lib: math: Move KUnit tests into tests/ subdir

This patch is a follow-up task from a discussion stemming from point 3
in a recent patch introducing the int_pow kunit test [1] and
documentation regarding kunit test style and nomenclature [2].

Colocate all kunit test suites in lib/math/tests/ and
follow recommended naming convention for files <suite>_kunit.c
and kconfig entries CONFIG_<name>_KUNIT_TEST.

Link: https://lore.kernel.org/all/CABVgOS=-vh5TqHFCq_jo=ffq8v_nGgr6JsPnOZag3e6+19ysxQ@mail.gmail.com/ [1]
Link: https://docs.kernel.org/dev-tools/kunit/style.html [2]

Signed-off-by: Luis Felipe Hernandez <luis.hernandez093@gmail.com>
Acked-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Link: https://lore.kernel.org/r/20241202075545.3648096-2-davidgow@google.com
Signed-off-by: Kees Cook <kees@kernel.org>

2 files changed, 60 insertions, 2 deletions

diff --git a/lib/math/tests/Makefile b/lib/math/tests/Makefile
index e1a79f093b2d..a982f71800bd 100644
--- a/lib/math/tests/Makefile
+++ b/lib/math/tests/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-obj-$(CONFIG_INT_POW_TEST) += int_pow_kunit.o
-obj-$(CONFIG_INT_SQRT_KUNIT_TEST) += int_sqrt_kunit.o
+obj-$(CONFIG_INT_POW_KUNIT_TEST)	+= int_pow_kunit.o
+obj-$(CONFIG_INT_SQRT_KUNIT_TEST)	+= int_sqrt_kunit.o
+obj-$(CONFIG_RATIONAL_KUNIT_TEST)	+= rational_kunit.o
diff --git a/lib/math/tests/rational_kunit.c b/lib/math/tests/rational_kunit.c
new file mode 100644
index 000000000000..47486a95f088
--- /dev/null
+++ b/lib/math/tests/rational_kunit.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <kunit/test.h>
+
+#include <linux/rational.h>
+
+struct rational_test_param {
+	unsigned long num, den;
+	unsigned long max_num, max_den;
+	unsigned long exp_num, exp_den;
+
+	const char *name;
+};
+
+static const struct rational_test_param test_parameters[] = {
+	{ 1230,	10,	100, 20,	100, 1,    "Exceeds bounds, semi-convergent term > 1/2 last term" },
+	{ 34567,100, 	120, 20,	120, 1,    "Exceeds bounds, semi-convergent term < 1/2 last term" },
+	{ 1, 30,	100, 10,	0, 1,	   "Closest to zero" },
+	{ 1, 19,	100, 10,	1, 10,     "Closest to smallest non-zero" },
+	{ 27,32,	16, 16,		11, 13,    "Use convergent" },
+	{ 1155, 7735,	255, 255,	33, 221,   "Exact answer" },
+	{ 87, 32,	70, 32,		68, 25,    "Semiconvergent, numerator limit" },
+	{ 14533, 4626,	15000, 2400,	7433, 2366, "Semiconvergent, denominator limit" },
+};
+
+static void get_desc(const struct rational_test_param *param, char *desc)
+{
+	strscpy(desc, param->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+/* Creates function rational_gen_params */
+KUNIT_ARRAY_PARAM(rational, test_parameters, get_desc);
+
+static void rational_test(struct kunit *test)
+{
+	const struct rational_test_param *param = (const struct rational_test_param *)test->param_value;
+	unsigned long n = 0, d = 0;
+
+	rational_best_approximation(param->num, param->den, param->max_num, param->max_den, &n, &d);
+	KUNIT_EXPECT_EQ(test, n, param->exp_num);
+	KUNIT_EXPECT_EQ(test, d, param->exp_den);
+}
+
+static struct kunit_case rational_test_cases[] = {
+	KUNIT_CASE_PARAM(rational_test, rational_gen_params),
+	{}
+};
+
+static struct kunit_suite rational_test_suite = {
+	.name = "rational",
+	.test_cases = rational_test_cases,
+};
+
+kunit_test_suites(&rational_test_suite);
+
+MODULE_DESCRIPTION("Rational fractions unit test");
+MODULE_LICENSE("GPL v2");