unit-tests: rewrite t/helper/test-ctype.c as a unit test

In the recent codebase update (8bf6fbd (Merge branch
'js/doc-unit-tests', 2023-12-09)), a new unit testing framework was
merged, providing a standardized approach for testing C code. Prior to
this update, some unit tests relied on the test helper mechanism,
lacking a dedicated unit testing framework. It's more natural to perform
these unit tests using the new unit test framework.

This commit migrates the unit tests for C character classification
functions (isdigit(), isspace(), etc) from the legacy approach
using the test-tool command `test-tool ctype` in t/helper/test-ctype.c
to the new unit testing framework (t/unit-tests/test-lib.h).

The migration involves refactoring the tests to utilize the testing
macros provided by the framework (TEST() and check_*()).

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Helped-by: René Scharfe <l.s.r@web.de>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Helped-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Achu Luma <ach.lumap@gmail.com>
Acked-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -792,7 +792,6 @@ TEST_BUILTINS_OBJS += test-chmtime.o
 TEST_BUILTINS_OBJS += test-config.o
 TEST_BUILTINS_OBJS += test-crontab.o
 TEST_BUILTINS_OBJS += test-csprng.o
-TEST_BUILTINS_OBJS += test-ctype.o
 TEST_BUILTINS_OBJS += test-date.o
 TEST_BUILTINS_OBJS += test-delta.o
 TEST_BUILTINS_OBJS += test-dir-iterator.o
@@ -1341,6 +1340,7 @@ THIRD_PARTY_SOURCES += sha1dc/%
 
 UNIT_TEST_PROGRAMS += t-basic
 UNIT_TEST_PROGRAMS += t-strbuf
+UNIT_TEST_PROGRAMS += t-ctype
 UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_BIN)/%$X,$(UNIT_TEST_PROGRAMS))
 UNIT_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o

t/helper/test-tool.c

@@ -19,7 +19,6 @@ static struct test_cmd cmds[] = {
 	{ "config", cmd__config },
 	{ "crontab", cmd__crontab },
 	{ "csprng", cmd__csprng },
-	{ "ctype", cmd__ctype },
 	{ "date", cmd__date },
 	{ "delta", cmd__delta },
 	{ "dir-iterator", cmd__dir_iterator },

t/helper/test-tool.h

@@ -12,7 +12,6 @@ int cmd__chmtime(int argc, const char **argv);
 int cmd__config(int argc, const char **argv);
 int cmd__crontab(int argc, const char **argv);
 int cmd__csprng(int argc, const char **argv);
-int cmd__ctype(int argc, const char **argv);
 int cmd__date(int argc, const char **argv);
 int cmd__delta(int argc, const char **argv);
 int cmd__dir_iterator(int argc, const char **argv);

t/t0070-fundamental.sh

@@ -9,10 +9,6 @@ Verify wrappers and compatibility functions.
 TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
-test_expect_success 'character classes (isspace, isalpha etc.)' '
-	test-tool ctype
-'
-
 test_expect_success 'mktemp to nonexistent directory prints filename' '
 	test_must_fail test-tool mktemp doesnotexist/testXXXXXX 2>err &&
 	grep "doesnotexist/test" err

t/unit-tests/t-ctype.c

@@ -0,0 +1,80 @@
+#include "test-lib.h"
+
+static int is_in(const char *s, int ch)
+{
+	/*
+	 * We can't find NUL using strchr. Accept it as the first
+	 * character in the spec -- there are no empty classes.
+	 */
+	if (ch == '\0')
+		return ch == *s;
+	if (*s == '\0')
+		s++;
+	return !!strchr(s, ch);
+}
+
+/* Macro to test a character type */
+#define TEST_CTYPE_FUNC(func, string) \
+static void test_ctype_##func(void) { \
+	for (int i = 0; i < 256; i++) { \
+		if (!check_int(func(i), ==, is_in(string, i))) \
+			test_msg("       i: 0x%02x", i); \
+	} \
+	if (!check(!func(EOF))) \
+			test_msg("      i: 0x%02x (EOF)", EOF); \
+}
+
+#define TEST_CHAR_CLASS(class) TEST(test_ctype_##class(), #class " works")
+
+#define DIGIT "0123456789"
+#define LOWER "abcdefghijklmnopqrstuvwxyz"
+#define UPPER "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+#define PUNCT "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~"
+#define ASCII \
+	"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" \
+	"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f" \
+	"\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f" \
+	"\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f" \
+	"\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f" \
+	"\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f" \
+	"\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f" \
+	"\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f"
+#define CNTRL \
+	"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" \
+	"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f" \
+	"\x7f"
+
+TEST_CTYPE_FUNC(isdigit, DIGIT)
+TEST_CTYPE_FUNC(isspace, " \n\r\t")
+TEST_CTYPE_FUNC(isalpha, LOWER UPPER)
+TEST_CTYPE_FUNC(isalnum, LOWER UPPER DIGIT)
+TEST_CTYPE_FUNC(is_glob_special, "*?[\\")
+TEST_CTYPE_FUNC(is_regex_special, "$()*+.?[\\^{|")
+TEST_CTYPE_FUNC(is_pathspec_magic, "!\"#%&',-/:;<=>@_`~")
+TEST_CTYPE_FUNC(isascii, ASCII)
+TEST_CTYPE_FUNC(islower, LOWER)
+TEST_CTYPE_FUNC(isupper, UPPER)
+TEST_CTYPE_FUNC(iscntrl, CNTRL)
+TEST_CTYPE_FUNC(ispunct, PUNCT)
+TEST_CTYPE_FUNC(isxdigit, DIGIT "abcdefABCDEF")
+TEST_CTYPE_FUNC(isprint, LOWER UPPER DIGIT PUNCT " ")
+
+int cmd_main(int argc, const char **argv) {
+	/* Run all character type tests */
+	TEST_CHAR_CLASS(isspace);
+	TEST_CHAR_CLASS(isdigit);
+	TEST_CHAR_CLASS(isalpha);
+	TEST_CHAR_CLASS(isalnum);
+	TEST_CHAR_CLASS(is_glob_special);
+	TEST_CHAR_CLASS(is_regex_special);
+	TEST_CHAR_CLASS(is_pathspec_magic);
+	TEST_CHAR_CLASS(isascii);
+	TEST_CHAR_CLASS(islower);
+	TEST_CHAR_CLASS(isupper);
+	TEST_CHAR_CLASS(iscntrl);
+	TEST_CHAR_CLASS(ispunct);
+	TEST_CHAR_CLASS(isxdigit);
+	TEST_CHAR_CLASS(isprint);
+
+	return test_done();
+}