1 /*
2 * Copyright (c) 2011-2025 Yegor Bugayenko
3 *
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met: 1) Redistributions of source code must retain the above
9 * copyright notice, this list of conditions and the following
10 * disclaimer. 2) Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following
12 * disclaimer in the documentation and/or other materials provided
13 * with the distribution. 3) Neither the name of the Qulice.com nor
14 * the names of its contributors may be used to endorse or promote
15 * products derived from this software without specific prior written
16 * permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
20 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
22 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
23 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29 * OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31 package com.qulice.pmd;
32
33 import org.hamcrest.Matcher;
34 import org.hamcrest.core.CombinableMatcher;
35 import org.hamcrest.core.IsEqual;
36 import org.hamcrest.core.StringContains;
37 import org.hamcrest.text.IsEmptyString;
38 import org.junit.jupiter.api.Test;
39 import org.junit.jupiter.params.ParameterizedTest;
40 import org.junit.jupiter.params.provider.ValueSource;
41
42 /**
43 * Test case for {@link com.qulice.pmd.rules.UseStringIsEmptyRule}.
44 * @since 0.18
45 */
46 final class UseStringIsEmptyRuleTest {
47
48 /**
49 * UseStringIsEmpty can detect when used String.length(), when checking for
50 * empty string.
51 * @param file File name.
52 * @throws Exception If something goes wrong.
53 */
54 @ParameterizedTest
55 @ValueSource(
56 strings = {
57 "StringLengthGreaterThanZero.java",
58 "StringLengthGreaterOrEqualZero.java",
59 "StringLengthGreaterOrEqualOne.java",
60 "StringLengthLessThanOne.java",
61 "StringLengthLessOrEqualZero.java",
62 "StringLengthEqualsZero.java",
63 "StringLengthNotEqualsZero.java"
64 }
65 )
66 void detectLengthComparisons(final String file) throws Exception {
67 new PmdAssert(
68 file, new IsEqual<>(false),
69 new CombinableMatcher<>(containsMatcher(file, 46))
70 .and(containsMatcher(file, 50))
71 .and(containsMatcher(file, 54))
72 .and(containsMatcher(file, 58))
73 .and(containsMatcher(file, 62))
74 ).validate();
75 }
76
77 /**
78 * UseStringIsEmpty not detect when used String[].length, when checking for
79 * empty string.
80 * @throws Exception If something goes wrong.
81 */
82 @Test
83 void notDetectOnArrayOfStrings() throws Exception {
84 new PmdAssert(
85 "ArrayOfStringsLengthGreaterThanZero.java",
86 new IsEqual<>(true),
87 IsEmptyString.emptyString()
88 ).validate();
89 }
90
91 /**
92 * Constructs StringContains matcher for error message.
93 * @param file File name.
94 * @param line Line number.
95 * @return StringContains matcher.
96 */
97 private static Matcher<String> containsMatcher(
98 final String file, final int line
99 ) {
100 final String message =
101 "Use String.isEmpty() when checking for empty string";
102 return new StringContains(
103 String.format(
104 "PMD: %1$s[%2$d-%2$d]: %3$s (UseStringIsEmptyRule)",
105 file, line, message
106 )
107 );
108 }
109 }