xref: /linux/lib/kunit/kunit-example-test.c (revision 87c9c16317882dd6dbbc07e349bc3223e14f3244)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Example KUnit test to show how to use KUnit.
4  *
5  * Copyright (C) 2019, Google LLC.
6  * Author: Brendan Higgins <brendanhiggins@google.com>
7  */
8 
9 #include <kunit/test.h>
10 
11 /*
12  * This is the most fundamental element of KUnit, the test case. A test case
13  * makes a set EXPECTATIONs and ASSERTIONs about the behavior of some code; if
14  * any expectations or assertions are not met, the test fails; otherwise, the
15  * test passes.
16  *
17  * In KUnit, a test case is just a function with the signature
18  * `void (*)(struct kunit *)`. `struct kunit` is a context object that stores
19  * information about the current test.
20  */
21 static void example_simple_test(struct kunit *test)
22 {
23 	/*
24 	 * This is an EXPECTATION; it is how KUnit tests things. When you want
25 	 * to test a piece of code, you set some expectations about what the
26 	 * code should do. KUnit then runs the test and verifies that the code's
27 	 * behavior matched what was expected.
28 	 */
29 	KUNIT_EXPECT_EQ(test, 1 + 1, 2);
30 }
31 
32 /*
33  * This is run once before each test case, see the comment on
34  * example_test_suite for more information.
35  */
36 static int example_test_init(struct kunit *test)
37 {
38 	kunit_info(test, "initializing\n");
39 
40 	return 0;
41 }
42 
43 /*
44  * Here we make a list of all the test cases we want to add to the test suite
45  * below.
46  */
47 static struct kunit_case example_test_cases[] = {
48 	/*
49 	 * This is a helper to create a test case object from a test case
50 	 * function; its exact function is not important to understand how to
51 	 * use KUnit, just know that this is how you associate test cases with a
52 	 * test suite.
53 	 */
54 	KUNIT_CASE(example_simple_test),
55 	{}
56 };
57 
58 /*
59  * This defines a suite or grouping of tests.
60  *
61  * Test cases are defined as belonging to the suite by adding them to
62  * `kunit_cases`.
63  *
64  * Often it is desirable to run some function which will set up things which
65  * will be used by every test; this is accomplished with an `init` function
66  * which runs before each test case is invoked. Similarly, an `exit` function
67  * may be specified which runs after every test case and can be used to for
68  * cleanup. For clarity, running tests in a test suite would behave as follows:
69  *
70  * suite.init(test);
71  * suite.test_case[0](test);
72  * suite.exit(test);
73  * suite.init(test);
74  * suite.test_case[1](test);
75  * suite.exit(test);
76  * ...;
77  */
78 static struct kunit_suite example_test_suite = {
79 	.name = "example",
80 	.init = example_test_init,
81 	.test_cases = example_test_cases,
82 };
83 
84 /*
85  * This registers the above test suite telling KUnit that this is a suite of
86  * tests that need to be run.
87  */
88 kunit_test_suites(&example_test_suite);
89 
90 MODULE_LICENSE("GPL v2");
91