lib/test_linear_ranges: add a test for the 'linear_ranges' (33d599f0) · Commits · 戴 / test

lib/Kconfig.debug

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Original line number	Diff line number	Diff line
		@@ -2092,6 +2092,18 @@ config LIST_KUNIT_TEST

		If unsure, say N.

		config LINEAR_RANGES_TEST
		tristate "KUnit test for linear_ranges"
		depends on KUNIT
		select LINEAR_RANGES
		help
		This builds the linear_ranges unit test, which runs on boot.
		Tests the linear_ranges logic correctness.
		For more information on KUnit and unit tests in general please refer
		to the KUnit documentation in Documentation/dev-tools/kunit/.

		If unsure, say N.

		config TEST_UDELAY
		tristate "udelay test driver"
		help

lib/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -310,3 +310,4 @@ obj-$(CONFIG_OBJAGG) += objagg.o

		# KUnit tests
		obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
		obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o

lib/test_linear_ranges.c

0 → 100644

+228 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/*
		* KUnit test for the linear_ranges helper.
		*
		* Copyright (C) 2020, ROHM Semiconductors.
		* Author: Matti Vaittinen <matti.vaittien@fi.rohmeurope.com>
		*/
		#include <kunit/test.h>

		#include <linux/linear_range.h>

		/* First things first. I deeply dislike unit-tests. I have seen all the hell
		* breaking loose when people who think the unit tests are "the silver bullet"
		* to kill bugs get to decide how a company should implement testing strategy...
		*
		* Believe me, it may get _really_ ridiculous. It is tempting to think that
		* walking through all the possible execution branches will nail down 100% of
		* bugs. This may lead to ideas about demands to get certain % of "test
		* coverage" - measured as line coverage. And that is one of the worst things
		* you can do.
		*
		* Ask people to provide line coverage and they do. I've seen clever tools
		* which generate test cases to test the existing functions - and by default
		* these tools expect code to be correct and just generate checks which are
		* passing when ran against current code-base. Run this generator and you'll get
		* tests that do not test code is correct but just verify nothing changes.
		* Problem is that testing working code is pointless. And if it is not
		* working, your test must not assume it is working. You won't catch any bugs
		* by such tests. What you can do is to generate a huge amount of tests.
		* Especially if you were are asked to proivde 100% line-coverage x_x. So what
		* does these tests - which are not finding any bugs now - do?
		*
		* They add inertia to every future development. I think it was Terry Pratchet
		* who wrote someone having same impact as thick syrup has to chronometre.
		* Excessive amount of unit-tests have this effect to development. If you do
		* actually find _any_ bug from code in such environment and try fixing it...
		* ...chances are you also need to fix the test cases. In sunny day you fix one
		* test. But I've done refactoring which resulted 500+ broken tests (which had
		* really zero value other than proving to managers that we do do "quality")...
		*
		* After this being said - there are situations where UTs can be handy. If you
		* have algorithms which take some input and should produce output - then you
		* can implement few, carefully selected simple UT-cases which test this. I've
		* previously used this for example for netlink and device-tree data parsing
		* functions. Feed some data examples to functions and verify the output is as
		* expected. I am not covering all the cases but I will see the logic should be
		* working.
		*
		* Here we also do some minor testing. I don't want to go through all branches
		* or test more or less obvious things - but I want to see the main logic is
		* working. And I definitely don't want to add 500+ test cases that break when
		* some simple fix is done x_x. So - let's only add few, well selected tests
		* which ensure as much logic is good as possible.
		*/

		/*
		* Test Range 1:
		* selectors: 2 3 4 5 6
		* values (5): 10 20 30 40 50
		*
		* Test Range 2:
		* selectors: 7 8 9 10
		* values (4): 100 150 200 250
		*/

		#define RANGE1_MIN 10
		#define RANGE1_MIN_SEL 2
		#define RANGE1_STEP 10

		/* 2, 3, 4, 5, 6 */
		static const unsigned int range1_sels[] = { RANGE1_MIN_SEL, RANGE1_MIN_SEL + 1,
		RANGE1_MIN_SEL + 2,
		RANGE1_MIN_SEL + 3,
		RANGE1_MIN_SEL + 4 };
		/* 10, 20, 30, 40, 50 */
		static const unsigned int range1_vals[] = { RANGE1_MIN, RANGE1_MIN +
		RANGE1_STEP,
		RANGE1_MIN + RANGE1_STEP * 2,
		RANGE1_MIN + RANGE1_STEP * 3,
		RANGE1_MIN + RANGE1_STEP * 4 };

		#define RANGE2_MIN 100
		#define RANGE2_MIN_SEL 7
		#define RANGE2_STEP 50

		/* 7, 8, 9, 10 */
		static const unsigned int range2_sels[] = { RANGE2_MIN_SEL, RANGE2_MIN_SEL + 1,
		RANGE2_MIN_SEL + 2,
		RANGE2_MIN_SEL + 3 };
		/* 100, 150, 200, 250 */
		static const unsigned int range2_vals[] = { RANGE2_MIN, RANGE2_MIN +
		RANGE2_STEP,
		RANGE2_MIN + RANGE2_STEP * 2,
		RANGE2_MIN + RANGE2_STEP * 3 };

		#define RANGE1_NUM_VALS (ARRAY_SIZE(range1_vals))
		#define RANGE2_NUM_VALS (ARRAY_SIZE(range2_vals))
		#define RANGE_NUM_VALS (RANGE1_NUM_VALS + RANGE2_NUM_VALS)

		#define RANGE1_MAX_SEL (RANGE1_MIN_SEL + RANGE1_NUM_VALS - 1)
		#define RANGE1_MAX_VAL (range1_vals[RANGE1_NUM_VALS - 1])

		#define RANGE2_MAX_SEL (RANGE2_MIN_SEL + RANGE2_NUM_VALS - 1)
		#define RANGE2_MAX_VAL (range2_vals[RANGE2_NUM_VALS - 1])

		#define SMALLEST_SEL RANGE1_MIN_SEL
		#define SMALLEST_VAL RANGE1_MIN

		static struct linear_range testr[] = {
		{
		.min = RANGE1_MIN,
		.min_sel = RANGE1_MIN_SEL,
		.max_sel = RANGE1_MAX_SEL,
		.step = RANGE1_STEP,
		}, {
		.min = RANGE2_MIN,
		.min_sel = RANGE2_MIN_SEL,
		.max_sel = RANGE2_MAX_SEL,
		.step = RANGE2_STEP
		},
		};

		static void range_test_get_value(struct kunit *test)
		{
		int ret, i;
		unsigned int sel, val;

		for (i = 0; i < RANGE1_NUM_VALS; i++) {
		sel = range1_sels[i];
		ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, val, range1_vals[i]);
		}
		for (i = 0; i < RANGE2_NUM_VALS; i++) {
		sel = range2_sels[i];
		ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, val, range2_vals[i]);
		}
		ret = linear_range_get_value_array(&testr[0], 2, sel + 1, &val);
		KUNIT_EXPECT_NE(test, 0, ret);
		}

		static void range_test_get_selector_high(struct kunit *test)
		{
		int ret, i;
		unsigned int sel;
		bool found;

		for (i = 0; i < RANGE1_NUM_VALS; i++) {
		ret = linear_range_get_selector_high(&testr[0], range1_vals[i],
		&sel, &found);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
		KUNIT_EXPECT_TRUE(test, found);
		}

		ret = linear_range_get_selector_high(&testr[0], RANGE1_MAX_VAL + 1,
		&sel, &found);
		KUNIT_EXPECT_LE(test, ret, 0);

		ret = linear_range_get_selector_high(&testr[0], RANGE1_MIN - 1,
		&sel, &found);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_FALSE(test, found);
		KUNIT_EXPECT_EQ(test, sel, range1_sels[0]);
		}

		static void range_test_get_value_amount(struct kunit *test)
		{
		int ret;

		ret = linear_range_values_in_range_array(&testr[0], 2);
		KUNIT_EXPECT_EQ(test, (int)RANGE_NUM_VALS, ret);
		}

		static void range_test_get_selector_low(struct kunit *test)
		{
		int i, ret;
		unsigned int sel;
		bool found;

		for (i = 0; i < RANGE1_NUM_VALS; i++) {
		ret = linear_range_get_selector_low_array(&testr[0], 2,
		range1_vals[i], &sel,
		&found);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
		KUNIT_EXPECT_TRUE(test, found);
		}
		for (i = 0; i < RANGE2_NUM_VALS; i++) {
		ret = linear_range_get_selector_low_array(&testr[0], 2,
		range2_vals[i], &sel,
		&found);
		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, sel, range2_sels[i]);
		KUNIT_EXPECT_TRUE(test, found);
		}

		/*
		* Seek value greater than range max => get_selector_*_low should
		* return Ok - but set found to false as value is not in range
		*/
		ret = linear_range_get_selector_low_array(&testr[0], 2,
		range2_vals[RANGE2_NUM_VALS - 1] + 1,
		&sel, &found);

		KUNIT_EXPECT_EQ(test, 0, ret);
		KUNIT_EXPECT_EQ(test, sel, range2_sels[RANGE2_NUM_VALS - 1]);
		KUNIT_EXPECT_FALSE(test, found);
		}

		static struct kunit_case range_test_cases[] = {
		KUNIT_CASE(range_test_get_value_amount),
		KUNIT_CASE(range_test_get_selector_high),
		KUNIT_CASE(range_test_get_selector_low),
		KUNIT_CASE(range_test_get_value),
		{},
		};

		static struct kunit_suite range_test_module = {
		.name = "linear-ranges-test",
		.test_cases = range_test_cases,
		};

		kunit_test_suites(&range_test_module);

		MODULE_LICENSE("GPL");

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