// 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[] = {
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");
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