t/unit-tests: convert strcmp-offset test to use clar test framework

Adapt strcmp-offset test script to clar framework by using clar
assertions where necessary. Introduce `test_strcmp_offset__empty()` to
verify `check_strcmp_offset()` behavior when both input strings are
empty. This ensures the function correctly handles edge cases and
returns expected values.

Mentored-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Seyi Kuforiji <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Seyi007

Makefile

@@ -1347,6 +1347,7 @@ CLAR_TEST_SUITES += u-mem-pool
 CLAR_TEST_SUITES += u-prio-queue
 CLAR_TEST_SUITES += u-reftable-tree
 CLAR_TEST_SUITES += u-strbuf
+CLAR_TEST_SUITES += u-strcmp-offset
 CLAR_TEST_SUITES += u-strvec
 CLAR_TEST_PROG = $(UNIT_TEST_BIN)/unit-tests$(X)
 CLAR_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(CLAR_TEST_SUITES))
@@ -1364,7 +1365,6 @@ UNIT_TEST_PROGRAMS += t-reftable-reader
 UNIT_TEST_PROGRAMS += t-reftable-readwrite
 UNIT_TEST_PROGRAMS += t-reftable-record
 UNIT_TEST_PROGRAMS += t-reftable-stack
-UNIT_TEST_PROGRAMS += t-strcmp-offset
 UNIT_TEST_PROGRAMS += t-trailer
 UNIT_TEST_PROGRAMS += t-urlmatch-normalization
 UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_BIN)/%$X,$(UNIT_TEST_PROGRAMS))

t/meson.build

@@ -7,6 +7,7 @@ clar_test_suites = [
   'unit-tests/u-prio-queue.c',
   'unit-tests/u-reftable-tree.c',
   'unit-tests/u-strbuf.c',
+  'unit-tests/u-strcmp-offset.c',
   'unit-tests/u-strvec.c',
 ]
 
@@ -58,7 +59,6 @@ unit_test_programs = [
   'unit-tests/t-reftable-readwrite.c',
   'unit-tests/t-reftable-record.c',
   'unit-tests/t-reftable-stack.c',
-  'unit-tests/t-strcmp-offset.c',
   'unit-tests/t-trailer.c',
   'unit-tests/t-urlmatch-normalization.c',
 ]

t/unit-tests/t-strcmp-offset.c

@@ -0,0 +1,45 @@
+#include "unit-test.h"
+#include "read-cache-ll.h"
+
+static void check_strcmp_offset(const char *string1, const char *string2,
+				int expect_result, uintmax_t expect_offset)
+{
+	size_t offset;
+	int result = strcmp_offset(string1, string2, &offset);
+
+	/*
+	 * Because different CRTs behave differently, only rely on signs of the
+	 * result values.
+	 */
+	result = (result < 0 ? -1 :
+			result > 0 ? 1 :
+			0);
+
+	cl_assert_equal_i(result, expect_result);
+	cl_assert_equal_i((uintmax_t)offset, expect_offset);
+}
+
+void test_strcmp_offset__empty(void)
+{
+	check_strcmp_offset("", "", 0, 0);
+}
+
+void test_strcmp_offset__equal(void)
+{
+	check_strcmp_offset("abc", "abc", 0, 3);
+}
+
+void test_strcmp_offset__different(void)
+{
+	check_strcmp_offset("abc", "def", -1, 0);
+}
+
+void test_strcmp_offset__mismatch(void)
+{
+	check_strcmp_offset("abc", "abz", -1, 2);
+}
+
+void test_strcmp_offset__different_length(void)
+{
+	check_strcmp_offset("abc", "abcdef", -1, 3);
+}