1 //===-- Unittests for strncmp ---------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "src/string/strncmp.h"
10 #include "utils/UnitTest/Test.h"
11 
12 // This group is just copies of the strcmp tests, since all the same cases still
13 // need to be tested.
14 
15 TEST(LlvmLibcStrNCmpTest, EmptyStringsShouldReturnZeroWithSufficientLength) {
16   const char *s1 = "";
17   const char *s2 = "";
18   int result = __llvm_libc::strncmp(s1, s2, 1);
19   ASSERT_EQ(result, 0);
20 
21   // Verify operands reversed.
22   result = __llvm_libc::strncmp(s2, s1, 1);
23   ASSERT_EQ(result, 0);
24 }
25 
26 TEST(LlvmLibcStrNCmpTest,
27      EmptyStringShouldNotEqualNonEmptyStringWithSufficientLength) {
28   const char *empty = "";
29   const char *s2 = "abc";
30   int result = __llvm_libc::strncmp(empty, s2, 3);
31   // This should be '\0' - 'a' = -97
32   ASSERT_EQ(result, -97);
33 
34   // Similar case if empty string is second argument.
35   const char *s3 = "123";
36   result = __llvm_libc::strncmp(s3, empty, 3);
37   // This should be '1' - '\0' = 49
38   ASSERT_EQ(result, 49);
39 }
40 
41 TEST(LlvmLibcStrNCmpTest, EqualStringsShouldReturnZeroWithSufficientLength) {
42   const char *s1 = "abc";
43   const char *s2 = "abc";
44   int result = __llvm_libc::strncmp(s1, s2, 3);
45   ASSERT_EQ(result, 0);
46 
47   // Verify operands reversed.
48   result = __llvm_libc::strncmp(s2, s1, 3);
49   ASSERT_EQ(result, 0);
50 }
51 
52 TEST(LlvmLibcStrNCmpTest,
53      ShouldReturnResultOfFirstDifferenceWithSufficientLength) {
54   const char *s1 = "___B42__";
55   const char *s2 = "___C55__";
56   int result = __llvm_libc::strncmp(s1, s2, 8);
57   // This should return 'B' - 'C' = -1.
58   ASSERT_EQ(result, -1);
59 
60   // Verify operands reversed.
61   result = __llvm_libc::strncmp(s2, s1, 8);
62   // This should return 'C' - 'B' = 1.
63   ASSERT_EQ(result, 1);
64 }
65 
66 TEST(LlvmLibcStrNCmpTest,
67      CapitalizedLetterShouldNotBeEqualWithSufficientLength) {
68   const char *s1 = "abcd";
69   const char *s2 = "abCd";
70   int result = __llvm_libc::strncmp(s1, s2, 4);
71   // 'c' - 'C' = 32.
72   ASSERT_EQ(result, 32);
73 
74   // Verify operands reversed.
75   result = __llvm_libc::strncmp(s2, s1, 4);
76   // 'C' - 'c' = -32.
77   ASSERT_EQ(result, -32);
78 }
79 
80 TEST(LlvmLibcStrNCmpTest,
81      UnequalLengthStringsShouldNotReturnZeroWithSufficientLength) {
82   const char *s1 = "abc";
83   const char *s2 = "abcd";
84   int result = __llvm_libc::strncmp(s1, s2, 4);
85   // '\0' - 'd' = -100.
86   ASSERT_EQ(result, -100);
87 
88   // Verify operands reversed.
89   result = __llvm_libc::strncmp(s2, s1, 4);
90   // 'd' - '\0' = 100.
91   ASSERT_EQ(result, 100);
92 }
93 
94 TEST(LlvmLibcStrNCmpTest, StringArgumentSwapChangesSignWithSufficientLength) {
95   const char *a = "a";
96   const char *b = "b";
97   int result = __llvm_libc::strncmp(b, a, 1);
98   // 'b' - 'a' = 1.
99   ASSERT_EQ(result, 1);
100 
101   result = __llvm_libc::strncmp(a, b, 1);
102   // 'a' - 'b' = -1.
103   ASSERT_EQ(result, -1);
104 }
105 
106 // This group is actually testing strncmp functionality
107 
108 TEST(LlvmLibcStrNCmpTest, NonEqualStringsEqualWithLengthZero) {
109   const char *s1 = "abc";
110   const char *s2 = "def";
111   int result = __llvm_libc::strncmp(s1, s2, 0);
112   ASSERT_EQ(result, 0);
113 
114   // Verify operands reversed.
115   result = __llvm_libc::strncmp(s2, s1, 0);
116   ASSERT_EQ(result, 0);
117 }
118 
119 TEST(LlvmLibcStrNCmpTest, NonEqualStringsNotEqualWithLengthOne) {
120   const char *s1 = "abc";
121   const char *s2 = "def";
122   int result = __llvm_libc::strncmp(s1, s2, 1);
123   ASSERT_EQ(result, -3);
124 
125   // Verify operands reversed.
126   result = __llvm_libc::strncmp(s2, s1, 1);
127   ASSERT_EQ(result, 3);
128 }
129 
130 TEST(LlvmLibcStrNCmpTest, NonEqualStringsEqualWithShorterLength) {
131   const char *s1 = "___B42__";
132   const char *s2 = "___C55__";
133   int result = __llvm_libc::strncmp(s1, s2, 3);
134   ASSERT_EQ(result, 0);
135 
136   // This should return 'B' - 'C' = -1.
137   result = __llvm_libc::strncmp(s1, s2, 4);
138   ASSERT_EQ(result, -1);
139 
140   // Verify operands reversed.
141   result = __llvm_libc::strncmp(s2, s1, 3);
142   ASSERT_EQ(result, 0);
143 
144   // This should return 'C' - 'B' = 1.
145   result = __llvm_libc::strncmp(s2, s1, 4);
146   ASSERT_EQ(result, 1);
147 }
148 
149 TEST(LlvmLibcStrNCmpTest, StringComparisonEndsOnNullByteEvenWithLongerLength) {
150   const char *s1 = "abc\0def";
151   const char *s2 = "abc\0abc";
152   int result = __llvm_libc::strncmp(s1, s2, 7);
153   ASSERT_EQ(result, 0);
154 
155   // Verify operands reversed.
156   result = __llvm_libc::strncmp(s2, s1, 7);
157   ASSERT_EQ(result, 0);
158 }
159