1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KUnit test for the linear_ranges helper.
4 *
5 * Copyright (C) 2020, ROHM Semiconductors.
6 * Author: Matti Vaittinen <matti.vaittien@fi.rohmeurope.com>
7 */
8 #include <kunit/test.h>
9
10 #include <linux/linear_range.h>
11
12 /* First things first. I deeply dislike unit-tests. I have seen all the hell
13 * breaking loose when people who think the unit tests are "the silver bullet"
14 * to kill bugs get to decide how a company should implement testing strategy...
15 *
16 * Believe me, it may get _really_ ridiculous. It is tempting to think that
17 * walking through all the possible execution branches will nail down 100% of
18 * bugs. This may lead to ideas about demands to get certain % of "test
19 * coverage" - measured as line coverage. And that is one of the worst things
20 * you can do.
21 *
22 * Ask people to provide line coverage and they do. I've seen clever tools
23 * which generate test cases to test the existing functions - and by default
24 * these tools expect code to be correct and just generate checks which are
25 * passing when ran against current code-base. Run this generator and you'll get
26 * tests that do not test code is correct but just verify nothing changes.
27 * Problem is that testing working code is pointless. And if it is not
28 * working, your test must not assume it is working. You won't catch any bugs
29 * by such tests. What you can do is to generate a huge amount of tests.
30 * Especially if you were are asked to proivde 100% line-coverage x_x. So what
31 * does these tests - which are not finding any bugs now - do?
32 *
33 * They add inertia to every future development. I think it was Terry Pratchet
34 * who wrote someone having same impact as thick syrup has to chronometre.
35 * Excessive amount of unit-tests have this effect to development. If you do
36 * actually find _any_ bug from code in such environment and try fixing it...
37 * ...chances are you also need to fix the test cases. In sunny day you fix one
38 * test. But I've done refactoring which resulted 500+ broken tests (which had
39 * really zero value other than proving to managers that we do do "quality")...
40 *
41 * After this being said - there are situations where UTs can be handy. If you
42 * have algorithms which take some input and should produce output - then you
43 * can implement few, carefully selected simple UT-cases which test this. I've
44 * previously used this for example for netlink and device-tree data parsing
45 * functions. Feed some data examples to functions and verify the output is as
46 * expected. I am not covering all the cases but I will see the logic should be
47 * working.
48 *
49 * Here we also do some minor testing. I don't want to go through all branches
50 * or test more or less obvious things - but I want to see the main logic is
51 * working. And I definitely don't want to add 500+ test cases that break when
52 * some simple fix is done x_x. So - let's only add few, well selected tests
53 * which ensure as much logic is good as possible.
54 */
55
56 /*
57 * Test Range 1:
58 * selectors: 2 3 4 5 6
59 * values (5): 10 20 30 40 50
60 *
61 * Test Range 2:
62 * selectors: 7 8 9 10
63 * values (4): 100 150 200 250
64 */
65
66 #define RANGE1_MIN 10
67 #define RANGE1_MIN_SEL 2
68 #define RANGE1_STEP 10
69
70 /* 2, 3, 4, 5, 6 */
71 static const unsigned int range1_sels[] = { RANGE1_MIN_SEL, RANGE1_MIN_SEL + 1,
72 RANGE1_MIN_SEL + 2,
73 RANGE1_MIN_SEL + 3,
74 RANGE1_MIN_SEL + 4 };
75 /* 10, 20, 30, 40, 50 */
76 static const unsigned int range1_vals[] = { RANGE1_MIN, RANGE1_MIN +
77 RANGE1_STEP,
78 RANGE1_MIN + RANGE1_STEP * 2,
79 RANGE1_MIN + RANGE1_STEP * 3,
80 RANGE1_MIN + RANGE1_STEP * 4 };
81
82 #define RANGE2_MIN 100
83 #define RANGE2_MIN_SEL 7
84 #define RANGE2_STEP 50
85
86 /* 7, 8, 9, 10 */
87 static const unsigned int range2_sels[] = { RANGE2_MIN_SEL, RANGE2_MIN_SEL + 1,
88 RANGE2_MIN_SEL + 2,
89 RANGE2_MIN_SEL + 3 };
90 /* 100, 150, 200, 250 */
91 static const unsigned int range2_vals[] = { RANGE2_MIN, RANGE2_MIN +
92 RANGE2_STEP,
93 RANGE2_MIN + RANGE2_STEP * 2,
94 RANGE2_MIN + RANGE2_STEP * 3 };
95
96 #define RANGE1_NUM_VALS (ARRAY_SIZE(range1_vals))
97 #define RANGE2_NUM_VALS (ARRAY_SIZE(range2_vals))
98 #define RANGE_NUM_VALS (RANGE1_NUM_VALS + RANGE2_NUM_VALS)
99
100 #define RANGE1_MAX_SEL (RANGE1_MIN_SEL + RANGE1_NUM_VALS - 1)
101 #define RANGE1_MAX_VAL (range1_vals[RANGE1_NUM_VALS - 1])
102
103 #define RANGE2_MAX_SEL (RANGE2_MIN_SEL + RANGE2_NUM_VALS - 1)
104 #define RANGE2_MAX_VAL (range2_vals[RANGE2_NUM_VALS - 1])
105
106 #define SMALLEST_SEL RANGE1_MIN_SEL
107 #define SMALLEST_VAL RANGE1_MIN
108
109 static struct linear_range testr[] = {
110 LINEAR_RANGE(RANGE1_MIN, RANGE1_MIN_SEL, RANGE1_MAX_SEL, RANGE1_STEP),
111 LINEAR_RANGE(RANGE2_MIN, RANGE2_MIN_SEL, RANGE2_MAX_SEL, RANGE2_STEP),
112 };
113
range_test_get_value(struct kunit * test)114 static void range_test_get_value(struct kunit *test)
115 {
116 int ret, i;
117 unsigned int sel, val;
118
119 for (i = 0; i < RANGE1_NUM_VALS; i++) {
120 sel = range1_sels[i];
121 ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
122 KUNIT_EXPECT_EQ(test, 0, ret);
123 KUNIT_EXPECT_EQ(test, val, range1_vals[i]);
124 }
125 for (i = 0; i < RANGE2_NUM_VALS; i++) {
126 sel = range2_sels[i];
127 ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
128 KUNIT_EXPECT_EQ(test, 0, ret);
129 KUNIT_EXPECT_EQ(test, val, range2_vals[i]);
130 }
131 ret = linear_range_get_value_array(&testr[0], 2, sel + 1, &val);
132 KUNIT_EXPECT_NE(test, 0, ret);
133 }
134
range_test_get_selector_high(struct kunit * test)135 static void range_test_get_selector_high(struct kunit *test)
136 {
137 int ret, i;
138 unsigned int sel;
139 bool found;
140
141 for (i = 0; i < RANGE1_NUM_VALS; i++) {
142 ret = linear_range_get_selector_high(&testr[0], range1_vals[i],
143 &sel, &found);
144 KUNIT_EXPECT_EQ(test, 0, ret);
145 KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
146 KUNIT_EXPECT_TRUE(test, found);
147 }
148
149 ret = linear_range_get_selector_high(&testr[0], RANGE1_MAX_VAL + 1,
150 &sel, &found);
151 KUNIT_EXPECT_LE(test, ret, 0);
152
153 ret = linear_range_get_selector_high(&testr[0], RANGE1_MIN - 1,
154 &sel, &found);
155 KUNIT_EXPECT_EQ(test, 0, ret);
156 KUNIT_EXPECT_FALSE(test, found);
157 KUNIT_EXPECT_EQ(test, sel, range1_sels[0]);
158 }
159
range_test_get_value_amount(struct kunit * test)160 static void range_test_get_value_amount(struct kunit *test)
161 {
162 int ret;
163
164 ret = linear_range_values_in_range_array(&testr[0], 2);
165 KUNIT_EXPECT_EQ(test, (int)RANGE_NUM_VALS, ret);
166 }
167
range_test_get_selector_low(struct kunit * test)168 static void range_test_get_selector_low(struct kunit *test)
169 {
170 int i, ret;
171 unsigned int sel;
172 bool found;
173
174 for (i = 0; i < RANGE1_NUM_VALS; i++) {
175 ret = linear_range_get_selector_low_array(&testr[0], 2,
176 range1_vals[i], &sel,
177 &found);
178 KUNIT_EXPECT_EQ(test, 0, ret);
179 KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
180 KUNIT_EXPECT_TRUE(test, found);
181 }
182 for (i = 0; i < RANGE2_NUM_VALS; i++) {
183 ret = linear_range_get_selector_low_array(&testr[0], 2,
184 range2_vals[i], &sel,
185 &found);
186 KUNIT_EXPECT_EQ(test, 0, ret);
187 KUNIT_EXPECT_EQ(test, sel, range2_sels[i]);
188 KUNIT_EXPECT_TRUE(test, found);
189 }
190
191 /*
192 * Seek value greater than range max => get_selector_*_low should
193 * return Ok - but set found to false as value is not in range
194 */
195 ret = linear_range_get_selector_low_array(&testr[0], 2,
196 range2_vals[RANGE2_NUM_VALS - 1] + 1,
197 &sel, &found);
198
199 KUNIT_EXPECT_EQ(test, 0, ret);
200 KUNIT_EXPECT_EQ(test, sel, range2_sels[RANGE2_NUM_VALS - 1]);
201 KUNIT_EXPECT_FALSE(test, found);
202 }
203
204 static struct kunit_case range_test_cases[] = {
205 KUNIT_CASE(range_test_get_value_amount),
206 KUNIT_CASE(range_test_get_selector_high),
207 KUNIT_CASE(range_test_get_selector_low),
208 KUNIT_CASE(range_test_get_value),
209 {},
210 };
211
212 static struct kunit_suite range_test_module = {
213 .name = "linear-ranges-test",
214 .test_cases = range_test_cases,
215 };
216
217 kunit_test_suites(&range_test_module);
218
219 MODULE_DESCRIPTION("KUnit test for the linear_ranges helper");
220 MODULE_LICENSE("GPL");
221