leds: led-test: Provide tests for the lookup and get infrastructure

This API allows providers to offer an specific LED to be looked-up by a
consumer.  Consumers are then able to describe the aforementioned LED
and take a reference on it.

For convenience, we're testing both sides of the API in just one test
function here.  In reality, both the provider and the consumer would be
logistically orthogonal.

CMD:
  tools/testing/kunit/kunit.py run --kunitconfig drivers/leds

RESULTS:
  [16:38:57] Configuring KUnit Kernel ...
  [16:38:57] Building KUnit Kernel ...
  Populating config with:
  $ make ARCH=um O=.kunit olddefconfig
  Building with:
  $ make all compile_commands.json scripts_gdb ARCH=um O=.kunit --jobs=20
  [16:39:02] Starting KUnit Kernel (1/1)...
  [16:39:02] ============================================================
  Running tests with:
  $ .kunit/linux kunit.enable=1 mem=1G console=tty kunit_shutdown=halt
  [16:39:03] ===================== led (2 subtests) =====================
  [16:39:03] [PASSED] led_test_class_register
  [16:39:03] [PASSED] led_test_class_add_lookup_and_get
  [16:39:03] ======================= [PASSED] led =======================
  [16:39:03] ============================================================
  [16:39:03] Testing complete. Ran 2 tests: passed: 2
  [16:39:03] Elapsed time: 6.255s total, 0.001s configuring, 5.131s building, 1.106s running

Link: https://lore.kernel.org/r/20250501081918.3621432-3-lee@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: lag-linaro

drivers/leds/led-test.c

@@ -57,8 +57,37 @@ static void led_test_class_register(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ret, -EEXIST);
 }
 
+static void led_test_class_add_lookup_and_get(struct kunit *test)
+{
+	struct led_test_ddata *ddata = test->priv;
+	struct led_classdev *cdev = &ddata->cdev, *cdev_get;
+	struct device *dev = ddata->dev;
+	struct led_lookup_data lookup;
+	int ret;
+
+	/* First, register a LED class device */
+	cdev->name = "led-test";
+	ret = devm_led_classdev_register(dev, cdev);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	/* Then make the LED available for lookup */
+	lookup.provider = cdev->name;
+	lookup.dev_id = dev_name(dev);
+	lookup.con_id = "led-test-1";
+	led_add_lookup(&lookup);
+
+	/* Finally, attempt to look it up via the API - imagine this was an orthogonal driver */
+	cdev_get = devm_led_get(dev, "led-test-1");
+	KUNIT_ASSERT_FALSE(test, IS_ERR(cdev_get));
+
+	KUNIT_EXPECT_STREQ(test, cdev_get->name, cdev->name);
+
+	led_remove_lookup(&lookup);
+}
+
 static struct kunit_case led_test_cases[] = {
 	KUNIT_CASE(led_test_class_register),
+	KUNIT_CASE(led_test_class_add_lookup_and_get),
 	{ }
 };