From 05cc3dbd3af33bcc58b6882913dcc139e4189a98 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Tue, 27 Dec 2022 17:35:10 +0400
Subject: [PATCH] Add tests

---
 src/string.c   |  7 +++-
 tests/string.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/src/string.c b/src/string.c
index 437a2ec..9d54b15 100644
--- a/src/string.c
+++ b/src/string.c
@@ -106,7 +106,12 @@ char *LIBCLAYER(strncat)(char *dest, const char *src, size_t n)
 
 int LIBCLAYER(strncmp)(const char *s1, const char *s2, size_t n)
 {
-    for (; *s1 && n; ++s1, ++s2, --n) if (*s1 != *s2) return *s1 < *s2 ? -1 : 1;
+    while (n--) {
+        const char c1 = *s1++;
+        const char c2 = *s2++;
+        if (c1 != c2) return c1 < c2 ? -1 : 1;
+        if (!c1) return 0;
+    }
     return 0;
 }
 
diff --git a/tests/string.c b/tests/string.c
index 5e0d7f4..0dc54f5 100644
--- a/tests/string.c
+++ b/tests/string.c
@@ -19,6 +19,11 @@ static char aaa[COUNT], bbb[COUNT];
 #define strcpy  LIBCLAYER(strcpy)
 #define strlen  LIBCLAYER(strlen)
 
+#define strncat LIBCLAYER(strncat)
+#define strncmp LIBCLAYER(strncmp)
+#define strncpy LIBCLAYER(strncpy)
+#define strnlen LIBCLAYER(strnlen)
+
 void test_main()
 {
     { // memcmp
@@ -97,4 +102,88 @@ void test_main()
         assert(strlen("aa") == 2);
         assert(strlen("aaaaaaaaaa") == 10);
     }
+
+    { // strncat
+        memset(aaa, '\x01', COUNT);
+        aaa[0] = 'f'; aaa[1] = 'o'; aaa[2] = 'o'; aaa[3] = '\0';
+        strncat(aaa, "bar", 4);
+        for (const char *e = "foobar", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[6] == '\0');
+
+        memset(aaa, '\x01', COUNT);
+        aaa[0] = 'f'; aaa[1] = 'o'; aaa[2] = 'o'; aaa[3] = '\0';
+        strncat(aaa, "bar", 3);
+        for (const char *e = "foobar", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[6] == '\0');
+
+        memset(aaa, '\x01', COUNT);
+        aaa[0] = 'f'; aaa[1] = 'o'; aaa[2] = 'o'; aaa[3] = '\0';
+        strncat(aaa, "bar", 2);
+        for (const char *e = "fooba", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[5] == '\0');
+
+        memset(aaa, '\x01', COUNT);
+        aaa[0] = 'f'; aaa[1] = 'o'; aaa[2] = 'o'; aaa[3] = '\0';
+        strncat(aaa, "bar", 1);
+        for (const char *e = "foob", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[4] == '\0');
+
+        memset(aaa, '\x01', COUNT);
+        aaa[0] = 'f'; aaa[1] = 'o'; aaa[2] = 'o'; aaa[3] = '\0';
+        strncat(aaa, "bar", 0);
+        for (const char *e = "foo", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[3] == '\0');
+    }
+
+    { // strncmp
+        assert(strncmp("", "", 0) == 0);
+        assert(strncmp("", "a", 0) == 0);
+        assert(strncmp("a", "", 0) == 0);
+        assert(strncmp("a", "a", 0) == 0);
+        assert(strncmp("", "a", 1) == -1);
+        assert(strncmp("a", "", 1) == 1);
+        assert(strncmp("a", "a", 1) == 0);
+        assert(strncmp("a", "aa", 1) == 0);
+        assert(strncmp("aa", "a", 1) == 0);
+        assert(strncmp("aa", "ab", 1) == 0);
+        assert(strncmp("ab", "aa", 1) == 0);
+        assert(strncmp("aa", "aa", 1) == 0);
+        assert(strncmp("aa", "ba", 1) == -1);
+        assert(strncmp("ba", "aa", 1) == 1);
+        assert(strncmp("ab", "ab", 1) == 0);
+        assert(strncmp("a", "aa", 2) == -1);
+        assert(strncmp("aa", "a", 2) == 1);
+        assert(strncmp("aa", "ab", 2) == -1);
+        assert(strncmp("ab", "aa", 2) == 1);
+        assert(strncmp("aa", "aa", 2) == 0);
+    }
+
+    { // strncpy
+        aaa[6] = 'x';
+        assert(strncpy(aaa, "foobar", 7) == aaa);
+        for (const char *e = "foobar", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[6] == '\0');
+
+        aaa[6] = 'x';
+        assert(strncpy(aaa, "foobar", 6) == aaa);
+        for (const char *e = "foobar", *g = aaa; *e; ++e, ++g) assert(*g == *e);
+        assert(aaa[6] == 'x');
+    }
+
+    { // strnlen
+        assert(strnlen("", 0) == 0);
+        assert(strnlen("", 1) == 0);
+        assert(strnlen("", 123) == 0);
+        assert(strnlen("a", 0) == 0);
+        assert(strnlen("a", 1) == 1);
+        assert(strnlen("a", 123) == 1);
+        assert(strnlen("aa", 0) == 0);
+        assert(strnlen("aa", 1) == 1);
+        assert(strnlen("aa", 2) == 2);
+        assert(strnlen("aa", 123) == 2);
+        assert(strnlen("aaaaaaaaaa", 0) == 0);
+        assert(strnlen("aaaaaaaaaa", 9) == 9);
+        assert(strnlen("aaaaaaaaaa", 10) == 10);
+        assert(strnlen("aaaaaaaaaa", 123) == 10);
+    }
 }