Re: [PATCH v2 1/2] kunit: Support for Parameterized Testing

From: Arpitha Raghunandan <98.arpi@gmail.com>
To: Marco Elver <elver@google.com>
Cc: brendanhiggins@google.com, skhan@linuxfoundation.org,
	yzaikin@google.com, tytso@mit.edu, adilger.kernel@dilger.ca,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	linux-ext4@vger.kernel.org
Subject: Re: [PATCH v2 1/2] kunit: Support for Parameterized Testing
Date: Sat, 24 Oct 2020 10:53:51 +0530	[thread overview]
Message-ID: <91906d36-1f5b-b388-42a7-881b0915f0ea@gmail.com> (raw)
In-Reply-To: <20201023184803.GA3922681@elver.google.com>

On 24/10/20 12:18 am, Marco Elver wrote:
> On Fri, Oct 23, 2020 at 08:35PM +0530, Arpitha Raghunandan wrote:
>> Implementation of support for parameterized testing in KUnit.
> 
> Already looks much cleaner, thanks for using this approach!
> 
> I think the commit message needs a brief summary of the approach.
> 

Okay, I will add a more detailed commit message for the next version.

>> Signed-off-by: Arpitha Raghunandan <98.arpi@gmail.com>
>> ---
>> Changes v1->v2:
>> - Use of a generator method to access test case parameters
>>
>>  include/kunit/test.h | 45 ++++++++++++++++++++++++++++++++++++++++++++
>>  lib/kunit/test.c     | 20 +++++++++++++++++++-
>>  2 files changed, 64 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/kunit/test.h b/include/kunit/test.h
>> index a423fffefea0..c417ac140326 100644
>> --- a/include/kunit/test.h
>> +++ b/include/kunit/test.h
>> @@ -141,6 +141,7 @@ struct kunit;
>>  struct kunit_case {
>>  	void (*run_case)(struct kunit *test);
>>  	const char *name;
>> +	void* (*generate_params)(struct kunit *test, void *prev);
> 
> Would adding documentation above this field be the right place, or
> somewhere else? In any case, some explanation of the protocol would be
> good.
> 

I will include this.

>>  	/* private: internal use only. */
>>  	bool success;
>> @@ -162,6 +163,9 @@ static inline char *kunit_status_to_string(bool status)
>>   * &struct kunit_case for an example on how to use it.
>>   */
>>  #define KUNIT_CASE(test_name) { .run_case = test_name, .name = #test_name }
>> +#define KUNIT_CASE_PARAM(test_name, gen_params)			\
>> +		{ .run_case = test_name, .name = #test_name,	\
>> +		  .generate_params = gen_params }
>>  
>>  /**
>>   * struct kunit_suite - describes a related collection of &struct kunit_case
>> @@ -208,6 +212,15 @@ struct kunit {
>>  	const char *name; /* Read only after initialization! */
>>  	char *log; /* Points at case log after initialization */
>>  	struct kunit_try_catch try_catch;
>> +	/* param_values points to test case parameters in parameterized tests */
>> +	void *param_values;
>> +	/*
>> +	 * current_param stores the index of the parameter in
>> +	 * the array of parameters in parameterized tests.
>> +	 * current_param + 1 is printed to indicate the parameter
>> +	 * that causes the test to fail in case of test failure.
>> +	 */
>> +	int current_param;
>>  	/*
>>  	 * success starts as true, and may only be set to false during a
>>  	 * test case; thus, it is safe to update this across multiple
>> @@ -1742,4 +1755,36 @@ do {									       \
>>  						fmt,			       \
>>  						##__VA_ARGS__)
>>  
>> +/**
>> + * kunit_param_generator_helper() - Helper method for test parameter generators
>> + * 				    required in parameterized tests.
>> + * @test: The test context object.
>> + * @prev_param: a pointer to the previous test parameter, NULL for first parameter.
>> + * @param_array: a user-supplied pointer to an array of test parameters.
>> + * @array_size: number of test parameters in the array.
>> + * @type_size: size of one test parameter.
>> + */
>> +static inline void *kunit_param_generator_helper(struct kunit *test,
> 
> I don't think this needs to be inline, but see my other suggestion
> below, which might make this function obsolete.
> 
>> +					void *prev_param,
>> +					void *param_array,
>> +					size_t array_size,
>> +					size_t type_size)
>> +{
>> +	KUNIT_ASSERT_EQ(test, (prev_param - param_array) % type_size, 0);
>> +
>> +	if (!prev_param)
>> +		return param_array;
>> +
>> +	KUNIT_ASSERT_GE(test, prev_param, param_array);
>> +
>> +	if (prev_param + type_size < param_array + (array_size * type_size))
>> +		return prev_param + type_size;
>> +	else
>> +		return NULL;
>> +}
>> +
>> +#define KUNIT_PARAM_GENERATOR_HELPER(test, prev_param, param_array, param_type) \
>> +	kunit_param_generator_helper(test, prev_param, param_array,		\
>> +				ARRAY_SIZE(param_array), sizeof(param_type))
> 
> You do not need param_type, you can use the same trick that ARRAY_SIZE
> uses:
> 
> 	#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
> 
> So you could use sizeof((param_aray)[0]) instead of sizeof(param_type).
> ARRAY_SIZE already checks for you that it's a real array via
> __must_be_array().
> 
> 
> The other question is, will kunit_param_generator_helper() find much use
> without the KUNIT_PARAM_GENERATOR_HELPER() macro? If I have some
> complicated generator protocol to generate params, then I'd just
> directly write the generator function. If your intent is to simplify the
> common-case array based generators, why not just have a macro generate
> the generator function?
> 
> More specifically, have this macro here:
> 
> +#define KUNIT_ARRAY_PARAM(name, array)								\
> +	static void *name##_gen_params(struct kunit *test, void *prev)				\
> +	{											\
> +		typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);	\
> +		return __next - (array) < ARRAY_SIZE((array)) ? __next : NULL;			\
> +	}
> 
> [ It is entirely untested, but if it works verbatim you'll probably need my
> 
> 	Co-developed-by: Marco Elver <elver@google.com>
> 	Signed-off-by: Marco Elver <elver@google.com>
>  
>  just in case... ]
> 
> Then, it can be used as follows:
> 
> 	static int num_cpus[] = {1, 2, 3, 4, 5};
> 	KUNIT_ARRAY_PARAM(num_cpus, num_cpus);
> 
> Then somewhere else:
> 
> 	KUNIT_CASE_PARAM(some_test, num_cpus_gen_params);
> 

Yes, a macro can be used to generate the generator function. I will work with this
for the next version.

>>  #endif /* _KUNIT_TEST_H */
>> diff --git a/lib/kunit/test.c b/lib/kunit/test.c
>> index 750704abe89a..0e6ffe6384a7 100644
>> --- a/lib/kunit/test.c
>> +++ b/lib/kunit/test.c
>> @@ -127,6 +127,11 @@ unsigned int kunit_test_case_num(struct kunit_suite *suite,
>>  }
>>  EXPORT_SYMBOL_GPL(kunit_test_case_num);
>>  
>> +static void kunit_print_failed_param(struct kunit *test)
>> +{
>> +	kunit_err(test, "\n\tTest failed at parameter: %d\n", test->current_param + 1);
>> +}
>> +
>>  static void kunit_print_string_stream(struct kunit *test,
>>  				      struct string_stream *stream)
>>  {
>> @@ -168,6 +173,8 @@ static void kunit_fail(struct kunit *test, struct kunit_assert *assert)
>>  	assert->format(assert, stream);
>>  
>>  	kunit_print_string_stream(test, stream);
>> +	if (test->param_values)
>> +		kunit_print_failed_param(test);
>>  
>>  	WARN_ON(string_stream_destroy(stream));
>>  }
>> @@ -239,7 +246,18 @@ static void kunit_run_case_internal(struct kunit *test,
>>  		}
>>  	}
>>  
>> -	test_case->run_case(test);
>> +	if (!test_case->generate_params) {
>> +		test_case->run_case(test);
>> +	} else {
>> +		test->param_values = test_case->generate_params(test, NULL);
>> +		test->current_param = 0;
>> +
>> +		while (test->param_values) {
>> +			test_case->run_case(test);
>> +			test->param_values = test_case->generate_params(test, test->param_values);
>> +			test->current_param++;
>> +		}
>> +	}
>>  }
>>  
>>  static void kunit_case_internal_cleanup(struct kunit *test)
> 
> Otherwise looks fine.
> 
> Thanks,
> -- Marco
> 

Thanks!