aboutsummaryrefslogtreecommitdiff
path: root/doc/index.html
blob: 5f7c5a7233597df67fc92e0620471b905906a3c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html><head>
<title>cmocka</title>
</head>
<body>
<h1>cmocka Unit Testing Framework</h1>
<p>cmocka is a lightweight library that is used to author C unit tests.</p>

<ul>Contents
  <li><a href="#Motivation">Motivation</a></li>
  <li><a href="#Overview">Overview</a></li>
  <li><a href="#Test_Execution">Test Execution</a>
  <li><a href="#Exception_Handling">Exception Handling</a></li>
  <li><a href="#Failure_Conditions">Failure Conditions</a></li>
  <li><a href="#Assertions">Assertions</a></li>
  <ul>
    <li><a href="#Assert_Macros">Assert Macros</a></li>
  </ul>
  <li><a href="#Dynamic_Memory_Allocation">Dynamic Memory Allocation</a></li>
  <li><a href="#Mock_Functions">Mock functions</a></li>
  <ul>
    <li><a href="#Return_Values">Return Values</a></li>
    <li><a href="#Checking_Parameters">Checking Parameters</a></li>
  </ul>
  <li><a href="#Test_State">Test State</a></li>
  <li><a href="#Example">Example</a></li>
</ul>

<a name="Motivation"><h2>Motivation</h2></a>
<p>There are a variety of C unit testing frameworks available however many of
them are fairly complex and require the latest compiler technology.  Some
development requires the use of old compilers which makes it difficult to
use some unit testing frameworks.  In addition many unit testing frameworks
assume the code being tested is an application or module that is targeted to
the same platform that will ultimately execute the test.  Because of this
assumption many frameworks require the inclusion of standard C library headers
in the code module being tested which may collide with the custom or
incomplete implementation of the C library utilized by the code under test.</p>

<p>cmocka only requires a test application is linked with the standard C
library which minimizes conflicts with standard C library headers.  Also,
cmocka tries avoid the use of some of the newer features of C compilers.</p>

<p>This results in cmocka being a relatively small library that can be used
to test a variety of exotic code.  If a developer wishes to simply test an
application with the latest compiler then other unit testing frameworks maybe
preferable.</p>

<a name="Overview"><h2>Overview</h2></a>
<p>cmocka tests are compiled into stand-alone executables and linked with
the cmocka library, the standard C library and module being tested.  Any
symbols external to the module being tested should be mocked - replaced with 
functions that return values determined by the test - within the test
application.  Even though significant differences may exist between the target
execution environment of a code module and the environment used to test the
code the unit testing is still valid since its goal is to test the logic of a
code modules at a functional level and not necessarily all of its interactions
with the target execution environment.</p>

<p>It may not be possible to compile a module into a test application without
some modification, therefore the preprocessor symbol <b>UNIT_TESTING</b> should
be defined when cmocka unit test applications are compiled so code within the
module can be conditionally compiled for tests.</p>

<a name="Test_Execution"><h2>Test Execution</h2></a>
<p>cmocka unit test cases are functions with the signature
<b>void function(void **state)</b>.  cmocka test applications initialize a
table with test case function pointers using <b>unit_test*()</b> macros.  This
table is then passed to the <b>run_tests()</b> macro to execute the tests.

<b>run_tests()</b> sets up the appropriate exception / signal handlers and
other data structures prior to running each test function.   When a unit test
is complete <b>run_tests()</b> performs various checks to determine whether
the test succeeded.</p>

<h4>Using run_tests()</h4>
<a href="../example/run_tests.c">run_tests.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;

// A test case that does nothing and succeeds.
void null_test_success(void **state) {
}

int main(int argc, char* argv[]) {
    const UnitTest tests[] = {
        unit_test(null_test_success),
    };
    return run_tests(tests);
}
</listing>

<a name="Exception_Handling"><h2>Exception Handling</h2></a>
<p>Before a test function is executed by <b>run_tests()</b>,
exception / signal handlers are overridden with a handler that simply
displays an error and exits a test function if an exception occurs.  If an
exception occurs outside of a test function, for example in cmocka itself,
the application aborts execution and returns an error code.</p>

<a name="Failure_Conditions"><h2>Failure Conditions</h2></a>
<p>If a failure occurs during a test function that's executed via
<b>run_tests()</b>, the test function is aborted and the application's
execution resumes with the next test function.

Test failures are ultimately signalled via the cmocka function <b>fail()</b>.
The following events will result in the cmocka library signalling a test
failure...

<ul>
  <li><a href="#Assertions">Assertions</a></li>
  <li><a href="#Exception_Handling">Exceptions</a></li>
  <li><a href="#Dynamic_Memory_Allocation">Memory leaks</a></li>
  <li><a href="#Test_State">Mismatched setup and tear down functions</a></li>
  <li><a href="#Return_Values">Missing mock return values</a></li>
  <li><a href="#Return_Values">Unused mock return values</a></li>
  <li><a href="#Checking_Parameters">Missing expected parameter values</a></li>
  <li><a href="#Checking_Parameters">Unused expected parameter values</a></li>
</ul>
</p>

<a name="Assertions"><h2>Assertions</h2></a>
<p>Runtime assert macros like the standard C library's <b>assert()</b> should
be redefined in modules being tested to use cmocka's <b>mock_assert()</b>
function.  Normally <b>mock_assert()</b> signals a
<a href="#Failure_Conditions">test failure</a>.  If a function is called using
the <b>expect_assert_failure()</b> macro, any calls to <b>mock_assert()</b>
within the function will result in the execution of the test.  If no
calls to <b>mock_assert()</b> occur during the function called via
<b>expect_assert_failure()</b> a test failure is signalled.</p>

<h4>Using mock_assert()</h4>
<a href="../example/assert_module.c">assert_module.c</a>
<listing>
#include &lt;assert.h&gt;

// If unit testing is enabled override assert with mock_assert().
#ifdef UNIT_TESTING
extern void mock_assert(const int result, const char* const expression, 
                        const char * const file, const int line);
#undef assert
#define assert(expression) \
    mock_assert((int)(expression), #expression, __FILE__, __LINE__);
#endif // UNIT_TESTING

void increment_value(int * const value) {
    assert(value);
    (*value) ++;
}

void decrement_value(int * const value) {
    if (value) {
        *value --;
    }
}
</listing>
<a href="../example/assert_module_test.c">assert_module_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;

extern void increment_value(int * const value);

/* This test case will fail but the assert is caught by run_tests() and the
 * next test is executed. */
void increment_value_fail(void **state) {
    increment_value(NULL);
}

// This test case succeeds since increment_value() asserts on the NULL pointer.
void increment_value_assert(void **state) {
    expect_assert_failure(increment_value(NULL));
}

/* This test case fails since decrement_value() doesn't assert on a NULL
 * pointer. */
void decrement_value_fail(void **state) {
    expect_assert_failure(decrement_value(NULL));
}

int main(int argc, char *argv[]) {
    const UnitTest tests[] = {
        unit_test(increment_value_fail),
        unit_test(increment_value_assert),
        unit_test(decrement_value_fail),
    };
    return run_tests(tests);
}
</listing>

<h3><a name="Assert_Macros">Assert Macros</a></h3>

<p>cmocka provides an assortment of assert macros that tests applications
should use use in preference to the C standard library's assert macro.  On an
assertion failure a cmocka assert macro will write the failure to the
standard error stream and signal a test failure.  Due to limitations of the
C language the general C standard library assert() and cmocka's
assert_true() and assert_false() macros can only display the expression that
caused the assert failure.  cmocka's type specific assert macros,
assert_{type}_equal() and assert_{type}_not_equal(), display the data that
caused the assertion failure which increases data visibility aiding
debugging of failing test cases.</p>

<h4>Using assert_{type}_equal() macros</h4>
<a href="../example/assert_macro.c">assert_macro.c</a>
<listing>
#include &lt;string.h&gt;

static const char* status_code_strings[] = {
    "Address not found",
    "Connection dropped",
    "Connection timed out",
};

const char* get_status_code_string(const unsigned int status_code) {
    return status_code_strings[status_code];
};

unsigned int string_to_status_code(const char* const status_code_string) {
    unsigned int i;
    for (i = 0; i < sizeof(status_code_strings) /
                    sizeof(status_code_strings[0]); i++) {
        if (strcmp(status_code_strings[i], status_code_string) == 0) {
            return i;
        }
    }
    return ~0U;
}
</listing>
<a href="../example/assert_macro_test.c">assert_macro_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;

extern const char* get_status_code_string(const unsigned int status_code);
extern unsigned int string_to_status_code(
    const char* const status_code_string);

/* This test will fail since the string returned by get_status_code_string(0)
 * doesn't match "Connection timed out". */
void get_status_code_string_test(void **state) {
    assert_string_equal(get_status_code_string(0), "Address not found");
    assert_string_equal(get_status_code_string(1), "Connection timed out");
}

// This test will fail since the status code of "Connection timed out" isn't 1
void string_to_status_code_test(void **state) {
    assert_int_equal(string_to_status_code("Address not found"), 0);
    assert_int_equal(string_to_status_code("Connection timed out"), 1);
}

int main(int argc, char *argv[]) {
    const UnitTest tests[] = {
        unit_test(get_status_code_string_test),
        unit_test(string_to_status_code_test),
    };
    return run_tests(tests);
}
</listing>

<a name="Dynamic_Memory_Allocation"><h2>Dynamic Memory Allocation</h2></a>

<p>To test for memory leaks, buffer overflows and underflows a module being
tested by cmocka should replace calls to <b>malloc()</b>, <b>calloc()</b> and
<b>free()</b> to <b>test_malloc()</b>, <b>test_calloc()</b> and
<b>test_free()</b> respectively.  Each time a block is deallocated using
<b>test_free()</b> it is checked for corruption, if a corrupt block is found
a <a href="#Failure_Conditions">test failure</a> is signalled.  All blocks
allocated using the <b>test_*()</b> allocation functions are tracked by the
cmocka library.  When a test completes if any allocated blocks (memory leaks)
remain they are reported and a test failure is signalled.</p>
<p>For simplicity cmocka currently executes all tests in one process.
Therefore all test cases in a test application share a single address space
which means memory corruption from a single test case could potentially cause
the test application to exit prematurely.</p>

<h4>Using cmocka's Allocators</h4>
<a href="../example/allocate_module.c">allocate_module.c</a>
<listing>
#include &lt;malloc.h&gt;

#ifdef UNIT_TESTING
extern void* _test_malloc(const size_t size, const char* file, const int line);
extern void* _test_calloc(const size_t number_of_elements, const size_t size, 
                          const char* file, const int line);
extern void _test_free(void* const ptr, const char* file, const int line);

#define malloc(size) _test_malloc(size, __FILE__, __LINE__)
#define calloc(num, size) _test_calloc(num, size, __FILE__, __LINE__)
#define free(ptr) _test_free(ptr, __FILE__, __LINE__)
#endif // UNIT_TESTING

void leak_memory() {
    int * const temporary = (int*)malloc(sizeof(int));
    *temporary = 0;
}

void buffer_overflow() {
    char * const memory = (char*)malloc(sizeof(int));
    memory[sizeof(int)] = '!';
    free(memory);
}

void buffer_underflow() {
    char * const memory = (char*)malloc(sizeof(int));
    memory[-1] = '!';
    free(memory);
}
</listing>
<a href="../example/allocate_module_test.c">allocate_module_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;

extern void leak_memory();
extern void buffer_overflow();
extern void buffer_underflow();

// Test case that fails as leak_memory() leaks a dynamically allocated block.
void leak_memory_test(void **state) {
    leak_memory();
}

// Test case that fails as buffer_overflow() corrupts an allocated block.
void buffer_overflow_test(void **state) {
    buffer_overflow();
}

// Test case that fails as buffer_underflow() corrupts an allocated block.
void buffer_underflow_test(void **state) {
    buffer_underflow();
}

int main(int argc, char* argv[]) {
    const UnitTest tests[] = {
        unit_test(leak_memory_test),
        unit_test(buffer_overflow_test),
        unit_test(buffer_underflow_test),
    };
    return run_tests(tests);
}
</listing>

<a name="Mock_Functions"><h2>Mock Functions</h2></a>

<p>A unit test should ideally isolate the function or module being tested
from any external dependencies.  This can be performed using mock functions
that are either statically or dynamically linked with the module being tested.
Mock functions must be statically linked when the code being tested directly 
references external functions.  Dynamic linking is simply the process of 
setting a function pointer in a table used by the tested module to reference 
a mock function defined in the unit test.</p>

<a name="Return_Values"><h3>Return Values</h3></a>

<p>In order to simplify the implementation of mock functions cmocka provides
functionality which stores return values for mock functions in each test
case using <b>will_return()</b>.  These values are then returned by each mock 
function using calls to <b>mock()</b>.

Values passed to <b>will_return()</b> are added to a queue for each function 
specified.  Each successive call to <b>mock()</b> from a function removes a
return value from the queue.  This makes it possible for a mock function to use
multiple calls to <b>mock()</b> to return output parameters in addition to a
return value.  In addition this allows the specification of return values for 
multiple calls to a mock function.</p>

<h4>Using will_return()</h4>
<a href="../example/database.h">database.h</a>
<listing>
typedef struct DatabaseConnection DatabaseConnection;

/* Function that takes an SQL query string and sets results to an array of
 * pointers with the result of the query.  The value returned specifies the
 * number of items in the returned array of results.  The returned array of
 * results are statically allocated and should not be deallocated using free()
 */
typedef unsigned int (*QueryDatabase)(
    DatabaseConnection* const connection, const char * const query_string,
    void *** const results);

// Connection to a database.
struct DatabaseConnection {
    const char *url;
    unsigned int port;
    QueryDatabase query_database;
};

// Connect to a database.
DatabaseConnection* connect_to_database(const char * const url,
                                        const unsigned int port);
</listing>
<a href="../example/customer_database.c">customer_database.c</a>
<listing>
#include &lt;stddef.h&gt;
#include &lt;stdio.h&gt;
#include &lt;database.h&gt;
#ifdef _WIN32
#define snprintf _snprintf
#endif // _WIN32

// Connect to the database containing customer information.
DatabaseConnection* connect_to_customer_database() {
    return connect_to_database("customers.abcd.org", 321);
}

/* Find the ID of a customer by his/her name returning a value > 0 if
 * successful, 0 otherwise. */
unsigned int get_customer_id_by_name(
        DatabaseConnection * const connection,
        const char * const customer_name) {
    char query_string[256];
    int number_of_results;
    void **results;
    snprintf(query_string, sizeof(query_string),
             "SELECT ID FROM CUSTOMERS WHERE NAME = %s", customer_name);
    number_of_results = connection->query_database(connection, query_string,
                                                   &results);
    if (number_of_results != 1) {
        return -1;
    }
    return (unsigned int)results[0];
}
</listing>
<a href="../example/customer_database_test.c">customer_database_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;
#include &lt;database.h&gt;


extern DatabaseConnection* connect_to_customer_database();
extern unsigned int get_customer_id_by_name(
    DatabaseConnection * const connection, const char * const customer_name);

// Mock query database function.
unsigned int mock_query_database(
        DatabaseConnection* const connection, const char * const query_string,
        void *** const results) {
    *results = (void**)mock();
    return (unsigned int)mock();
}

// Mock of the connect to database function.
DatabaseConnection* connect_to_database(const char * const database_url,
                                        const unsigned int port) {
    return (DatabaseConnection*)mock();
}

void test_connect_to_customer_database(void **state) {
    will_return(connect_to_database, 0x0DA7ABA53);
    assert_true(connect_to_customer_database() ==
                (DatabaseConnection*)0x0DA7ABA53);
}

/* This test fails as the mock function connect_to_database() will have no
 * value to return. */
void fail_connect_to_customer_database(void **state) {
    will_return(connect_to_database, 0x0DA7ABA53);
    assert_true(connect_to_customer_database() ==
                (DatabaseConnection*)0x0DA7ABA53);
}

void test_get_customer_id_by_name(void **state) {
    DatabaseConnection connection = {
        "somedatabase.somewhere.com", 12345678, mock_query_database
    };
    // Return a single customer ID when mock_query_database() is called.
    int customer_ids = 543;
    will_return(mock_query_database, &customer_ids);
    will_return(mock_query_database, 1);
    assert_int_equal(get_customer_id_by_name(&connection, "john doe"), 543);
}

int main(int argc, char* argv[]) {
    const UnitTest tests[] = {
        unit_test(test_connect_to_customer_database),
        unit_test(fail_connect_to_customer_database),
        unit_test(test_get_customer_id_by_name),
    };
    return run_tests(tests);
}
</listing>

<a name="Checking_Parameters"><h3>Checking Parameters</h3></a>
<p>In addition to storing the return values of mock functions, cmocka
provides functionality to store expected values for mock function parameters
using the expect_*() functions provided.  A mock function parameter can then
be validated using the check_expected() macro.

<p>Successive calls to expect_*() macros for a parameter queues values to
check the specified parameter.  check_expected() checks a function parameter
against the next value queued using expect_*(), if the parameter check fails a
test failure is signalled.  In addition if check_expected() is called and
no more parameter values are queued a test failure occurs.</p>

<h4>Using expect_*()</h4>
<a href="../example/product_database.c">product_database.c</a>
<listing>
#include &lt;database.h&gt;

// Connect to the database containing customer information.
DatabaseConnection* connect_to_product_database() {
    return connect_to_database("products.abcd.org", 322);
}
</listing>
<a href="../example/product_database_test.c">product_database_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;cmocka.h&gt;
#include &lt;database.h&gt;

extern DatabaseConnection* connect_to_product_database();

/* Mock connect to database function.
 * NOTE: This mock function is very general could be shared between tests
 * that use the imaginary database.h module. */
DatabaseConnection* connect_to_database(const char * const url,
                                        const unsigned int port) {
    check_expected(url);
    check_expected(port);
    return (DatabaseConnection*)mock();
}

void test_connect_to_product_database(void **state) {
    expect_string(connect_to_database, url, "products.abcd.org");
    expect_value(connect_to_database, port, 322);
    will_return(connect_to_database, 0xDA7ABA53);
    assert_int_equal(connect_to_product_database(), 0xDA7ABA53);
}

/* This test will fail since the expected URL is different to the URL that is
 * passed to connect_to_database() by connect_to_product_database(). */
void test_connect_to_product_database_bad_url(void **state) {
    expect_string(connect_to_database, url, "products.abcd.com");
    expect_value(connect_to_database, port, 322);
    will_return(connect_to_database, 0xDA7ABA53);
    assert_int_equal((int)connect_to_product_database(), 0xDA7ABA53);
}

/* This test will fail since the mock connect_to_database() will attempt to
 * retrieve a value for the parameter port which isn't specified by this
 * test function. */
void test_connect_to_product_database_missing_parameter(void **state) {
    expect_string(connect_to_database, url, "products.abcd.org");
    will_return(connect_to_database, 0xDA7ABA53);
    assert_int_equal((int)connect_to_product_database(), 0xDA7ABA53);
}

int main(int argc, char* argv[]) {
    const UnitTest tests[] = {
        unit_test(test_connect_to_product_database),
        unit_test(test_connect_to_product_database_bad_url),
        unit_test(test_connect_to_product_database_missing_parameter),
    };
    return run_tests(tests);
}
</listing>

<a name="Test_State"><h2>Test State</h2></a>

<p>cmocka allows the specification of multiple setup and tear down functions
for each test case.  Setup functions, specified by the <b>unit_test_setup()</b>
or <b>unit_test_setup_teardown()</b> macros allow common initialization to be
shared between multiple test cases.  In addition, tear down functions,
specified by the <b>unit_test_teardown()</b> or
<b>unit_test_setup_teardown()</b> macros provide a code path that is always
executed for a test case even when it fails.</p>

<h4>Using unit_test_setup_teardown()</h4>
<a href="../example/key_value.c">key_value.c</a>
<listing>
#include &lt;stddef.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;

typedef struct KeyValue {
    unsigned int key;
    const char* value;
} KeyValue;

static KeyValue *key_values = NULL;
static unsigned int number_of_key_values = 0;

void set_key_values(KeyValue * const new_key_values,
                    const unsigned int new_number_of_key_values) {
    key_values = new_key_values;
    number_of_key_values = new_number_of_key_values;
}

// Compare two key members of KeyValue structures.
int key_value_compare_keys(const void *a, const void *b) {
    return (int)((KeyValue*)a)->key - (int)((KeyValue*)b)->key;
}

// Search an array of key value pairs for the item with the specified value.
KeyValue* find_item_by_value(const char * const value) {
  unsigned int i;
    for (i = 0; i < number_of_key_values; i++) {
        if (strcmp(key_values[i].value, value) == 0) {
            return &key_values[i];
        }
    }
    return NULL;
}

// Sort an array of key value pairs by key.
void sort_items_by_key() {
    qsort(key_values, number_of_key_values, sizeof(*key_values),
          key_value_compare_keys);
}
</listing>
<a href="../example/key_value_test.c">key_value_test.c</a>
<listing>
#include &lt;stdarg.h&gt;
#include &lt;stddef.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;string.h&gt;
#include &lt;cmocka.h&gt;

/* This is duplicated here from the module setup_teardown.c to reduce the
 * number of files used in this test. */
typedef struct KeyValue {
    unsigned int key;
    const char* value;
} KeyValue;

void set_key_values(KeyValue * const new_key_values,
                    const unsigned int new_number_of_key_values);
extern KeyValue* find_item_by_value(const char * const value);
extern void sort_items_by_key();

static KeyValue key_values[] = {
    { 10, "this" },
    { 52, "test" },
    { 20, "a" },
    { 13, "is" },
};

void create_key_values(void **state) {
    KeyValue * const items = (KeyValue*)test_malloc(sizeof(key_values));
    memcpy(items, key_values, sizeof(key_values));
    *state = (void*)items;
    set_key_values(items, sizeof(key_values) / sizeof(key_values[0]));
}

void destroy_key_values(void **state) {
    test_free(*state);
    set_key_values(NULL, 0);
}

void test_find_item_by_value(void **state) {
    unsigned int i;
    for (i = 0; i < sizeof(key_values) / sizeof(key_values[0]); i++) {
        KeyValue * const found  = find_item_by_value(key_values[i].value);
        assert_true(found);
        assert_int_equal(found->key, key_values[i].key);
        assert_string_equal(found->value, key_values[i].value);
    }
}

void test_sort_items_by_key(void **state) {
    unsigned int i;
    KeyValue * const kv = *state;
    sort_items_by_key();
    for (i = 1; i < sizeof(key_values) / sizeof(key_values[0]); i++) {
        assert_true(kv[i - 1].key < kv[i].key);
    }
}

int main(int argc, char* argv[]) {
    const UnitTest tests[] = {
        unit_test_setup_teardown(test_find_item_by_value, create_key_values,
                                 destroy_key_values),
        unit_test_setup_teardown(test_sort_items_by_key, create_key_values,
                                 destroy_key_values),
    };
    return run_tests(tests);
}
</listing>

<a name="Example"><h2>Example</h2></a>

<p>A small command line calculator
<a href="../example/calculator.c">calculator.c</a> application
and test application that full exercises the calculator application
<a href="../example/calculator_test.c">calculator_test.c</a>
are provided as an example of cmocka's features discussed in this document.
</p>

<hr>
<address></address>
<!-- hhmts start --> Last modified: Wed Jul 22 12:11:43 PDT 2009 <!-- hhmts end -->
</body> </html>