1 /*
   2  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 import java.nio.CharBuffer;
  25 import java.util.Iterator;
  26 import java.util.Set;
  27 import java.util.TreeSet;
  28 import org.testng.Assert;
  29 import org.testng.annotations.Test;
  30 
  31 /**
  32  * @test
  33  * @bug 8215401
  34  * @summary Test to verify the isEmpty method is behaviorally consistent
  35  *          with length
  36  * @run testng Emptiness
  37  */
  38 public class Emptiness {
  39 
  40     @Test
  41     public void isEmpty() {
  42         checkEmpty(new StringBuilder());
  43         checkEmpty(new StringBuffer());
  44         checkEmpty("");
  45         checkEmpty(new CharSequence() {
  46             @Override public int length() { return 0; }
  47             @Override public char charAt(int index) { return 'f'; }
  48             @Override public CharSequence subSequence(int start, int end) {
  49                 throw new UnsupportedOperationException();
  50             }
  51         });
  52     }
  53 
  54     @Test
  55     public void isNotEmpty() {
  56         checkNotEmpty(new StringBuilder().append("foo"));
  57         checkNotEmpty(new StringBuffer().append("bar"));
  58         checkNotEmpty("baz");
  59         checkNotEmpty(new CharSequence() {
  60             @Override public int length() { return 1; }
  61             @Override public char charAt(int index) { return 'f'; }
  62             @Override public CharSequence subSequence(int start, int end) {
  63                 throw new UnsupportedOperationException();
  64             }
  65         });
  66     }
  67 
  68     public void checkEmpty(CharSequence cs) {
  69         Assert.assertTrue(cs.isEmpty());
  70         Assert.assertTrue(consistentWithLength(cs));
  71     }
  72 
  73     public void checkNotEmpty(CharSequence cs) {
  74         Assert.assertTrue(!cs.isEmpty());
  75         Assert.assertTrue(consistentWithLength(cs));
  76     }
  77 
  78     public boolean consistentWithLength(CharSequence cs) {
  79         return cs.isEmpty() == (cs.length() == 0);
  80     }
  81 }