Documentation: kunit: Remove redundant 'tips.rst' page

The contents of 'tips.rst' was mostly included in 'usage.rst' way back in
commit 95357439 ("Documentation: KUnit: Rework writing page to focus on writing tests"),
but the tips page remained behind as well.

The parent patches in this series fill in the gaps, so now 'tips.rst' is
redundant.
Therefore, delete 'tips.rst'.

While I regret breaking any links to 'tips' which might exist
externally, it's confusing to have two subtly different versions of the
same content around.
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Sadiya Kazi <sadiyakazi@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Documentation/dev-tools/kunit/index.rst

@@ -16,7 +16,6 @@ KUnit - Linux Kernel Unit Testing
 	api/index
 	style
 	faq
-	tips
 	running_tips
 
 This section details the kernel unit testing framework.

Documentation/dev-tools/kunit/tips.rst

-.. SPDX-License-Identifier: GPL-2.0
-
-============================
-Tips For Writing KUnit Tests
-============================
-
-Exiting early on failed expectations
-------------------------------------
-
-``KUNIT_EXPECT_EQ`` and friends will mark the test as failed and continue
-execution.  In some cases, it's unsafe to continue and you can use the
-``KUNIT_ASSERT`` variant to exit on failure.
-
-.. code-block:: c
-
-	void example_test_user_alloc_function(struct kunit *test)
-	{
-		void *object = alloc_some_object_for_me();
-
-		/* Make sure we got a valid pointer back. */
-		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, object);
-		do_something_with_object(object);
-	}
-
-Allocating memory
------------------
-
-Where you would use ``kzalloc``, you should prefer ``kunit_kzalloc`` instead.
-KUnit will ensure the memory is freed once the test completes.
-
-This is particularly useful since it lets you use the ``KUNIT_ASSERT_EQ``
-macros to exit early from a test without having to worry about remembering to
-call ``kfree``.
-
-Example:
-
-.. code-block:: c
-
-	void example_test_allocation(struct kunit *test)
-	{
-		char *buffer = kunit_kzalloc(test, 16, GFP_KERNEL);
-		/* Ensure allocation succeeded. */
-		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buffer);
-
-		KUNIT_ASSERT_STREQ(test, buffer, "");
-	}
-
-
-Testing static functions
-------------------------
-
-If you don't want to expose functions or variables just for testing, one option
-is to conditionally ``#include`` the test file at the end of your .c file, e.g.
-
-.. code-block:: c
-
-	/* In my_file.c */
-
-	static int do_interesting_thing();
-
-	#ifdef CONFIG_MY_KUNIT_TEST
-	#include "my_kunit_test.c"
-	#endif
-
-Injecting test-only code
-------------------------
-
-Similarly to the above, it can be useful to add test-specific logic.
-
-.. code-block:: c
-
-	/* In my_file.h */
-
-	#ifdef CONFIG_MY_KUNIT_TEST
-	/* Defined in my_kunit_test.c */
-	void test_only_hook(void);
-	#else
-	void test_only_hook(void) { }
-	#endif
-
-This test-only code can be made more useful by accessing the current kunit
-test, see below.
-
-Accessing the current test
---------------------------
-
-In some cases, you need to call test-only code from outside the test file, e.g.
-like in the example above or if you're providing a fake implementation of an
-ops struct.
-There is a ``kunit_test`` field in ``task_struct``, so you can access it via
-``current->kunit_test``.
-
-Here's a slightly in-depth example of how one could implement "mocking":
-
-.. code-block:: c
-
-	#include <linux/sched.h> /* for current */
-
-	struct test_data {
-		int foo_result;
-		int want_foo_called_with;
-	};
-
-	static int fake_foo(int arg)
-	{
-		struct kunit *test = current->kunit_test;
-		struct test_data *test_data = test->priv;
-
-		KUNIT_EXPECT_EQ(test, test_data->want_foo_called_with, arg);
-		return test_data->foo_result;
-	}
-
-	static void example_simple_test(struct kunit *test)
-	{
-		/* Assume priv is allocated in the suite's .init */
-		struct test_data *test_data = test->priv;
-
-		test_data->foo_result = 42;
-		test_data->want_foo_called_with = 1;
-
-		/* In a real test, we'd probably pass a pointer to fake_foo somewhere
-		 * like an ops struct, etc. instead of calling it directly. */
-		KUNIT_EXPECT_EQ(test, fake_foo(1), 42);
-	}
-
-
-Note: here we're able to get away with using ``test->priv``, but if you wanted
-something more flexible you could use a named ``kunit_resource``, see
-Documentation/dev-tools/kunit/api/test.rst.
-
-Failing the current test
-------------------------
-
-But sometimes, you might just want to fail the current test. In that case, we
-have ``kunit_fail_current_test(fmt, args...)`` which is defined in ``<kunit/test-bug.h>`` and
-doesn't require pulling in ``<kunit/test.h>``.
-
-E.g. say we had an option to enable some extra debug checks on some data structure:
-
-.. code-block:: c
-
-	#include <kunit/test-bug.h>
-
-	#ifdef CONFIG_EXTRA_DEBUG_CHECKS
-	static void validate_my_data(struct data *data)
-	{
-		if (is_valid(data))
-			return;
-
-		kunit_fail_current_test("data %p is invalid", data);
-
-		/* Normal, non-KUnit, error reporting code here. */
-	}
-	#else
-	static void my_debug_function(void) { }
-	#endif
-
-
-Customizing error messages
---------------------------
-
-Each of the ``KUNIT_EXPECT`` and ``KUNIT_ASSERT`` macros have a ``_MSG`` variant.
-These take a format string and arguments to provide additional context to the automatically generated error messages.
-
-.. code-block:: c
-
-	char some_str[41];
-	generate_sha1_hex_string(some_str);
-
-	/* Before. Not easy to tell why the test failed. */
-	KUNIT_EXPECT_EQ(test, strlen(some_str), 40);
-
-	/* After. Now we see the offending string. */
-	KUNIT_EXPECT_EQ_MSG(test, strlen(some_str), 40, "some_str='%s'", some_str);
-
-Alternatively, one can take full control over the error message by using ``KUNIT_FAIL()``, e.g.
-
-.. code-block:: c
-
-	/* Before */
-	KUNIT_EXPECT_EQ(test, some_setup_function(), 0);
-
-	/* After: full control over the failure message. */
-	if (some_setup_function())
-		KUNIT_FAIL(test, "Failed to setup thing for testing");
-
-Next Steps
-==========
-*   Optional: see the Documentation/dev-tools/kunit/usage.rst page for a more
-    in-depth explanation of KUnit.