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- // SPDX-License-Identifier: GPL-2.0
- /*
- * KUnit test for the linear_ranges helper.
- *
- * Copyright (C) 2020, ROHM Semiconductors.
- * Author: Matti Vaittinen <[email protected]>
- */
- #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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