wcscmp: Add tests.

* tests/test-wcscmp.c: New file, based on tests/unistr/test-strcmp.h.
* modules/wcscmp-tests: New file.

ChangeLog

@@ -1,5 +1,9 @@
 2023-04-18  Bruno Haible  <bruno@clisp.org>
 
+	wcscmp: Add tests.
+	* tests/test-wcscmp.c: New file, based on tests/unistr/test-strcmp.h.
+	* modules/wcscmp-tests: New file.
+
 	wcscmp: Work around two ISO C compliance bugs on several platforms.
 	* lib/wchar.in.h (wcscmp): Consider REPLACE_WCSCMP.
 	* lib/wcscmp-impl.h (wcscmp): Don't assume that the two wide characters

modules/wcscmp-tests

@@ -0,0 +1,12 @@
+Files:
+tests/test-wcscmp.c
+tests/signature.h
+tests/macros.h
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-wcscmp
+check_PROGRAMS += test-wcscmp

tests/test-wcscmp.c

@@ -0,0 +1,122 @@
+/* Test of wcscmp() function.
+   Copyright (C) 2010-2023 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2023.  */
+
+#include <config.h>
+
+#include <wchar.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (wcscmp, int, (const wchar_t *, const wchar_t *));
+
+#include "macros.h"
+
+int
+main (int argc, char *argv[])
+{
+  /* Test simple cases.  */
+  {
+    static const wchar_t input1[] = { 0 };
+    static const wchar_t input2[] = { 0 };
+    ASSERT (wcscmp (input1, input2) == 0);
+  }
+  {
+    static const wchar_t input1[] = { 0 };
+    static const wchar_t input2[] = { 'f', 'o', 'o', 0 };
+    ASSERT (wcscmp (input1, input2) < 0);
+    ASSERT (wcscmp (input2, input1) > 0);
+  }
+  {
+    static const wchar_t input1[] = { 'f', 'o', 'o', 0 };
+    static const wchar_t input2[] = { 'f', 'o', 'o', 0 };
+    ASSERT (wcscmp (input1, input2) == 0);
+  }
+  {
+    static const wchar_t input1[] = { 'f', 'o', 'o', 0 };
+    static const wchar_t input2[] = { 'b', 'a', 'r', 0 };
+    ASSERT (wcscmp (input1, input2) > 0);
+    ASSERT (wcscmp (input2, input1) < 0);
+  }
+  {
+    static const wchar_t input1[] = { 'f', 'o', 'o', 0 };
+    static const wchar_t input2[] = { 'f', 'o', 'o', 'b', 'a', 'r', 0 };
+    ASSERT (wcscmp (input1, input2) < 0);
+    ASSERT (wcscmp (input2, input1) > 0);
+  }
+  {
+    static const wchar_t input1[] = { 'o', 'o', 'm', 'p', 'h', 0 };
+    static const wchar_t input2[] = { 'o', 'o', 'p', 's', 0 };
+    ASSERT (wcscmp (input1, input2) < 0);
+    ASSERT (wcscmp (input2, input1) > 0);
+  }
+
+  /* ISO C requires wcscmp to work with all wchar_t values.
+     ISO C 17 § 7.29.4.4 says:
+       "Unless explicitly stated otherwise, the functions described in this
+        subclause order two wide characters the same way as two integers of
+        the underlying integer type designated by wchar_t."  */
+  {
+    static const wchar_t input1[] = { (wchar_t) 0x76547654, 0 };
+    static const wchar_t input2[] = { (wchar_t) 0x9abc9abc, 0 };
+    if ((wchar_t)-1 < 0)
+      {
+        /* wchar_t is signed.  */
+        ASSERT (wcscmp (input1, input2) > 0);
+        ASSERT (wcscmp (input2, input1) < 0);
+      }
+    else
+      {
+        /* wchar_t is unsigned.  */
+        ASSERT (wcscmp (input1, input2) < 0);
+        ASSERT (wcscmp (input2, input1) > 0);
+      }
+  }
+  {
+    static const wchar_t input1[] = { (wchar_t) 0x9abc9abc, 0 };
+    static const wchar_t input2[] = { (wchar_t) 0x9bdf9bdf, 0 };
+    ASSERT (wcscmp (input1, input2) < 0);
+    ASSERT (wcscmp (input2, input1) > 0);
+  }
+
+  /* Comparing a negative wchar_t value against a null wchar_t.
+     ISO C 17 § 7.29.4.4.1 says:
+       "The wcscmp function compares the wide string pointed to by s1 to
+        the wide string pointed to by s2."
+     ISO C 17 § 7.1.1 defines the term "wide string":
+       "A wide string is a contiguous sequence of wide characters terminated
+        by and including the first null wide character."
+     This means that the comparison extends up to and *including* the first
+     null wchar_t.  */
+  {
+    static const wchar_t input1[] = { (wchar_t) 'x', 0 };
+    static const wchar_t input2[] = { (wchar_t) 'x', (wchar_t) 0x9abc9abc, 0 };
+    if ((wchar_t)-1 < 0)
+      {
+        /* wchar_t is signed.  */
+        ASSERT (wcscmp (input1, input2) > 0);
+        ASSERT (wcscmp (input2, input1) < 0);
+      }
+    else
+      {
+        /* wchar_t is unsigned.  */
+        ASSERT (wcscmp (input1, input2) < 0);
+        ASSERT (wcscmp (input2, input1) > 0);
+      }
+  }
+
+  return 0;
+}