.modeToPermissions(0000));

        assertEquals("Non-permission bits should be ignored", PosixFilePermissions.fromString("r-xr-----"), Util.modeToPermissions(0100540));

        expectedException.expectMessage(startsWith("Invalid mode"));
        Util.modeToPermissions(01777);
    }

    @Test
    public void testPermissionsToMode() throws Exception {
        assertEquals(0777, Util.permissionsToMode(PosixFilePermissions.fromString("rwxrwxrwx")));
        assertEquals(0757, Util.permissionsToMode(PosixFilePermissions.fromString("rwxr-xrwx")));
        assertEquals(0750, Util.permissionsToMode(PosixFilePermissions.fromString("rwxr-x---")));
        assertEquals(0550, Util.permissionsToMode(PosixFilePermissions.fromString("r-xr-x---")));
        assertEquals(0540, Util.permissionsToMode(PosixFilePermissions.fromString("r-xr-----")));
        assertEquals(0140, Util.permissionsToMode(PosixFilePermissions.fromString("--xr-----")));
        assertEquals(0142, Util.permissionsToMode(PosixFilePermissions.fromString("--xr---w-")));
        assertEquals(0146, Util.permissionsToMode(PosixFilePermissions.fromString("--xr--rw-")));
        assertEquals(0346, Util.permissionsToMode(PosixFilePermissions.fromString("-wxr--rw-")));
        assertEquals(0000, Util.permissionsToMode(PosixFilePermissions.fromString("---------")));
    }

    @Test
    public void testDifferenceDays() throws Exception {
        Date may_6_10am = parseDate("2018-05-06 10:00:00"); 
        Date may_6_11pm55 = parseDate("2018-05-06 23:55:00"); 
        Date may_7_01am = parseDate("2018-05-07 01:00:00"); 
        Date may_7_11pm = parseDate("2018-05-07 11:00:00"); 
        Date may_8_08am = parseDate("2018-05-08 08:00:00"); 
        Date june_3_08am = parseDate("2018-06-03 08:00:00"); 
        Date june_9_08am = parseDate("2018-06-09 08:00:00"); 
        Date june_9_08am_nextYear = parseDate("2019-06-09 08:00:00"); 
        
        assertEquals(0, Util.daysBetween(may_6_10am, may_6_11pm55));
        assertEquals(1, Util.daysBetween(may_6_10am, may_7_01am));
        assertEquals(1, Util.daysBetween(may_6_11pm55, may_7_01am));
        assertEquals(2, Util.daysBetween(may_6_10am, may_8_08am));
        assertEquals(1, Util.daysBetween(may_7_11pm, may_8_08am));
        
        // larger scale
        assertEquals(28, Util.daysBetween(may_6_10am, june_3_08am));
        assertEquals(34, Util.daysBetween(may_6_10am, june_9_08am));
        assertEquals(365 + 34, Util.daysBetween(may_6_10am, june_9_08am_nextYear));
        
        // reverse order
        assertEquals(-1, Util.daysBetween(may_8_08am, may_7_11pm));
    }
    
    private Date parseDate(String dateString) throws ParseException {
        return new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").parse(dateString);
    }

    @Test
    @Issue("SECURITY-904")
    public void resolveSymlinkToFile() throws Exception {
        //  root
        //      /a
        //          /aa
        //              aa.txt
        //          /_b => symlink to /root/b
        //      /b
        //          /_a => symlink to /root/a
        File root = tmp.getRoot();
        File a = new File(root, "a");
        File aa = new File(a, "aa");
        aa.mkdirs();
        File aaTxt = new File(aa, "aa.txt");
        FileUtils.write(aaTxt, "aa");

        File b = new File(root, "b");
        b.mkdir();

        File _a = new File(b, "_a");
        Util.createSymlink(_a.getParentFile(), a.getAbsolutePath(), _a.getName(), TaskListener.NULL);

        File _b = new File(a, "_b");
        Util.createSymlink(_b.getParentFile(), b.getAbsolutePath(), _b.getName(), TaskListener.NULL);

        assertTrue(Files.isSymbolicLink(_a.toPath()));
        assertTrue(Files.isSymbolicLink(_b.toPath()));

        // direct symlinks are resolved
        assertEquals(Util.resolveSymlinkToFile(_a), a);
        assertEquals(Util.resolveSymlinkToFile(_b), b);

        // intermediate symlinks are NOT resolved
        assertNull(Util.resolveSymlinkToFile(new File(_a, "aa")));
        assertNull(Util.resolveSymlinkToFile(new File(_a, "aa/aa.txt")));
    }
}