// 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[] = {	LINEAR_RANGE(RANGE1_MIN, RANGE1_MIN_SEL, RANGE1_MAX_SEL, RANGE1_STEP),	LINEAR_RANGE(RANGE2_MIN, RANGE2_MIN_SEL, RANGE2_MAX_SEL, 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_DESCRIPTION("KUnit test for the linear_ranges helper");MODULE_LICENSE("GPL");