1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 Writing Tests 3 Writing Tests
4 ============= 4 =============
5 5
6 Test Cases 6 Test Cases
7 ---------- 7 ----------
8 8
9 The fundamental unit in KUnit is the test case 9 The fundamental unit in KUnit is the test case. A test case is a function with
10 the signature ``void (*)(struct kunit *test)`` 10 the signature ``void (*)(struct kunit *test)``. It calls the function under test
11 and then sets *expectations* for what should h 11 and then sets *expectations* for what should happen. For example:
12 12
13 .. code-block:: c 13 .. code-block:: c
14 14
15 void example_test_success(struct kunit 15 void example_test_success(struct kunit *test)
16 { 16 {
17 } 17 }
18 18
19 void example_test_failure(struct kunit 19 void example_test_failure(struct kunit *test)
20 { 20 {
21 KUNIT_FAIL(test, "This test ne 21 KUNIT_FAIL(test, "This test never passes.");
22 } 22 }
23 23
24 In the above example, ``example_test_success`` 24 In the above example, ``example_test_success`` always passes because it does
25 nothing; no expectations are set, and therefor 25 nothing; no expectations are set, and therefore all expectations pass. On the
26 other hand ``example_test_failure`` always fai 26 other hand ``example_test_failure`` always fails because it calls ``KUNIT_FAIL``,
27 which is a special expectation that logs a mes 27 which is a special expectation that logs a message and causes the test case to
28 fail. 28 fail.
29 29
30 Expectations 30 Expectations
31 ~~~~~~~~~~~~ 31 ~~~~~~~~~~~~
32 An *expectation* specifies that we expect a pi 32 An *expectation* specifies that we expect a piece of code to do something in a
33 test. An expectation is called like a function 33 test. An expectation is called like a function. A test is made by setting
34 expectations about the behavior of a piece of 34 expectations about the behavior of a piece of code under test. When one or more
35 expectations fail, the test case fails and inf 35 expectations fail, the test case fails and information about the failure is
36 logged. For example: 36 logged. For example:
37 37
38 .. code-block:: c 38 .. code-block:: c
39 39
40 void add_test_basic(struct kunit *test 40 void add_test_basic(struct kunit *test)
41 { 41 {
42 KUNIT_EXPECT_EQ(test, 1, add(1 42 KUNIT_EXPECT_EQ(test, 1, add(1, 0));
43 KUNIT_EXPECT_EQ(test, 2, add(1 43 KUNIT_EXPECT_EQ(test, 2, add(1, 1));
44 } 44 }
45 45
46 In the above example, ``add_test_basic`` makes 46 In the above example, ``add_test_basic`` makes a number of assertions about the
47 behavior of a function called ``add``. The fir 47 behavior of a function called ``add``. The first parameter is always of type
48 ``struct kunit *``, which contains information 48 ``struct kunit *``, which contains information about the current test context.
49 The second parameter, in this case, is what th 49 The second parameter, in this case, is what the value is expected to be. The
50 last value is what the value actually is. If ` 50 last value is what the value actually is. If ``add`` passes all of these
51 expectations, the test case, ``add_test_basic` 51 expectations, the test case, ``add_test_basic`` will pass; if any one of these
52 expectations fails, the test case will fail. 52 expectations fails, the test case will fail.
53 53
54 A test case *fails* when any expectation is vi 54 A test case *fails* when any expectation is violated; however, the test will
55 continue to run, and try other expectations un 55 continue to run, and try other expectations until the test case ends or is
56 otherwise terminated. This is as opposed to *a 56 otherwise terminated. This is as opposed to *assertions* which are discussed
57 later. 57 later.
58 58
59 To learn about more KUnit expectations, see Do 59 To learn about more KUnit expectations, see Documentation/dev-tools/kunit/api/test.rst.
60 60
61 .. note:: 61 .. note::
62 A single test case should be short, easy to 62 A single test case should be short, easy to understand, and focused on a
63 single behavior. 63 single behavior.
64 64
65 For example, if we want to rigorously test the 65 For example, if we want to rigorously test the ``add`` function above, create
66 additional tests cases which would test each p 66 additional tests cases which would test each property that an ``add`` function
67 should have as shown below: 67 should have as shown below:
68 68
69 .. code-block:: c 69 .. code-block:: c
70 70
71 void add_test_basic(struct kunit *test 71 void add_test_basic(struct kunit *test)
72 { 72 {
73 KUNIT_EXPECT_EQ(test, 1, add(1 73 KUNIT_EXPECT_EQ(test, 1, add(1, 0));
74 KUNIT_EXPECT_EQ(test, 2, add(1 74 KUNIT_EXPECT_EQ(test, 2, add(1, 1));
75 } 75 }
76 76
77 void add_test_negative(struct kunit *t 77 void add_test_negative(struct kunit *test)
78 { 78 {
79 KUNIT_EXPECT_EQ(test, 0, add(- 79 KUNIT_EXPECT_EQ(test, 0, add(-1, 1));
80 } 80 }
81 81
82 void add_test_max(struct kunit *test) 82 void add_test_max(struct kunit *test)
83 { 83 {
84 KUNIT_EXPECT_EQ(test, INT_MAX, 84 KUNIT_EXPECT_EQ(test, INT_MAX, add(0, INT_MAX));
85 KUNIT_EXPECT_EQ(test, -1, add( 85 KUNIT_EXPECT_EQ(test, -1, add(INT_MAX, INT_MIN));
86 } 86 }
87 87
88 void add_test_overflow(struct kunit *t 88 void add_test_overflow(struct kunit *test)
89 { 89 {
90 KUNIT_EXPECT_EQ(test, INT_MIN, 90 KUNIT_EXPECT_EQ(test, INT_MIN, add(INT_MAX, 1));
91 } 91 }
92 92
93 Assertions 93 Assertions
94 ~~~~~~~~~~ 94 ~~~~~~~~~~
95 95
96 An assertion is like an expectation, except th 96 An assertion is like an expectation, except that the assertion immediately
97 terminates the test case if the condition is n 97 terminates the test case if the condition is not satisfied. For example:
98 98
99 .. code-block:: c 99 .. code-block:: c
100 100
101 static void test_sort(struct kunit *te 101 static void test_sort(struct kunit *test)
102 { 102 {
103 int *a, i, r = 1; 103 int *a, i, r = 1;
104 a = kunit_kmalloc_array(test, 104 a = kunit_kmalloc_array(test, TEST_LEN, sizeof(*a), GFP_KERNEL);
105 KUNIT_ASSERT_NOT_ERR_OR_NULL(t 105 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a);
106 for (i = 0; i < TEST_LEN; i++) 106 for (i = 0; i < TEST_LEN; i++) {
107 r = (r * 725861) % 659 107 r = (r * 725861) % 6599;
108 a[i] = r; 108 a[i] = r;
109 } 109 }
110 sort(a, TEST_LEN, sizeof(*a), 110 sort(a, TEST_LEN, sizeof(*a), cmpint, NULL);
111 for (i = 0; i < TEST_LEN-1; i+ 111 for (i = 0; i < TEST_LEN-1; i++)
112 KUNIT_EXPECT_LE(test, 112 KUNIT_EXPECT_LE(test, a[i], a[i + 1]);
113 } 113 }
114 114
115 In this example, we need to be able to allocat 115 In this example, we need to be able to allocate an array to test the ``sort()``
116 function. So we use ``KUNIT_ASSERT_NOT_ERR_OR_ 116 function. So we use ``KUNIT_ASSERT_NOT_ERR_OR_NULL()`` to abort the test if
117 there's an allocation error. 117 there's an allocation error.
118 118
119 .. note:: 119 .. note::
120 In other test frameworks, ``ASSERT`` macros 120 In other test frameworks, ``ASSERT`` macros are often implemented by calling
121 ``return`` so they only work from the test 121 ``return`` so they only work from the test function. In KUnit, we stop the
122 current kthread on failure, so you can call 122 current kthread on failure, so you can call them from anywhere.
123 123
124 .. note:: <<
125 Warning: There is an exception to the above <<
126 in the suite's exit() function, or in the f <<
127 run when a test is shutting down, and an as <<
128 cleanup code from running, potentially lead <<
129 <<
130 Customizing error messages 124 Customizing error messages
131 -------------------------- 125 --------------------------
132 126
133 Each of the ``KUNIT_EXPECT`` and ``KUNIT_ASSER 127 Each of the ``KUNIT_EXPECT`` and ``KUNIT_ASSERT`` macros have a ``_MSG``
134 variant. These take a format string and argum 128 variant. These take a format string and arguments to provide additional
135 context to the automatically generated error m 129 context to the automatically generated error messages.
136 130
137 .. code-block:: c 131 .. code-block:: c
138 132
139 char some_str[41]; 133 char some_str[41];
140 generate_sha1_hex_string(some_str); 134 generate_sha1_hex_string(some_str);
141 135
142 /* Before. Not easy to tell why the te 136 /* Before. Not easy to tell why the test failed. */
143 KUNIT_EXPECT_EQ(test, strlen(some_str) 137 KUNIT_EXPECT_EQ(test, strlen(some_str), 40);
144 138
145 /* After. Now we see the offending str 139 /* After. Now we see the offending string. */
146 KUNIT_EXPECT_EQ_MSG(test, strlen(some_ 140 KUNIT_EXPECT_EQ_MSG(test, strlen(some_str), 40, "some_str='%s'", some_str);
147 141
148 Alternatively, one can take full control over 142 Alternatively, one can take full control over the error message by using
149 ``KUNIT_FAIL()``, e.g. 143 ``KUNIT_FAIL()``, e.g.
150 144
151 .. code-block:: c 145 .. code-block:: c
152 146
153 /* Before */ 147 /* Before */
154 KUNIT_EXPECT_EQ(test, some_setup_funct 148 KUNIT_EXPECT_EQ(test, some_setup_function(), 0);
155 149
156 /* After: full control over the failur 150 /* After: full control over the failure message. */
157 if (some_setup_function()) 151 if (some_setup_function())
158 KUNIT_FAIL(test, "Failed to se 152 KUNIT_FAIL(test, "Failed to setup thing for testing");
159 153
160 154
161 Test Suites 155 Test Suites
162 ~~~~~~~~~~~ 156 ~~~~~~~~~~~
163 157
164 We need many test cases covering all the unit' 158 We need many test cases covering all the unit's behaviors. It is common to have
165 many similar tests. In order to reduce duplica 159 many similar tests. In order to reduce duplication in these closely related
166 tests, most unit testing frameworks (including 160 tests, most unit testing frameworks (including KUnit) provide the concept of a
167 *test suite*. A test suite is a collection of 161 *test suite*. A test suite is a collection of test cases for a unit of code
168 with optional setup and teardown functions tha 162 with optional setup and teardown functions that run before/after the whole
169 suite and/or every test case. !! 163 suite and/or every test case. For example:
170 <<
171 .. note:: <<
172 A test case will only run if it is associat <<
173 <<
174 For example: <<
175 164
176 .. code-block:: c 165 .. code-block:: c
177 166
178 static struct kunit_case example_test_ 167 static struct kunit_case example_test_cases[] = {
179 KUNIT_CASE(example_test_foo), 168 KUNIT_CASE(example_test_foo),
180 KUNIT_CASE(example_test_bar), 169 KUNIT_CASE(example_test_bar),
181 KUNIT_CASE(example_test_baz), 170 KUNIT_CASE(example_test_baz),
182 {} 171 {}
183 }; 172 };
184 173
185 static struct kunit_suite example_test 174 static struct kunit_suite example_test_suite = {
186 .name = "example", 175 .name = "example",
187 .init = example_test_init, 176 .init = example_test_init,
188 .exit = example_test_exit, 177 .exit = example_test_exit,
189 .suite_init = example_suite_in 178 .suite_init = example_suite_init,
190 .suite_exit = example_suite_ex 179 .suite_exit = example_suite_exit,
191 .test_cases = example_test_cas 180 .test_cases = example_test_cases,
192 }; 181 };
193 kunit_test_suite(example_test_suite); 182 kunit_test_suite(example_test_suite);
194 183
195 In the above example, the test suite ``example 184 In the above example, the test suite ``example_test_suite`` would first run
196 ``example_suite_init``, then run the test case 185 ``example_suite_init``, then run the test cases ``example_test_foo``,
197 ``example_test_bar``, and ``example_test_baz`` 186 ``example_test_bar``, and ``example_test_baz``. Each would have
198 ``example_test_init`` called immediately befor 187 ``example_test_init`` called immediately before it and ``example_test_exit``
199 called immediately after it. Finally, ``exampl 188 called immediately after it. Finally, ``example_suite_exit`` would be called
200 after everything else. ``kunit_test_suite(exam 189 after everything else. ``kunit_test_suite(example_test_suite)`` registers the
201 test suite with the KUnit test framework. 190 test suite with the KUnit test framework.
202 191
203 .. note:: 192 .. note::
204 The ``exit`` and ``suite_exit`` functions w !! 193 A test case will only run if it is associated with a test suite.
205 ``suite_init`` fail. Make sure that they ca <<
206 state which may result from ``init`` or ``s <<
207 or exiting early. <<
208 194
209 ``kunit_test_suite(...)`` is a macro which tel 195 ``kunit_test_suite(...)`` is a macro which tells the linker to put the
210 specified test suite in a special linker secti 196 specified test suite in a special linker section so that it can be run by KUnit
211 either after ``late_init``, or when the test m 197 either after ``late_init``, or when the test module is loaded (if the test was
212 built as a module). 198 built as a module).
213 199
214 For more information, see Documentation/dev-to 200 For more information, see Documentation/dev-tools/kunit/api/test.rst.
215 201
216 .. _kunit-on-non-uml: 202 .. _kunit-on-non-uml:
217 203
218 Writing Tests For Other Architectures 204 Writing Tests For Other Architectures
219 ------------------------------------- 205 -------------------------------------
220 206
221 It is better to write tests that run on UML to 207 It is better to write tests that run on UML to tests that only run under a
222 particular architecture. It is better to write 208 particular architecture. It is better to write tests that run under QEMU or
223 another easy to obtain (and monetarily free) s 209 another easy to obtain (and monetarily free) software environment to a specific
224 piece of hardware. 210 piece of hardware.
225 211
226 Nevertheless, there are still valid reasons to 212 Nevertheless, there are still valid reasons to write a test that is architecture
227 or hardware specific. For example, we might wa 213 or hardware specific. For example, we might want to test code that really
228 belongs in ``arch/some-arch/*``. Even so, try 214 belongs in ``arch/some-arch/*``. Even so, try to write the test so that it does
229 not depend on physical hardware. Some of our t 215 not depend on physical hardware. Some of our test cases may not need hardware,
230 only few tests actually require the hardware t 216 only few tests actually require the hardware to test it. When hardware is not
231 available, instead of disabling tests, we can 217 available, instead of disabling tests, we can skip them.
232 218
233 Now that we have narrowed down exactly what bi 219 Now that we have narrowed down exactly what bits are hardware specific, the
234 actual procedure for writing and running the t 220 actual procedure for writing and running the tests is same as writing normal
235 KUnit tests. 221 KUnit tests.
236 222
237 .. important:: 223 .. important::
238 We may have to reset hardware state. If thi 224 We may have to reset hardware state. If this is not possible, we may only
239 be able to run one test case per invocation 225 be able to run one test case per invocation.
240 226
241 .. TODO(brendanhiggins@google.com): Add an act 227 .. TODO(brendanhiggins@google.com): Add an actual example of an architecture-
242 dependent KUnit test. 228 dependent KUnit test.
243 229
244 Common Patterns 230 Common Patterns
245 =============== 231 ===============
246 232
247 Isolating Behavior 233 Isolating Behavior
248 ------------------ 234 ------------------
249 235
250 Unit testing limits the amount of code under t 236 Unit testing limits the amount of code under test to a single unit. It controls
251 what code gets run when the unit under test ca 237 what code gets run when the unit under test calls a function. Where a function
252 is exposed as part of an API such that the def 238 is exposed as part of an API such that the definition of that function can be
253 changed without affecting the rest of the code 239 changed without affecting the rest of the code base. In the kernel, this comes
254 from two constructs: classes, which are struct 240 from two constructs: classes, which are structs that contain function pointers
255 provided by the implementer, and architecture- 241 provided by the implementer, and architecture-specific functions, which have
256 definitions selected at compile time. 242 definitions selected at compile time.
257 243
258 Classes 244 Classes
259 ~~~~~~~ 245 ~~~~~~~
260 246
261 Classes are not a construct that is built into 247 Classes are not a construct that is built into the C programming language;
262 however, it is an easily derived concept. Acco 248 however, it is an easily derived concept. Accordingly, in most cases, every
263 project that does not use a standardized objec 249 project that does not use a standardized object oriented library (like GNOME's
264 GObject) has their own slightly different way 250 GObject) has their own slightly different way of doing object oriented
265 programming; the Linux kernel is no exception. 251 programming; the Linux kernel is no exception.
266 252
267 The central concept in kernel object oriented 253 The central concept in kernel object oriented programming is the class. In the
268 kernel, a *class* is a struct that contains fu 254 kernel, a *class* is a struct that contains function pointers. This creates a
269 contract between *implementers* and *users* si 255 contract between *implementers* and *users* since it forces them to use the
270 same function signature without having to call 256 same function signature without having to call the function directly. To be a
271 class, the function pointers must specify that 257 class, the function pointers must specify that a pointer to the class, known as
272 a *class handle*, be one of the parameters. Th 258 a *class handle*, be one of the parameters. Thus the member functions (also
273 known as *methods*) have access to member vari 259 known as *methods*) have access to member variables (also known as *fields*)
274 allowing the same implementation to have multi 260 allowing the same implementation to have multiple *instances*.
275 261
276 A class can be *overridden* by *child classes* 262 A class can be *overridden* by *child classes* by embedding the *parent class*
277 in the child class. Then when the child class 263 in the child class. Then when the child class *method* is called, the child
278 implementation knows that the pointer passed t 264 implementation knows that the pointer passed to it is of a parent contained
279 within the child. Thus, the child can compute 265 within the child. Thus, the child can compute the pointer to itself because the
280 pointer to the parent is always a fixed offset 266 pointer to the parent is always a fixed offset from the pointer to the child.
281 This offset is the offset of the parent contai 267 This offset is the offset of the parent contained in the child struct. For
282 example: 268 example:
283 269
284 .. code-block:: c 270 .. code-block:: c
285 271
286 struct shape { 272 struct shape {
287 int (*area)(struct shape *this 273 int (*area)(struct shape *this);
288 }; 274 };
289 275
290 struct rectangle { 276 struct rectangle {
291 struct shape parent; 277 struct shape parent;
292 int length; 278 int length;
293 int width; 279 int width;
294 }; 280 };
295 281
296 int rectangle_area(struct shape *this) 282 int rectangle_area(struct shape *this)
297 { 283 {
298 struct rectangle *self = conta 284 struct rectangle *self = container_of(this, struct rectangle, parent);
299 285
300 return self->length * self->wi 286 return self->length * self->width;
301 }; 287 };
302 288
303 void rectangle_new(struct rectangle *s 289 void rectangle_new(struct rectangle *self, int length, int width)
304 { 290 {
305 self->parent.area = rectangle_ 291 self->parent.area = rectangle_area;
306 self->length = length; 292 self->length = length;
307 self->width = width; 293 self->width = width;
308 } 294 }
309 295
310 In this example, computing the pointer to the 296 In this example, computing the pointer to the child from the pointer to the
311 parent is done by ``container_of``. 297 parent is done by ``container_of``.
312 298
313 Faking Classes 299 Faking Classes
314 ~~~~~~~~~~~~~~ 300 ~~~~~~~~~~~~~~
315 301
316 In order to unit test a piece of code that cal 302 In order to unit test a piece of code that calls a method in a class, the
317 behavior of the method must be controllable, o 303 behavior of the method must be controllable, otherwise the test ceases to be a
318 unit test and becomes an integration test. 304 unit test and becomes an integration test.
319 305
320 A fake class implements a piece of code that i 306 A fake class implements a piece of code that is different than what runs in a
321 production instance, but behaves identical fro 307 production instance, but behaves identical from the standpoint of the callers.
322 This is done to replace a dependency that is h 308 This is done to replace a dependency that is hard to deal with, or is slow. For
323 example, implementing a fake EEPROM that store 309 example, implementing a fake EEPROM that stores the "contents" in an
324 internal buffer. Assume we have a class that r 310 internal buffer. Assume we have a class that represents an EEPROM:
325 311
326 .. code-block:: c 312 .. code-block:: c
327 313
328 struct eeprom { 314 struct eeprom {
329 ssize_t (*read)(struct eeprom 315 ssize_t (*read)(struct eeprom *this, size_t offset, char *buffer, size_t count);
330 ssize_t (*write)(struct eeprom 316 ssize_t (*write)(struct eeprom *this, size_t offset, const char *buffer, size_t count);
331 }; 317 };
332 318
333 And we want to test code that buffers writes t 319 And we want to test code that buffers writes to the EEPROM:
334 320
335 .. code-block:: c 321 .. code-block:: c
336 322
337 struct eeprom_buffer { 323 struct eeprom_buffer {
338 ssize_t (*write)(struct eeprom 324 ssize_t (*write)(struct eeprom_buffer *this, const char *buffer, size_t count);
339 int flush(struct eeprom_buffer 325 int flush(struct eeprom_buffer *this);
340 size_t flush_count; /* Flushes 326 size_t flush_count; /* Flushes when buffer exceeds flush_count. */
341 }; 327 };
342 328
343 struct eeprom_buffer *new_eeprom_buffe 329 struct eeprom_buffer *new_eeprom_buffer(struct eeprom *eeprom);
344 void destroy_eeprom_buffer(struct eepr 330 void destroy_eeprom_buffer(struct eeprom *eeprom);
345 331
346 We can test this code by *faking out* the unde 332 We can test this code by *faking out* the underlying EEPROM:
347 333
348 .. code-block:: c 334 .. code-block:: c
349 335
350 struct fake_eeprom { 336 struct fake_eeprom {
351 struct eeprom parent; 337 struct eeprom parent;
352 char contents[FAKE_EEPROM_CONT 338 char contents[FAKE_EEPROM_CONTENTS_SIZE];
353 }; 339 };
354 340
355 ssize_t fake_eeprom_read(struct eeprom 341 ssize_t fake_eeprom_read(struct eeprom *parent, size_t offset, char *buffer, size_t count)
356 { 342 {
357 struct fake_eeprom *this = con 343 struct fake_eeprom *this = container_of(parent, struct fake_eeprom, parent);
358 344
359 count = min(count, FAKE_EEPROM 345 count = min(count, FAKE_EEPROM_CONTENTS_SIZE - offset);
360 memcpy(buffer, this->contents 346 memcpy(buffer, this->contents + offset, count);
361 347
362 return count; 348 return count;
363 } 349 }
364 350
365 ssize_t fake_eeprom_write(struct eepro 351 ssize_t fake_eeprom_write(struct eeprom *parent, size_t offset, const char *buffer, size_t count)
366 { 352 {
367 struct fake_eeprom *this = con 353 struct fake_eeprom *this = container_of(parent, struct fake_eeprom, parent);
368 354
369 count = min(count, FAKE_EEPROM 355 count = min(count, FAKE_EEPROM_CONTENTS_SIZE - offset);
370 memcpy(this->contents + offset 356 memcpy(this->contents + offset, buffer, count);
371 357
372 return count; 358 return count;
373 } 359 }
374 360
375 void fake_eeprom_init(struct fake_eepr 361 void fake_eeprom_init(struct fake_eeprom *this)
376 { 362 {
377 this->parent.read = fake_eepro 363 this->parent.read = fake_eeprom_read;
378 this->parent.write = fake_eepr 364 this->parent.write = fake_eeprom_write;
379 memset(this->contents, 0, FAKE 365 memset(this->contents, 0, FAKE_EEPROM_CONTENTS_SIZE);
380 } 366 }
381 367
382 We can now use it to test ``struct eeprom_buff 368 We can now use it to test ``struct eeprom_buffer``:
383 369
384 .. code-block:: c 370 .. code-block:: c
385 371
386 struct eeprom_buffer_test { 372 struct eeprom_buffer_test {
387 struct fake_eeprom *fake_eepro 373 struct fake_eeprom *fake_eeprom;
388 struct eeprom_buffer *eeprom_b 374 struct eeprom_buffer *eeprom_buffer;
389 }; 375 };
390 376
391 static void eeprom_buffer_test_does_no 377 static void eeprom_buffer_test_does_not_write_until_flush(struct kunit *test)
392 { 378 {
393 struct eeprom_buffer_test *ctx 379 struct eeprom_buffer_test *ctx = test->priv;
394 struct eeprom_buffer *eeprom_b 380 struct eeprom_buffer *eeprom_buffer = ctx->eeprom_buffer;
395 struct fake_eeprom *fake_eepro 381 struct fake_eeprom *fake_eeprom = ctx->fake_eeprom;
396 char buffer[] = {0xff}; 382 char buffer[] = {0xff};
397 383
398 eeprom_buffer->flush_count = S 384 eeprom_buffer->flush_count = SIZE_MAX;
399 385
400 eeprom_buffer->write(eeprom_bu 386 eeprom_buffer->write(eeprom_buffer, buffer, 1);
401 KUNIT_EXPECT_EQ(test, fake_eep 387 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0);
402 388
403 eeprom_buffer->write(eeprom_bu 389 eeprom_buffer->write(eeprom_buffer, buffer, 1);
404 KUNIT_EXPECT_EQ(test, fake_eep 390 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[1], 0);
405 391
406 eeprom_buffer->flush(eeprom_bu 392 eeprom_buffer->flush(eeprom_buffer);
407 KUNIT_EXPECT_EQ(test, fake_eep 393 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0xff);
408 KUNIT_EXPECT_EQ(test, fake_eep 394 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[1], 0xff);
409 } 395 }
410 396
411 static void eeprom_buffer_test_flushes 397 static void eeprom_buffer_test_flushes_after_flush_count_met(struct kunit *test)
412 { 398 {
413 struct eeprom_buffer_test *ctx 399 struct eeprom_buffer_test *ctx = test->priv;
414 struct eeprom_buffer *eeprom_b 400 struct eeprom_buffer *eeprom_buffer = ctx->eeprom_buffer;
415 struct fake_eeprom *fake_eepro 401 struct fake_eeprom *fake_eeprom = ctx->fake_eeprom;
416 char buffer[] = {0xff}; 402 char buffer[] = {0xff};
417 403
418 eeprom_buffer->flush_count = 2 404 eeprom_buffer->flush_count = 2;
419 405
420 eeprom_buffer->write(eeprom_bu 406 eeprom_buffer->write(eeprom_buffer, buffer, 1);
421 KUNIT_EXPECT_EQ(test, fake_eep 407 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0);
422 408
423 eeprom_buffer->write(eeprom_bu 409 eeprom_buffer->write(eeprom_buffer, buffer, 1);
424 KUNIT_EXPECT_EQ(test, fake_eep 410 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0xff);
425 KUNIT_EXPECT_EQ(test, fake_eep 411 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[1], 0xff);
426 } 412 }
427 413
428 static void eeprom_buffer_test_flushes 414 static void eeprom_buffer_test_flushes_increments_of_flush_count(struct kunit *test)
429 { 415 {
430 struct eeprom_buffer_test *ctx 416 struct eeprom_buffer_test *ctx = test->priv;
431 struct eeprom_buffer *eeprom_b 417 struct eeprom_buffer *eeprom_buffer = ctx->eeprom_buffer;
432 struct fake_eeprom *fake_eepro 418 struct fake_eeprom *fake_eeprom = ctx->fake_eeprom;
433 char buffer[] = {0xff, 0xff}; 419 char buffer[] = {0xff, 0xff};
434 420
435 eeprom_buffer->flush_count = 2 421 eeprom_buffer->flush_count = 2;
436 422
437 eeprom_buffer->write(eeprom_bu 423 eeprom_buffer->write(eeprom_buffer, buffer, 1);
438 KUNIT_EXPECT_EQ(test, fake_eep 424 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0);
439 425
440 eeprom_buffer->write(eeprom_bu 426 eeprom_buffer->write(eeprom_buffer, buffer, 2);
441 KUNIT_EXPECT_EQ(test, fake_eep 427 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[0], 0xff);
442 KUNIT_EXPECT_EQ(test, fake_eep 428 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[1], 0xff);
443 /* Should have only flushed th 429 /* Should have only flushed the first two bytes. */
444 KUNIT_EXPECT_EQ(test, fake_eep 430 KUNIT_EXPECT_EQ(test, fake_eeprom->contents[2], 0);
445 } 431 }
446 432
447 static int eeprom_buffer_test_init(str 433 static int eeprom_buffer_test_init(struct kunit *test)
448 { 434 {
449 struct eeprom_buffer_test *ctx 435 struct eeprom_buffer_test *ctx;
450 436
451 ctx = kunit_kzalloc(test, size 437 ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
452 KUNIT_ASSERT_NOT_ERR_OR_NULL(t 438 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
453 439
454 ctx->fake_eeprom = kunit_kzall 440 ctx->fake_eeprom = kunit_kzalloc(test, sizeof(*ctx->fake_eeprom), GFP_KERNEL);
455 KUNIT_ASSERT_NOT_ERR_OR_NULL(t 441 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->fake_eeprom);
456 fake_eeprom_init(ctx->fake_eep 442 fake_eeprom_init(ctx->fake_eeprom);
457 443
458 ctx->eeprom_buffer = new_eepro 444 ctx->eeprom_buffer = new_eeprom_buffer(&ctx->fake_eeprom->parent);
459 KUNIT_ASSERT_NOT_ERR_OR_NULL(t 445 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->eeprom_buffer);
460 446
461 test->priv = ctx; 447 test->priv = ctx;
462 448
463 return 0; 449 return 0;
464 } 450 }
465 451
466 static void eeprom_buffer_test_exit(st 452 static void eeprom_buffer_test_exit(struct kunit *test)
467 { 453 {
468 struct eeprom_buffer_test *ctx 454 struct eeprom_buffer_test *ctx = test->priv;
469 455
470 destroy_eeprom_buffer(ctx->eep 456 destroy_eeprom_buffer(ctx->eeprom_buffer);
471 } 457 }
472 458
473 Testing Against Multiple Inputs 459 Testing Against Multiple Inputs
474 ------------------------------- 460 -------------------------------
475 461
476 Testing just a few inputs is not enough to ens 462 Testing just a few inputs is not enough to ensure that the code works correctly,
477 for example: testing a hash function. 463 for example: testing a hash function.
478 464
479 We can write a helper macro or function. The f 465 We can write a helper macro or function. The function is called for each input.
480 For example, to test ``sha1sum(1)``, we can wr 466 For example, to test ``sha1sum(1)``, we can write:
481 467
482 .. code-block:: c 468 .. code-block:: c
483 469
484 #define TEST_SHA1(in, want) \ 470 #define TEST_SHA1(in, want) \
485 sha1sum(in, out); \ 471 sha1sum(in, out); \
486 KUNIT_EXPECT_STREQ_MSG(test, o 472 KUNIT_EXPECT_STREQ_MSG(test, out, want, "sha1sum(%s)", in);
487 473
488 char out[40]; 474 char out[40];
489 TEST_SHA1("hello world", "2aae6c35c94 475 TEST_SHA1("hello world", "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed");
490 TEST_SHA1("hello world!", "430ce34d020 476 TEST_SHA1("hello world!", "430ce34d020724ed75a196dfc2ad67c77772d169");
491 477
492 Note the use of the ``_MSG`` version of ``KUNI 478 Note the use of the ``_MSG`` version of ``KUNIT_EXPECT_STREQ`` to print a more
493 detailed error and make the assertions clearer 479 detailed error and make the assertions clearer within the helper macros.
494 480
495 The ``_MSG`` variants are useful when the same 481 The ``_MSG`` variants are useful when the same expectation is called multiple
496 times (in a loop or helper function) and thus 482 times (in a loop or helper function) and thus the line number is not enough to
497 identify what failed, as shown below. 483 identify what failed, as shown below.
498 484
499 In complicated cases, we recommend using a *ta 485 In complicated cases, we recommend using a *table-driven test* compared to the
500 helper macro variation, for example: 486 helper macro variation, for example:
501 487
502 .. code-block:: c 488 .. code-block:: c
503 489
504 int i; 490 int i;
505 char out[40]; 491 char out[40];
506 492
507 struct sha1_test_case { 493 struct sha1_test_case {
508 const char *str; 494 const char *str;
509 const char *sha1; 495 const char *sha1;
510 }; 496 };
511 497
512 struct sha1_test_case cases[] = { 498 struct sha1_test_case cases[] = {
513 { 499 {
514 .str = "hello world", 500 .str = "hello world",
515 .sha1 = "2aae6c35c94fc 501 .sha1 = "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",
516 }, 502 },
517 { 503 {
518 .str = "hello world!", 504 .str = "hello world!",
519 .sha1 = "430ce34d02072 505 .sha1 = "430ce34d020724ed75a196dfc2ad67c77772d169",
520 }, 506 },
521 }; 507 };
522 for (i = 0; i < ARRAY_SIZE(cases); ++i 508 for (i = 0; i < ARRAY_SIZE(cases); ++i) {
523 sha1sum(cases[i].str, out); 509 sha1sum(cases[i].str, out);
524 KUNIT_EXPECT_STREQ_MSG(test, o 510 KUNIT_EXPECT_STREQ_MSG(test, out, cases[i].sha1,
525 "sha1sum 511 "sha1sum(%s)", cases[i].str);
526 } 512 }
527 513
528 514
529 There is more boilerplate code involved, but i 515 There is more boilerplate code involved, but it can:
530 516
531 * be more readable when there are multiple inp 517 * be more readable when there are multiple inputs/outputs (due to field names).
532 518
533 * For example, see ``fs/ext4/inode-test.c``. 519 * For example, see ``fs/ext4/inode-test.c``.
534 520
535 * reduce duplication if test cases are shared 521 * reduce duplication if test cases are shared across multiple tests.
536 522
537 * For example: if we want to test ``sha256su 523 * For example: if we want to test ``sha256sum``, we could add a ``sha256``
538 field and reuse ``cases``. 524 field and reuse ``cases``.
539 525
540 * be converted to a "parameterized test". 526 * be converted to a "parameterized test".
541 527
542 Parameterized Testing 528 Parameterized Testing
543 ~~~~~~~~~~~~~~~~~~~~~ 529 ~~~~~~~~~~~~~~~~~~~~~
544 530
545 The table-driven testing pattern is common eno 531 The table-driven testing pattern is common enough that KUnit has special
546 support for it. 532 support for it.
547 533
548 By reusing the same ``cases`` array from above 534 By reusing the same ``cases`` array from above, we can write the test as a
549 "parameterized test" with the following. 535 "parameterized test" with the following.
550 536
551 .. code-block:: c 537 .. code-block:: c
552 538
553 // This is copy-pasted from above. 539 // This is copy-pasted from above.
554 struct sha1_test_case { 540 struct sha1_test_case {
555 const char *str; 541 const char *str;
556 const char *sha1; 542 const char *sha1;
557 }; 543 };
558 const struct sha1_test_case cases[] = 544 const struct sha1_test_case cases[] = {
559 { 545 {
560 .str = "hello world", 546 .str = "hello world",
561 .sha1 = "2aae6c35c94fc 547 .sha1 = "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",
562 }, 548 },
563 { 549 {
564 .str = "hello world!", 550 .str = "hello world!",
565 .sha1 = "430ce34d02072 551 .sha1 = "430ce34d020724ed75a196dfc2ad67c77772d169",
566 }, 552 },
567 }; 553 };
568 554
569 // Creates `sha1_gen_params()` to iter !! 555 // Need a helper function to generate a name for each test case.
570 // the struct member `str` for the cas !! 556 static void case_to_desc(const struct sha1_test_case *t, char *desc)
571 KUNIT_ARRAY_PARAM_DESC(sha1, cases, st !! 557 {
>> 558 strcpy(desc, t->str);
>> 559 }
>> 560 // Creates `sha1_gen_params()` to iterate over `cases`.
>> 561 KUNIT_ARRAY_PARAM(sha1, cases, case_to_desc);
572 562
573 // Looks no different from a normal te 563 // Looks no different from a normal test.
574 static void sha1_test(struct kunit *te 564 static void sha1_test(struct kunit *test)
575 { 565 {
576 // This function can just cont 566 // This function can just contain the body of the for-loop.
577 // The former `cases[i]` is ac 567 // The former `cases[i]` is accessible under test->param_value.
578 char out[40]; 568 char out[40];
579 struct sha1_test_case *test_pa 569 struct sha1_test_case *test_param = (struct sha1_test_case *)(test->param_value);
580 570
581 sha1sum(test_param->str, out); 571 sha1sum(test_param->str, out);
582 KUNIT_EXPECT_STREQ_MSG(test, o 572 KUNIT_EXPECT_STREQ_MSG(test, out, test_param->sha1,
583 "sha1sum 573 "sha1sum(%s)", test_param->str);
584 } 574 }
585 575
586 // Instead of KUNIT_CASE, we use KUNIT 576 // Instead of KUNIT_CASE, we use KUNIT_CASE_PARAM and pass in the
587 // function declared by KUNIT_ARRAY_PA !! 577 // function declared by KUNIT_ARRAY_PARAM.
588 static struct kunit_case sha1_test_cas 578 static struct kunit_case sha1_test_cases[] = {
589 KUNIT_CASE_PARAM(sha1_test, sh 579 KUNIT_CASE_PARAM(sha1_test, sha1_gen_params),
590 {} 580 {}
591 }; 581 };
592 582
593 Allocating Memory 583 Allocating Memory
594 ----------------- 584 -----------------
595 585
596 Where you might use ``kzalloc``, you can inste 586 Where you might use ``kzalloc``, you can instead use ``kunit_kzalloc`` as KUnit
597 will then ensure that the memory is freed once 587 will then ensure that the memory is freed once the test completes.
598 588
599 This is useful because it lets us use the ``KU 589 This is useful because it lets us use the ``KUNIT_ASSERT_EQ`` macros to exit
600 early from a test without having to worry abou 590 early from a test without having to worry about remembering to call ``kfree``.
601 For example: 591 For example:
602 592
603 .. code-block:: c 593 .. code-block:: c
604 594
605 void example_test_allocation(struct ku 595 void example_test_allocation(struct kunit *test)
606 { 596 {
607 char *buffer = kunit_kzalloc(t 597 char *buffer = kunit_kzalloc(test, 16, GFP_KERNEL);
608 /* Ensure allocation succeeded 598 /* Ensure allocation succeeded. */
609 KUNIT_ASSERT_NOT_ERR_OR_NULL(t 599 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buffer);
610 600
611 KUNIT_ASSERT_STREQ(test, buffe 601 KUNIT_ASSERT_STREQ(test, buffer, "");
612 } 602 }
613 603
614 Registering Cleanup Actions <<
615 --------------------------- <<
616 <<
617 If you need to perform some cleanup beyond sim <<
618 you can register a custom "deferred action", w <<
619 run when the test exits (whether cleanly, or v <<
620 <<
621 Actions are simple functions with no return va <<
622 context argument, and fulfill the same role as <<
623 and Go tests, "defer" statements in languages <<
624 (in some cases) destructors in RAII languages. <<
625 <<
626 These are very useful for unregistering things <<
627 files or other resources, or freeing resources <<
628 <<
629 For example: <<
630 <<
631 .. code-block:: C <<
632 <<
633 static void cleanup_device(void *ctx) <<
634 { <<
635 struct device *dev = (struct d <<
636 <<
637 device_unregister(dev); <<
638 } <<
639 <<
640 void example_device_test(struct kunit <<
641 { <<
642 struct my_device dev; <<
643 <<
644 device_register(&dev); <<
645 <<
646 kunit_add_action(test, &cleanu <<
647 } <<
648 <<
649 Note that, for functions like device_unregiste <<
650 pointer-sized argument, it's possible to autom <<
651 with the ``KUNIT_DEFINE_ACTION_WRAPPER()`` mac <<
652 <<
653 .. code-block:: C <<
654 <<
655 KUNIT_DEFINE_ACTION_WRAPPER(device_unr <<
656 kunit_add_action(test, &device_unregis <<
657 <<
658 You should do this in preference to manually c <<
659 as casting function pointers will break Contro <<
660 <<
661 ``kunit_add_action`` can fail if, for example, <<
662 You can use ``kunit_add_action_or_reset`` inst <<
663 immediately if it cannot be deferred. <<
664 <<
665 If you need more control over when the cleanup <<
666 can trigger it early using ``kunit_release_act <<
667 with ``kunit_remove_action``. <<
668 <<
669 604
670 Testing Static Functions 605 Testing Static Functions
671 ------------------------ 606 ------------------------
672 607
673 If we do not want to expose functions or varia 608 If we do not want to expose functions or variables for testing, one option is to
674 conditionally export the used symbol. For exam !! 609 conditionally ``#include`` the test file at the end of your .c file. For
675 !! 610 example:
676 .. code-block:: c <<
677 <<
678 /* In my_file.c */ <<
679 <<
680 VISIBLE_IF_KUNIT int do_interesting_th <<
681 EXPORT_SYMBOL_IF_KUNIT(do_interesting_ <<
682 <<
683 /* In my_file.h */ <<
684 <<
685 #if IS_ENABLED(CONFIG_KUNIT) <<
686 int do_interesting_thing(void) <<
687 #endif <<
688 <<
689 Alternatively, you could conditionally ``#incl <<
690 your .c file. For example: <<
691 611
692 .. code-block:: c 612 .. code-block:: c
693 613
694 /* In my_file.c */ 614 /* In my_file.c */
695 615
696 static int do_interesting_thing(); 616 static int do_interesting_thing();
697 617
698 #ifdef CONFIG_MY_KUNIT_TEST 618 #ifdef CONFIG_MY_KUNIT_TEST
699 #include "my_kunit_test.c" 619 #include "my_kunit_test.c"
700 #endif 620 #endif
701 621
702 Injecting Test-Only Code 622 Injecting Test-Only Code
703 ------------------------ 623 ------------------------
704 624
705 Similar to as shown above, we can add test-spe 625 Similar to as shown above, we can add test-specific logic. For example:
706 626
707 .. code-block:: c 627 .. code-block:: c
708 628
709 /* In my_file.h */ 629 /* In my_file.h */
710 630
711 #ifdef CONFIG_MY_KUNIT_TEST 631 #ifdef CONFIG_MY_KUNIT_TEST
712 /* Defined in my_kunit_test.c */ 632 /* Defined in my_kunit_test.c */
713 void test_only_hook(void); 633 void test_only_hook(void);
714 #else 634 #else
715 void test_only_hook(void) { } 635 void test_only_hook(void) { }
716 #endif 636 #endif
717 637
718 This test-only code can be made more useful by 638 This test-only code can be made more useful by accessing the current ``kunit_test``
719 as shown in next section: *Accessing The Curre 639 as shown in next section: *Accessing The Current Test*.
720 640
721 Accessing The Current Test 641 Accessing The Current Test
722 -------------------------- 642 --------------------------
723 643
724 In some cases, we need to call test-only code 644 In some cases, we need to call test-only code from outside the test file. This
725 is helpful, for example, when providing a fake 645 is helpful, for example, when providing a fake implementation of a function, or
726 to fail any current test from within an error 646 to fail any current test from within an error handler.
727 We can do this via the ``kunit_test`` field in 647 We can do this via the ``kunit_test`` field in ``task_struct``, which we can
728 access using the ``kunit_get_current_test()`` 648 access using the ``kunit_get_current_test()`` function in ``kunit/test-bug.h``.
729 649
730 ``kunit_get_current_test()`` is safe to call e 650 ``kunit_get_current_test()`` is safe to call even if KUnit is not enabled. If
731 KUnit is not enabled, or if no test is running !! 651 KUnit is not enabled, was built as a module (``CONFIG_KUNIT=m``), or no test is
732 return ``NULL``. This compiles down to either !! 652 running in the current task, it will return ``NULL``. This compiles down to
733 so will have a negligible performance impact w !! 653 either a no-op or a static key check, so will have a negligible performance
>> 654 impact when no test is running.
734 655
735 The example below uses this to implement a "mo 656 The example below uses this to implement a "mock" implementation of a function, ``foo``:
736 657
737 .. code-block:: c 658 .. code-block:: c
738 659
739 #include <kunit/test-bug.h> /* for kun 660 #include <kunit/test-bug.h> /* for kunit_get_current_test */
740 661
741 struct test_data { 662 struct test_data {
742 int foo_result; 663 int foo_result;
743 int want_foo_called_with; 664 int want_foo_called_with;
744 }; 665 };
745 666
746 static int fake_foo(int arg) 667 static int fake_foo(int arg)
747 { 668 {
748 struct kunit *test = kunit_get 669 struct kunit *test = kunit_get_current_test();
749 struct test_data *test_data = 670 struct test_data *test_data = test->priv;
750 671
751 KUNIT_EXPECT_EQ(test, test_dat 672 KUNIT_EXPECT_EQ(test, test_data->want_foo_called_with, arg);
752 return test_data->foo_result; 673 return test_data->foo_result;
753 } 674 }
754 675
755 static void example_simple_test(struct 676 static void example_simple_test(struct kunit *test)
756 { 677 {
757 /* Assume priv (private, a mem 678 /* Assume priv (private, a member used to pass test data from
758 * the init function) is alloc 679 * the init function) is allocated in the suite's .init */
759 struct test_data *test_data = 680 struct test_data *test_data = test->priv;
760 681
761 test_data->foo_result = 42; 682 test_data->foo_result = 42;
762 test_data->want_foo_called_wit 683 test_data->want_foo_called_with = 1;
763 684
764 /* In a real test, we'd probab 685 /* In a real test, we'd probably pass a pointer to fake_foo somewhere
765 * like an ops struct, etc. in 686 * like an ops struct, etc. instead of calling it directly. */
766 KUNIT_EXPECT_EQ(test, fake_foo 687 KUNIT_EXPECT_EQ(test, fake_foo(1), 42);
767 } 688 }
768 689
769 In this example, we are using the ``priv`` mem 690 In this example, we are using the ``priv`` member of ``struct kunit`` as a way
770 of passing data to the test from the init func 691 of passing data to the test from the init function. In general ``priv`` is
771 pointer that can be used for any user data. Th 692 pointer that can be used for any user data. This is preferred over static
772 variables, as it avoids concurrency issues. 693 variables, as it avoids concurrency issues.
773 694
774 Had we wanted something more flexible, we coul 695 Had we wanted something more flexible, we could have used a named ``kunit_resource``.
775 Each test can have multiple resources which ha 696 Each test can have multiple resources which have string names providing the same
776 flexibility as a ``priv`` member, but also, fo 697 flexibility as a ``priv`` member, but also, for example, allowing helper
777 functions to create resources without conflict 698 functions to create resources without conflicting with each other. It is also
778 possible to define a clean up function for eac 699 possible to define a clean up function for each resource, making it easy to
779 avoid resource leaks. For more information, se 700 avoid resource leaks. For more information, see Documentation/dev-tools/kunit/api/resource.rst.
780 701
781 Failing The Current Test 702 Failing The Current Test
782 ------------------------ 703 ------------------------
783 704
784 If we want to fail the current test, we can us 705 If we want to fail the current test, we can use ``kunit_fail_current_test(fmt, args...)``
785 which is defined in ``<kunit/test-bug.h>`` and 706 which is defined in ``<kunit/test-bug.h>`` and does not require pulling in ``<kunit/test.h>``.
786 For example, we have an option to enable some 707 For example, we have an option to enable some extra debug checks on some data
787 structures as shown below: 708 structures as shown below:
788 709
789 .. code-block:: c 710 .. code-block:: c
790 711
791 #include <kunit/test-bug.h> 712 #include <kunit/test-bug.h>
792 713
793 #ifdef CONFIG_EXTRA_DEBUG_CHECKS 714 #ifdef CONFIG_EXTRA_DEBUG_CHECKS
794 static void validate_my_data(struct da 715 static void validate_my_data(struct data *data)
795 { 716 {
796 if (is_valid(data)) 717 if (is_valid(data))
797 return; 718 return;
798 719
799 kunit_fail_current_test("data 720 kunit_fail_current_test("data %p is invalid", data);
800 721
801 /* Normal, non-KUnit, error re 722 /* Normal, non-KUnit, error reporting code here. */
802 } 723 }
803 #else 724 #else
804 static void my_debug_function(void) { 725 static void my_debug_function(void) { }
805 #endif 726 #endif
806 727
807 ``kunit_fail_current_test()`` is safe to call 728 ``kunit_fail_current_test()`` is safe to call even if KUnit is not enabled. If
808 KUnit is not enabled, or if no test is running !! 729 KUnit is not enabled, was built as a module (``CONFIG_KUNIT=m``), or no test is
809 nothing. This compiles down to either a no-op !! 730 running in the current task, it will do nothing. This compiles down to either a
810 have a negligible performance impact when no t !! 731 no-op or a static key check, so will have a negligible performance impact when
811 !! 732 no test is running.
812 Managing Fake Devices and Drivers <<
813 --------------------------------- <<
814 <<
815 When testing drivers or code which interacts w <<
816 require a ``struct device`` or ``struct device <<
817 up a real device is not required to test any g <<
818 can be used instead. <<
819 <<
820 KUnit provides helper functions to create and <<
821 are internally of type ``struct kunit_device`` <<
822 ``kunit_bus``. These devices support managed d <<
823 described in Documentation/driver-api/driver-m <<
824 <<
825 To create a KUnit-managed ``struct device_driv <<
826 which will create a driver with the given name <<
827 will automatically be destroyed when the corre <<
828 be manually destroyed with ``driver_unregister <<
829 <<
830 To create a fake device, use the ``kunit_devic <<
831 and register a device, using a new KUnit-manag <<
832 To provide a specific, non-KUnit-managed drive <<
833 instead. Like with managed drivers, KUnit-mana <<
834 cleaned up when the test finishes, but can be <<
835 ``kunit_device_unregister()``. <<
836 <<
837 The KUnit devices should be used in preference <<
838 instead of ``platform_device_register()`` in c <<
839 a platform device. <<
840 <<
841 For example: <<
842 <<
843 .. code-block:: c <<
844 <<
845 #include <kunit/device.h> <<
846 <<
847 static void test_my_device(struct kuni <<
848 { <<
849 struct device *fake_device; <<
850 const char *dev_managed_string <<
851 <<
852 // Create a fake device. <<
853 fake_device = kunit_device_reg <<
854 KUNIT_ASSERT_NOT_ERR_OR_NULL(t <<
855 <<
856 // Pass it to functions which <<
857 dev_managed_string = devm_kstr <<
858 733
859 // Everything is cleaned up au <<
860 } <<
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