unistr/u*strstr tests: Add more tests

[Bruno Haible]

In <https://lists.gnu.org/archive/html/bug-gnulib/2018-09/msg00070.html>
and <https://lists.gnu.org/archive/html/bug-gnulib/2023-03/msg00129.html>
I added more tests to tests/test-strstr.c.

With this patch, I'm adding the same tests also to the libunistring *strstr
modules.


2023-04-02  Bruno Haible  <bruno@clisp.org>

        unistr/u*strstr tests: Add more tests.
        * tests/unistr/test-u-strstr.h (test_u_strstr): Add the two latest tests
        from tests/test-strstr.c.
        * tests/unistr/test-u8-strstr.c (U_SET): New macro.
        * tests/unistr/test-u16-strstr.c (U_SET): New macro.
        * tests/unistr/test-u32-strstr.c (U_SET): New macro.
        * modules/unistr/u8-strstr-tests (Depends-on): Add unistr/u8-set.
        * modules/unistr/u16-strstr-tests (Depends-on): Add unistr/u16-set.
        * modules/unistr/u32-strstr-tests (Depends-on): Add unistr/u32-set.

diff --git a/modules/unistr/u16-strstr-tests b/modules/unistr/u16-strstr-tests
index 5c3cfbff8d..3e77e8af4a 100644
--- a/modules/unistr/u16-strstr-tests
+++ b/modules/unistr/u16-strstr-tests
@@ -4,6 +4,7 @@ tests/unistr/test-u-strstr.h
 tests/macros.h
 
 Depends-on:
+unistr/u16-set
 
 configure.ac:
 AC_CHECK_DECLS_ONCE([alarm])
diff --git a/modules/unistr/u32-strstr-tests b/modules/unistr/u32-strstr-tests
index 8ec3124225..bccd5e602f 100644
--- a/modules/unistr/u32-strstr-tests
+++ b/modules/unistr/u32-strstr-tests
@@ -4,6 +4,7 @@ tests/unistr/test-u-strstr.h
 tests/macros.h
 
 Depends-on:
+unistr/u32-set
 
 configure.ac:
 AC_CHECK_DECLS_ONCE([alarm])
diff --git a/modules/unistr/u8-strstr-tests b/modules/unistr/u8-strstr-tests
index fdc7b76e12..23336d2184 100644
--- a/modules/unistr/u8-strstr-tests
+++ b/modules/unistr/u8-strstr-tests
@@ -4,6 +4,7 @@ tests/unistr/test-u-strstr.h
 tests/macros.h
 
 Depends-on:
+unistr/u8-set
 
 configure.ac:
 AC_CHECK_DECLS_ONCE([alarm])
diff --git a/tests/unistr/test-u-strstr.h b/tests/unistr/test-u-strstr.h
index b97badc005..639b3d9112 100644
--- a/tests/unistr/test-u-strstr.h
+++ b/tests/unistr/test-u-strstr.h
@@ -207,4 +207,42 @@ test_u_strstr (void)
     free (needle);
     free (haystack);
   }
+
+  /* Test case from Yves Bastide.
+     <https://www.openwall.com/lists/musl/2014/04/18/2>  */
+  {
+    const UNIT input[] =
+      { 'p', 'l', 'a', 'y', 'i', 'n', 'g', ' ', 'p', 'l', 'a', 'y', ' ', 'p',
+        'l', 'a', 'y', ' ', 'p', 'l', 'a', 'y', ' ', 'a', 'l', 'w', 'a', 'y',
+        's', 0
+      };
+    const UNIT needle[] =
+      { 'p', 'l', 'a', 'y', ' ', 'p', 'l', 'a', 'y', ' ', 'p', 'l', 'a', 'y',
+        0
+      };
+    const UNIT *result = U_STRSTR (input, needle);
+    ASSERT (result == input + 8);
+  }
+
+  /* Test long needles.  */
+  {
+    size_t m = 1024;
+    UNIT *haystack = (UNIT *) malloc ((2 * m + 1) * sizeof (UNIT));
+    UNIT *needle = (UNIT *) malloc ((m + 1) * sizeof (UNIT));
+    if (haystack != NULL && needle != NULL)
+      {
+        const UNIT *p;
+        haystack[0] = 'x';
+        U_SET (haystack + 1, ' ', m - 1);
+        U_SET (haystack + m, 'x', m);
+        haystack[2 * m] = '\0';
+        U_SET (needle, 'x', m);
+        needle[m] = '\0';
+        p = U_STRSTR (haystack, needle);
+        ASSERT (p);
+        ASSERT (p - haystack == m);
+      }
+    free (needle);
+    free (haystack);
+  }
 }
diff --git a/tests/unistr/test-u16-strstr.c b/tests/unistr/test-u16-strstr.c
index b5cd028ff6..9c49aa0496 100644
--- a/tests/unistr/test-u16-strstr.c
+++ b/tests/unistr/test-u16-strstr.c
@@ -29,6 +29,7 @@
 
 #define UNIT uint16_t
 #define U_STRSTR u16_strstr
+#define U_SET u16_set
 #include "test-u-strstr.h"
 
 int
diff --git a/tests/unistr/test-u32-strstr.c b/tests/unistr/test-u32-strstr.c
index 9f388127a5..134a3c5366 100644
--- a/tests/unistr/test-u32-strstr.c
+++ b/tests/unistr/test-u32-strstr.c
@@ -29,6 +29,7 @@
 
 #define UNIT uint32_t
 #define U_STRSTR u32_strstr
+#define U_SET u32_set
 #include "test-u-strstr.h"
 
 int
diff --git a/tests/unistr/test-u8-strstr.c b/tests/unistr/test-u8-strstr.c
index f11d9408c2..39f831b2ea 100644
--- a/tests/unistr/test-u8-strstr.c
+++ b/tests/unistr/test-u8-strstr.c
@@ -29,6 +29,7 @@
 
 #define UNIT uint8_t
 #define U_STRSTR u8_strstr
+#define U_SET u8_set
 #include "test-u-strstr.h"
 
 int