[PATCH v4] lib/math: Add int_pow test suite

[Luis Felipe Hernandez <luis.hernandez093@gmail.com>]

Adds test suite for integer based power function.

Signed-off-by: Luis Felipe Hernandez <luis.hernandez093@gmail.com>
---
Changes in v4:
  - Address checkpatch warning and make kconfig description longer
  - Use GPL-2.0-only for consistency
  - Spelling fix fith -> fifth
Changes in v3:
  - Fix compiler warning: explicitly define constant as unsigned int
  - Add changes in patch revisions
Changes in v2:
  - Address review feedback
  - Add kconfig entry
  - Use correct dir and file convention for KUnit
  - Fix typo
  - Remove unused static_stub header
  - Refactor test suite to use paramerterized test cases
  - Add close to max allowable value to in large_result test case
  - Add test case with non-power of two exponent
  - Fix module license 
---
 lib/Kconfig.debug              |  9 ++++++
 lib/math/Makefile              |  1 +
 lib/math/tests/Makefile        |  3 ++
 lib/math/tests/int_pow_kunit.c | 52 ++++++++++++++++++++++++++++++++++
 4 files changed, 65 insertions(+)
 create mode 100644 lib/math/tests/Makefile
 create mode 100644 lib/math/tests/int_pow_kunit.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a30c03a66172..0f98f73d4322 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -3051,3 +3051,12 @@ config RUST_KERNEL_DOCTESTS
 endmenu # "Rust"
 
 endmenu # Kernel hacking
+
+config INT_POW_TEST
+       tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
+       depends on KUNIT
+       default KUNIT_ALL_TESTS
+       help
+         This option enables the KUnit test suite for the int_pow function,
+         which performs integer exponentiation. The test suite is designed to
+         verify that the implementation of int_pow correctly computes the power
+         of a given base raised to a given exponent.
+
+         Enabling this option will include tests that check various scenarios
+         and edge cases to ensure the accuracy and reliability of the exponentiation
+         function.
+
+         If unsure, say N
diff --git a/lib/math/Makefile b/lib/math/Makefile
index 91fcdb0c9efe..3c1f92a7459d 100644
--- a/lib/math/Makefile
+++ b/lib/math/Makefile
@@ -5,5 +5,6 @@ obj-$(CONFIG_CORDIC)		+= cordic.o
 obj-$(CONFIG_PRIME_NUMBERS)	+= prime_numbers.o
 obj-$(CONFIG_RATIONAL)		+= rational.o
 
+obj-$(CONFIG_INT_POW_TEST)  += tests/int_pow_kunit.o
 obj-$(CONFIG_TEST_DIV64)	+= test_div64.o
 obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational-test.o
diff --git a/lib/math/tests/Makefile b/lib/math/tests/Makefile
new file mode 100644
index 000000000000..6a169123320a
--- /dev/null
+++ b/lib/math/tests/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_INT_POW_TEST) += int_pow_kunit.o
diff --git a/lib/math/tests/int_pow_kunit.c b/lib/math/tests/int_pow_kunit.c
new file mode 100644
index 000000000000..7b6a5ae70eb4
--- /dev/null
+++ b/lib/math/tests/int_pow_kunit.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+#include <linux/math.h>
+
+struct test_case_params {
+	u64 base;
+	unsigned int exponent;
+	u64 expected_result;
+	const char *name;
+};
+
+static const struct test_case_params params[] = {
+	{ 64, 0, 1, "Power of zero" },
+	{ 64, 1, 64, "Power of one"},
+	{ 0, 5, 0, "Base zero" },
+	{ 1, 64, 1, "Base one" },
+	{ 2, 2, 4, "Two squared"},
+	{ 2, 3, 8, "Two cubed"},
+	{ 5, 5, 3125, "Five raised to the fifth power" },
+	{ U64_MAX, 1, U64_MAX, "Max base" },
+	{ 2, 63, 9223372036854775808, "Large result"},
+};
+
+static void get_desc(const struct test_case_params *tc, char *desc)
+{
+	strscpy(desc, tc->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+KUNIT_ARRAY_PARAM(int_pow, params, get_desc);
+
+static void int_pow_test(struct kunit *test)
+{
+	const struct test_case_params *tc = (const struct test_case_params *)test->param_value;
+
+	KUNIT_EXPECT_EQ(test, tc->expected_result, int_pow(tc->base, tc->exponent));
+}
+
+static struct kunit_case math_int_pow_test_cases[] = {
+	KUNIT_CASE_PARAM(int_pow_test, int_pow_gen_params),
+	{}
+};
+
+static struct kunit_suite int_pow_test_suite = {
+	.name = "math-int_pow",
+	.test_cases = math_int_pow_test_cases,
+};
+
+kunit_test_suites(&int_pow_test_suite);
+
+MODULE_DESCRIPTION("math.int_pow KUnit test suite");
+MODULE_LICENSE("GPL");
-- 
2.46.0