[PATCH 2/3] kunit: add ability to specify suite-level init and exit functions

[Daniel Latypov]

KUnit has support for setup/cleanup logic for each test case in a suite.
But it lacks the ability to specify setup/cleanup for the entire suite
itself.

This can be used to do setup that is too expensive or cumbersome to do
for each test.
Or it can be used to do simpler things like log debug information after
the suite completes.
It's a fairly common feature, so the lack of it is noticeable.

Some examples in other frameworks and languages:
* https://docs.python.org/3/library/unittest.html#setupclass-and-teardownclass
* https://google.github.io/googletest/reference/testing.html#Test::SetUpTestSuite

Meta:
This is very similar to this patch here: https://lore.kernel.org/linux-kselftest/20210805043503.20252-3-bvanassche@xxxxxxx/
The changes from that patch:
* pass in `struct kunit *` so users can do stuff like
  `kunit_info(suite, "debug message")`
* makes sure the init failure is bubbled up as a failure
* updates kunit-example-test.c to use a suite init
* Updates kunit/usage.rst to mention the new support
* some minor cosmetic things
  * use `suite_{init,exit}` instead of `{init/exit}_suite`
  * make suite init error message more consistent w/ test init
  * etc.

Signed-off-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
---
 Documentation/dev-tools/kunit/usage.rst | 19 +++++++++++--------
 include/kunit/test.h                    |  4 ++++
 lib/kunit/kunit-example-test.c          | 14 ++++++++++++++
 lib/kunit/test.c                        | 23 ++++++++++++++++++++---
 4 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst
index 1c83e7d60a8a..d62a04255c2e 100644
--- a/Documentation/dev-tools/kunit/usage.rst
+++ b/Documentation/dev-tools/kunit/usage.rst
@@ -125,8 +125,8 @@ We need many test cases covering all the unit's behaviors. It is common to have
 many similar tests. In order to reduce duplication in these closely related
 tests, most unit testing frameworks (including KUnit) provide the concept of a
 *test suite*. A test suite is a collection of test cases for a unit of code
-with a setup function that gets invoked before every test case and then a tear
-down function that gets invoked after every test case completes. For example:
+with optional setup and teardown functions that run before/after the whole
+suite and/or every test case. For example:
 
 .. code-block:: c
 
@@ -141,16 +141,19 @@ down function that gets invoked after every test case completes. For example:
 		.name = "example",
 		.init = example_test_init,
 		.exit = example_test_exit,
+		.suite_init = example_suite_init,
+		.suite_exit = example_suite_exit,
 		.test_cases = example_test_cases,
 	};
 	kunit_test_suite(example_test_suite);
 
-In the above example, the test suite ``example_test_suite`` would run the test
-cases ``example_test_foo``, ``example_test_bar``, and ``example_test_baz``. Each
-would have ``example_test_init`` called immediately before it and
-``example_test_exit`` called immediately after it.
-``kunit_test_suite(example_test_suite)`` registers the test suite with the
-KUnit test framework.
+In the above example, the test suite ``example_test_suite`` would first run
+``example_suite_init``, then run the test cases ``example_test_foo``,
+``example_test_bar``, and ``example_test_baz``. Each would have
+``example_test_init`` called immediately before it and ``example_test_exit``
+called immediately after it. Finally, ``example_suite_exit`` would be called
+after everything else. ``kunit_test_suite(example_test_suite)`` registers the
+test suite with the KUnit test framework.
 
 .. note::
    A test case will only run if it is associated with a test suite.
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 97cd76461886..5d288f3d8f68 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -153,6 +153,8 @@ static inline char *kunit_status_to_ok_not_ok(enum kunit_status status)
  * struct kunit_suite - describes a related collection of &struct kunit_case
  *
  * @name:	the name of the test. Purely informational.
+ * @suite_init:	called once per test suite before the test cases.
+ * @suite_exit:	called once per test suite after all test cases.
  * @init:	called before every test case.
  * @exit:	called after every test case.
  * @test_cases:	a null terminated array of test cases.
@@ -167,6 +169,8 @@ static inline char *kunit_status_to_ok_not_ok(enum kunit_status status)
  */
 struct kunit_suite {
 	const char name[256];
+	int (*suite_init)(struct kunit_suite *suite);
+	void (*suite_exit)(struct kunit_suite *suite);
 	int (*init)(struct kunit *test);
 	void (*exit)(struct kunit *test);
 	struct kunit_case *test_cases;
diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c
index 91b1df7f59ed..f8fe582c9e36 100644
--- a/lib/kunit/kunit-example-test.c
+++ b/lib/kunit/kunit-example-test.c
@@ -40,6 +40,17 @@ static int example_test_init(struct kunit *test)
 	return 0;
 }
 
+/*
+ * This is run once before all test cases in the suite.
+ * See the comment on example_test_suite for more information.
+ */
+static int example_test_init_suite(struct kunit_suite *suite)
+{
+	kunit_info(suite, "initializing suite\n");
+
+	return 0;
+}
+
 /*
  * This test should always be skipped.
  */
@@ -142,17 +153,20 @@ static struct kunit_case example_test_cases[] = {
  * may be specified which runs after every test case and can be used to for
  * cleanup. For clarity, running tests in a test suite would behave as follows:
  *
+ * suite.suite_init(suite);
  * suite.init(test);
  * suite.test_case[0](test);
  * suite.exit(test);
  * suite.init(test);
  * suite.test_case[1](test);
  * suite.exit(test);
+ * suite.suite_exit(suite);
  * ...;
  */
 static struct kunit_suite example_test_suite = {
 	.name = "example",
 	.init = example_test_init,
+	.suite_init = example_test_init_suite,
 	.test_cases = example_test_cases,
 };
 
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 64ee6a9d8003..b66e395c795a 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -192,10 +192,13 @@ EXPORT_SYMBOL_GPL(kunit_suite_has_succeeded);
 
 static size_t kunit_suite_counter = 1;
 
-static void kunit_print_suite_end(struct kunit_suite *suite)
+static void kunit_print_suite_end(struct kunit_suite *suite, int init_err)
 {
+	enum kunit_status status =
+		init_err ? KUNIT_FAILURE : kunit_suite_has_succeeded(suite);
+
 	kunit_print_ok_not_ok((void *)suite, false,
-			      kunit_suite_has_succeeded(suite),
+			      status,
 			      kunit_suite_counter++,
 			      suite->name,
 			      suite->status_comment);
@@ -497,6 +500,16 @@ int kunit_run_tests(struct kunit_suite *suite)
 	struct kunit_case *test_case;
 	struct kunit_result_stats suite_stats = { 0 };
 	struct kunit_result_stats total_stats = { 0 };
+	int suite_init_err = 0;
+
+	if (suite->suite_init) {
+		suite_init_err = suite->suite_init(suite);
+		if (suite_init_err != 0) {
+			kunit_err(suite, KUNIT_SUBTEST_INDENT
+				  "# failed to initialize (%d)", suite_init_err);
+			goto suite_end;
+		}
+	}
 
 	kunit_print_suite_start(suite);
 
@@ -551,8 +564,12 @@ int kunit_run_tests(struct kunit_suite *suite)
 		kunit_accumulate_stats(&total_stats, param_stats);
 	}
 
+	if (suite->suite_exit)
+		suite->suite_exit(suite);
+
 	kunit_print_suite_stats(suite, suite_stats, total_stats);
-	kunit_print_suite_end(suite);
+suite_end:
+	kunit_print_suite_end(suite, suite_init_err);
 
 	return 0;
 }
-- 
2.36.0.rc2.479.g8af0fa9b8e-goog