// 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");