[RFC,v1,3/6] kunit: Add ability to filter attributes

Add filtering of test attributes. Users can filter tests using a
module_param_array called "filter". This functionality will be added to
kunit.py in the next patch.

The filters will be imputed in the format:
"<attribute_name><operation><attribute_value>"

Example: "speed>slow"

Operations include: >, <, >=, <=, !=, and =. These operations do not need
to act the same for every attribute.

Add method to parse inputted filters.

Add the process of filtering tests based on attributes. The process of
filtering follows these rules:

A test case with a set attribute overrides its parent suite's attribute
during filtering.

Also, if both the test case attribute and suite attribute are unset the
test acts as the default attribute value during filtering.

Finally, add a "filter" method for the speed attribute to parse and compare
enum values of kunit_speed.

Signed-off-by: Rae Moar <rmoar@google.com>
---
 include/kunit/attributes.h |  22 +++++
 lib/kunit/attributes.c     | 172 +++++++++++++++++++++++++++++++++++++
 lib/kunit/executor.c       |  79 +++++++++++++----
 lib/kunit/executor_test.c  |   8 +-
 4 files changed, 258 insertions(+), 23 deletions(-)

On Sat, Jun 10, 2023 at 12:51:46AM +0000, Rae Moar wrote:
> Add filtering of test attributes. Users can filter tests using a
> module_param_array called "filter". This functionality will be added to
> kunit.py in the next patch.
> 
> The filters will be imputed in the format:
> "<attribute_name><operation><attribute_value>"
> 
> Example: "speed>slow"
> 
> Operations include: >, <, >=, <=, !=, and =. These operations do not need
> to act the same for every attribute.

How is the "default" filter specified? Is explicitly unfiltered? (i.e.
"slow" stuff will run by default?) Or should there be a default filter
of "speed<slow" for the memcpy conversion?

But yes, I'm a fan of this whole series! I would much prefer this to
having one-off CONFIGs for slow tests. :)

On Sat, Jun 10, 2023 at 4:29 AM David Gow <davidgow@google.com> wrote:
>
> On Sat, 10 Jun 2023 at 08:52, Rae Moar <rmoar@google.com> wrote:
> >
> > Add filtering of test attributes. Users can filter tests using a
> > module_param_array called "filter". This functionality will be added to
> > kunit.py in the next patch.
> >
> > The filters will be imputed in the format:
> > "<attribute_name><operation><attribute_value>"
> >
> > Example: "speed>slow"
>
> Maybe give a full command-line example of "kunit.filter=speed>slow"?
>

Hello,

Yes I will add that in the next version.

> >
> > Operations include: >, <, >=, <=, !=, and =. These operations do not need
> > to act the same for every attribute.
>
> I assume here that operations should act the same for attributes of
> the same type, but a string attribute might behave differently from an
> int, an enum, an array, etc.
>
> As a design principle, I think we definitely want the same operation
> to act the same way between different attributes, unless there's an
> extraordinarily good reason.
>

This is a mistake on my end. I should clarify that operations should
act the same for attributes of the same type but then may differ
between the types (like ints and strings).

> >
> > Add method to parse inputted filters.
> >
> > Add the process of filtering tests based on attributes. The process of
> > filtering follows these rules:
> >
> > A test case with a set attribute overrides its parent suite's attribute
> > during filtering.
> >
> > Also, if both the test case attribute and suite attribute are unset the
> > test acts as the default attribute value during filtering.
>
> This behaviour probably needs to be documented more clearly in the
> final version.
>
> As I understand it:
> - Both tests and suites have attributes.
> - Filtering always operates at a per-test level.
> - If a test has an attribute set, then the test's value is filtered on.
> - Otherwise, the value falls back to the suite's value.
> - If neither are set, the attribute has a global "default" value, which is used.
> - If an entire suite is filtered out, it's removed, giving the
> appearance that filtering can operate on a suite level.
>

Yes, this is a great description of how it should behave. I will be
more explicit in my description for the next version.

> I actually quite like these rules, but we do need to document them.
> I'd perhaps argue that the "default attribute" could be done away with
> and we just rely on the filter function choosing whether or not
> "unset" matches a filter or not, but on the other hand, it does make
> reusing filter functions potentially easier.
>

This is true I could do away with the default. However, I do think it
helps to document how an unset attribute acts.

It may seem more unclear why an unset attribute is filtered out for
speed<=slow but not speed>slow. But this could then be documented
separate from the code.

I'm leaning toward keeping it but let me know what you think.

> >
> > Finally, add a "filter" method for the speed attribute to parse and compare
> > enum values of kunit_speed.
> >
> > Signed-off-by: Rae Moar <rmoar@google.com>
> > ---
>
> One other idea: do we want filtered-out tests to totally disappear (as
> this patch does), to mark them as skipped (potentially useful, too),
> or have configurable behaviour.
>
> I think there are good reasons for each of those: having them totally
> disappear is much cleaner, but it's also useful to see what tests
> you're actually, well, skipping.

I like this idea a lot. I also really like the idea of this being a
configurable behavior.

>
> >  include/kunit/attributes.h |  22 +++++
> >  lib/kunit/attributes.c     | 172 +++++++++++++++++++++++++++++++++++++
> >  lib/kunit/executor.c       |  79 +++++++++++++----
> >  lib/kunit/executor_test.c  |   8 +-
> >  4 files changed, 258 insertions(+), 23 deletions(-)
> >
> > diff --git a/include/kunit/attributes.h b/include/kunit/attributes.h
> > index 9fcd184cce36..bca60d1181bb 100644
> > --- a/include/kunit/attributes.h
> > +++ b/include/kunit/attributes.h
> > @@ -9,6 +9,15 @@
> >  #ifndef _KUNIT_ATTRIBUTES_H
> >  #define _KUNIT_ATTRIBUTES_H
> >
> > +/*
> > + * struct kunit_attr_filter - representation of attributes filter with the
> > + * attribute object and string input
> > + */
> > +struct kunit_attr_filter {
> > +       struct kunit_attr *attr;
> > +       char *input;
> > +};
> > +
> >  /*
> >   * Print all test attributes for a test case or suite.
> >   * Output format for test cases: "# <test_name>.<attribute>: <value>"
> > @@ -16,4 +25,17 @@
> >   */
> >  void kunit_print_attr(void *test_or_suite, bool is_test, unsigned int test_level);
> >
> > +/*
> > + * Parse attributes filter input and return an object containing the attribute
> > + * object and the string input.
> > + */
> > +struct kunit_attr_filter kunit_parse_filter_attr(char *input, int *err);
>
> Should we rename this kunit_parse_attr_filter, as it returns a
> kunit_attr_filter?
>

I will change this. I think that is cleaner.

> > +
> > +
> > +/*
> > + * Returns a copy of the suite containing only tests that pass the filter.
> > + */
> > +struct kunit_suite *kunit_filter_attr_tests(const struct kunit_suite *const suite,
> > +               struct kunit_attr_filter filter, int *err);
> > +
> >  #endif /* _KUNIT_ATTRIBUTES_H */
> > diff --git a/lib/kunit/attributes.c b/lib/kunit/attributes.c
> > index e17889f94693..4f753a28e4ee 100644
> > --- a/lib/kunit/attributes.c
> > +++ b/lib/kunit/attributes.c
> > @@ -49,6 +49,66 @@ static const char *attr_speed_to_string(void *attr, bool *to_free)
> >         return attr_enum_to_string(attr, speed_str_list, to_free);
> >  }
> >
> > +/* Filter Methods */
> > +
> > +static int int_filter(long val, const char *op, int input, int *err)
> > +{
> > +       if (!strncmp(op, "<=", 2))
> > +               return (val <= input);
> > +       else if (!strncmp(op, ">=", 2))
> > +               return (val >= input);
> > +       else if (!strncmp(op, "!=", 2))
> > +               return (val != input);
> > +       else if (!strncmp(op, ">", 1))
> > +               return (val > input);
> > +       else if (!strncmp(op, "<", 1))
> > +               return (val < input);
> > +       else if (!strncmp(op, "=", 1))
> > +               return (val == input);
> > +       *err = -EINVAL;
> > +       pr_err("kunit executor: invalid filter operation: %s\n", op);
> > +       return false;
> > +}
> > +
> > +static int attr_enum_filter(void *attr, const char *input, int *err,
> > +               const char * const str_list[], int max)
>
> As this is a generic helper function to be used by multiple types of
> attributes, let's document it a bit.

Sounds great. I will add documentation here.

>
> > +{
> > +       int i, j, input_int;
> > +       long test_val = (long)attr;
> > +       const char *input_val;
> > +
> > +       for (i = 0; input[i]; i++) {
> > +               if (!strchr("<!=>", input[i])) {
>
> Can we yoink this string of "operation characters" into a global or
> #define or something, as it recurs a few times here, and it'd be best
> to only have it in one place.

Right, that sounds good. I will change this.

>
> > +                       input_val = input + i;
> > +                       break;
> > +               }
> > +       }
> > +
> > +       if (!input_val) {
> > +               *err = -EINVAL;
> > +               pr_err("kunit executor: filter operation not found: %s\n", input);
> > +               return false;
> > +       }
> > +
> > +       for (j = 0; j <= max; j++) {
> > +               if (!strcmp(input_val, str_list[j]))
> > +                       input_int = j;
> > +       }
> > +
> > +       if (!input_int) {
> > +               *err = -EINVAL;
> > +               pr_err("kunit executor: invalid filter input: %s\n", input);
> > +               return false;
> > +       }
> > +
> > +       return int_filter(test_val, input, input_int, err);
> > +}
> > +
> > +static int attr_speed_filter(void *attr, const char *input, int *err)
> > +{
> > +       return attr_enum_filter(attr, input, err, speed_str_list, KUNIT_SPEED_MAX);
> > +}
> > +
> >  /* Get Attribute Methods */
> >
> >  static void *attr_speed_get(void *test_or_suite, bool is_test)
> > @@ -68,6 +128,7 @@ static const struct kunit_attr speed_attr = {
> >         .name = "speed",
> >         .get_attr = attr_speed_get,
> >         .to_string = attr_speed_to_string,
> > +       .filter = attr_speed_filter,
> >         .attr_default = (void *)KUNIT_SPEED_NORMAL,
> >  };
> >
> > @@ -106,3 +167,114 @@ void kunit_print_attr(void *test_or_suite, bool is_test, unsigned int test_level
> >                 }
> >         }
> >  }
> > +
> > +/* Helper Functions to Filter Attributes */
> > +
> > +struct kunit_attr_filter kunit_parse_filter_attr(char *input, int *err)
> > +{
> > +       struct kunit_attr_filter filter;
> > +       int i, j, op_index = 0;
> > +       int attr_index = -1;
> > +       char op;
> > +
> > +       /* Parse input until operation */
> > +       for (i = 0; input[i]; i++) {
> > +               if (strchr("<>!=", input[i])) {
> > +                       op_index = i;
> > +                       break;
> > +               }
> > +               if (input[i] == ' ')
> > +                       break;
> > +       }
> > +
> > +       if (!op_index) {
> > +               *err = -EINVAL;
> > +               pr_err("kunit executor: filter operation not found: %s\n", input);
> > +               return filter;
> > +       }
> > +
> > +       op = input[op_index];
> > +       input[op_index] = '\0';
> > +
> > +       /* Find associated kunit_attr object */
> > +       for (j = 0; j < ARRAY_SIZE(kunit_attr_list); j++) {
> > +               if (!strcmp(input, kunit_attr_list[j].name)) {
> > +                       attr_index = j;
> > +                       break;
> > +               }
> > +       }
> > +
> > +       input[op_index] = op;
> > +       filter.input = input + op_index;
> > +
> > +       if (attr_index < 0) {
> > +               *err = -EINVAL;
> > +               pr_err("kunit executor: attribute not found: %s\n", input);
> > +       } else {
> > +               filter.attr = &kunit_attr_list[attr_index];
> > +       }
> > +
> > +       return filter;
> > +}
> > +
> > +struct kunit_suite *kunit_filter_attr_tests(const struct kunit_suite *const suite,
> > +               struct kunit_attr_filter filter, int *err)
> > +{
> > +       int n = 0;
> > +       struct kunit_case *filtered, *test_case;
> > +       struct kunit_suite *copy;
> > +       void *suite_val, *test_val;
> > +       bool suite_result, test_result, default_result;
> > +
> > +       /* Allocate memory for new copy of suite and list of test cases */
> > +       copy = kmemdup(suite, sizeof(*copy), GFP_KERNEL);
> > +       if (!copy)
> > +               return ERR_PTR(-ENOMEM);
> > +
> > +       kunit_suite_for_each_test_case(suite, test_case) { n++; }
> > +
> > +       filtered = kcalloc(n + 1, sizeof(*filtered), GFP_KERNEL);
> > +       if (!filtered) {
> > +               kfree(copy);
> > +               return ERR_PTR(-ENOMEM);
> > +       }
> > +
> > +       n = 0;
> > +
> > +       /* Save filtering result on default value */
> > +       default_result = filter.attr->filter(filter.attr->attr_default, filter.input, err);
> > +
> > +       /* Save suite attribute value and filtering result on that value */
> > +       suite_val = filter.attr->get_attr((void *)suite, false);
> > +       suite_result = filter.attr->filter(suite_val, filter.input, err);
> > +
> > +       /* For each test case, save test case if passes filtering. */
> > +       kunit_suite_for_each_test_case(suite, test_case) {
> > +               test_val = filter.attr->get_attr((void *) test_case, true);
> > +               test_result = filter.attr->filter(filter.attr->get_attr(test_case, true),
> > +                               filter.input, err);
> > +               /*
> > +                * If attribute value of test case is set, filter on that value.
> > +                * If not, filter on suite value if set. If not, filter on
> > +                * default value.
> > +                */
> > +               if (test_val) {
> > +                       if (test_result)
> > +                               filtered[n++] = *test_case;
> > +               } else if (suite_val) {
> > +                       if (suite_result)
> > +                               filtered[n++] = *test_case;
> > +               } else if (default_result) {
> > +                       filtered[n++] = *test_case;
> > +               }
> > +       }
> > +
> > +       if (n == 0) {
> > +               kfree(copy);
> > +               kfree(filtered);
> > +               return NULL;
> > +       }
> > +
> > +       copy->test_cases = filtered;
> > +       return copy;
> > +}
> > diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
> > index 767a84e32f06..c67657821eec 100644
> > --- a/lib/kunit/executor.c
> > +++ b/lib/kunit/executor.c
> > @@ -15,8 +15,12 @@ extern struct kunit_suite * const __kunit_suites_end[];
> >
> >  #if IS_BUILTIN(CONFIG_KUNIT)
> >
> > +#define MAX_FILTERS 10 // Limit of number of attribute filters
> >  static char *filter_glob_param;
> >  static char *action_param;
> > +static int filter_count;
> > +static char *filter_param[MAX_FILTERS];
> > +
> >
> >  module_param_named(filter_glob, filter_glob_param, charp, 0);
> >  MODULE_PARM_DESC(filter_glob,
> > @@ -26,15 +30,16 @@ MODULE_PARM_DESC(action,
> >                  "Changes KUnit executor behavior, valid values are:\n"
> >                  "<none>: run the tests like normal\n"
> >                  "'list' to list test names instead of running them.\n");
> > +module_param_array_named(filter, filter_param, charp, &filter_count, 0);
> >
> >  /* glob_match() needs NULL terminated strings, so we need a copy of filter_glob_param. */
> > -struct kunit_test_filter {
> > +struct kunit_glob_filter {
> >         char *suite_glob;
> >         char *test_glob;
> >  };
> >
> >  /* Split "suite_glob.test_glob" into two. Assumes filter_glob is not empty. */
> > -static void kunit_parse_filter_glob(struct kunit_test_filter *parsed,
> > +static void kunit_parse_filter_glob(struct kunit_glob_filter *parsed,
> >                                     const char *filter_glob)
> >  {
> >         const int len = strlen(filter_glob);
> > @@ -56,7 +61,7 @@ static void kunit_parse_filter_glob(struct kunit_test_filter *parsed,
> >
> >  /* Create a copy of suite with only tests that match test_glob. */
> >  static struct kunit_suite *
> > -kunit_filter_tests(const struct kunit_suite *const suite, const char *test_glob)
> > +kunit_filter_glob_tests(const struct kunit_suite *const suite, const char *test_glob)
> >  {
> >         int n = 0;
> >         struct kunit_case *filtered, *test_case;
> > @@ -110,12 +115,15 @@ static void kunit_free_suite_set(struct suite_set suite_set)
> >
> >  static struct suite_set kunit_filter_suites(const struct suite_set *suite_set,
> >                                             const char *filter_glob,
> > +                                               char **filters,
> > +                                               int filter_count,
> >                                             int *err)
> >  {
> > -       int i;
> > -       struct kunit_suite **copy, *filtered_suite;
> > +       int i, j, k;
> > +       struct kunit_suite **copy, *filtered_suite, *new_filtered_suite;
> >         struct suite_set filtered;
> > -       struct kunit_test_filter filter;
> > +       struct kunit_glob_filter parsed_glob;
> > +       struct kunit_attr_filter parsed_filters[MAX_FILTERS];
> >
> >         const size_t max = suite_set->end - suite_set->start;
> >
> > @@ -126,17 +134,49 @@ static struct suite_set kunit_filter_suites(const struct suite_set *suite_set,
> >                 return filtered;
> >         }
> >
> > -       kunit_parse_filter_glob(&filter, filter_glob);
> > +       if (filter_glob)
> > +               kunit_parse_filter_glob(&parsed_glob, filter_glob);
> >
> > -       for (i = 0; &suite_set->start[i] != suite_set->end; i++) {
> > -               if (!glob_match(filter.suite_glob, suite_set->start[i]->name))
> > -                       continue;
> > +       /* Parse attribute filters */
> > +       if (filter_count) {
> > +               for (j = 0; j < filter_count; j++) {
> > +                       parsed_filters[j] = kunit_parse_filter_attr(filters[j], err);
> > +                       if (*err)
> > +                               return filtered;
> > +               }
> > +       }
> >
> > -               filtered_suite = kunit_filter_tests(suite_set->start[i], filter.test_glob);
> > -               if (IS_ERR(filtered_suite)) {
> > -                       *err = PTR_ERR(filtered_suite);
> > -                       return filtered;
> > +       for (i = 0; &suite_set->start[i] != suite_set->end; i++) {
> > +               filtered_suite = suite_set->start[i];
> > +               if (filter_glob) {
> > +                       if (!glob_match(parsed_glob.suite_glob, filtered_suite->name))
> > +                               continue;
> > +                       filtered_suite = kunit_filter_glob_tests(filtered_suite,
> > +                                       parsed_glob.test_glob);
> > +                       if (IS_ERR(filtered_suite)) {
> > +                               *err = PTR_ERR(filtered_suite);
> > +                               return filtered;
> > +                       }
> >                 }
> > +               if (filter_count) {
> > +                       for (k = 0; k < filter_count; k++) {
> > +                               new_filtered_suite = kunit_filter_attr_tests(filtered_suite,
> > +                                               parsed_filters[k], err);
> > +
> > +                               /* Free previous copy of suite */
> > +                               if (k > 0 || filter_glob)
> > +                                       kfree(filtered_suite);
> > +                               filtered_suite = new_filtered_suite;
> > +
> > +                               if (*err)
> > +                                       return filtered;
> > +                               if (IS_ERR(filtered_suite)) {
> > +                                       *err = PTR_ERR(filtered_suite);
> > +                                       return filtered;
> > +                               }
> > +                       }
> > +               }
> > +
> >                 if (!filtered_suite)
> >                         continue;
> >
> > @@ -144,8 +184,8 @@ static struct suite_set kunit_filter_suites(const struct suite_set *suite_set,
> >         }
> >         filtered.end = copy;
> >
> > -       kfree(filter.suite_glob);
> > -       kfree(filter.test_glob);
> > +       kfree(parsed_glob.suite_glob);
> > +       kfree(parsed_glob.test_glob);
> >         return filtered;
> >  }
> >
> > @@ -203,8 +243,9 @@ int kunit_run_all_tests(void)
> >                 goto out;
> >         }
> >
> > -       if (filter_glob_param) {
> > -               suite_set = kunit_filter_suites(&suite_set, filter_glob_param, &err);
> > +       if (filter_glob_param || filter_count) {
> > +               suite_set = kunit_filter_suites(&suite_set, filter_glob_param,
> > +                               filter_param, filter_count, &err);
> >                 if (err) {
> >                         pr_err("kunit executor: error filtering suites: %d\n", err);
> >                         goto out;
> > @@ -218,7 +259,7 @@ int kunit_run_all_tests(void)
> >         else
> >                 pr_err("kunit executor: unknown action '%s'\n", action_param);
> >
> > -       if (filter_glob_param) { /* a copy was made of each suite */
> > +       if (filter_glob_param || filter_count) { /* a copy was made of each suite */
> >                 kunit_free_suite_set(suite_set);
> >         }
> >
> > diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
> > index ce6749af374d..4c8cb46857b2 100644
> > --- a/lib/kunit/executor_test.c
> > +++ b/lib/kunit/executor_test.c
> > @@ -24,7 +24,7 @@ static struct kunit_case dummy_test_cases[] = {
> >
> >  static void parse_filter_test(struct kunit *test)
> >  {
> > -       struct kunit_test_filter filter = {NULL, NULL};
> > +       struct kunit_glob_filter filter = {NULL, NULL};
> >
> >         kunit_parse_filter_glob(&filter, "suite");
> >         KUNIT_EXPECT_STREQ(test, filter.suite_glob, "suite");
> > @@ -50,7 +50,7 @@ static void filter_suites_test(struct kunit *test)
> >         subsuite[1] = alloc_fake_suite(test, "suite2", dummy_test_cases);
> >
> >         /* Want: suite1, suite2, NULL -> suite2, NULL */
> > -       got = kunit_filter_suites(&suite_set, "suite2", &err);
> > +       got = kunit_filter_suites(&suite_set, "suite2", NULL, 0, &err);
> >         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
> >         KUNIT_ASSERT_EQ(test, err, 0);
> >         kfree_at_end(test, got.start);
> > @@ -74,7 +74,7 @@ static void filter_suites_test_glob_test(struct kunit *test)
> >         subsuite[1] = alloc_fake_suite(test, "suite2", dummy_test_cases);
> >
> >         /* Want: suite1, suite2, NULL -> suite2 (just test1), NULL */
> > -       got = kunit_filter_suites(&suite_set, "suite2.test2", &err);
> > +       got = kunit_filter_suites(&suite_set, "suite2.test2", NULL, 0, &err);
> >         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, got.start);
> >         KUNIT_ASSERT_EQ(test, err, 0);
> >         kfree_at_end(test, got.start);
> > @@ -100,7 +100,7 @@ static void filter_suites_to_empty_test(struct kunit *test)
> >         subsuite[0] = alloc_fake_suite(test, "suite1", dummy_test_cases);
> >         subsuite[1] = alloc_fake_suite(test, "suite2", dummy_test_cases);
> >
> > -       got = kunit_filter_suites(&suite_set, "not_found", &err);
> > +       got = kunit_filter_suites(&suite_set, "not_found", NULL, 0, &err);
> >         KUNIT_ASSERT_EQ(test, err, 0);
> >         kfree_at_end(test, got.start); /* just in case */
> >
>
> It'd be nice to add some more tests for attribute filtering specifically here.

Yeah, I agree. I will go ahead and add some here.

Thanks for all the comments!
-Rae

>
>
>
> > --
> > 2.41.0.162.gfafddb0af9-goog
> >

On Tue, Jun 13, 2023 at 4:26 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Sat, Jun 10, 2023 at 12:51:46AM +0000, Rae Moar wrote:
> > Add filtering of test attributes. Users can filter tests using a
> > module_param_array called "filter". This functionality will be added to
> > kunit.py in the next patch.
> >
> > The filters will be imputed in the format:
> > "<attribute_name><operation><attribute_value>"
> >
> > Example: "speed>slow"
> >
> > Operations include: >, <, >=, <=, !=, and =. These operations do not need
> > to act the same for every attribute.
>
> How is the "default" filter specified? Is explicitly unfiltered? (i.e.
> "slow" stuff will run by default?) Or should there be a default filter
> of "speed<slow" for the memcpy conversion?
>
> But yes, I'm a fan of this whole series! I would much prefer this to
> having one-off CONFIGs for slow tests. :)
>

Hello!

Great to hear that you are happy to see this series.

Currently if no filter is specified, tests will run unfiltered (so the
slow tests will run by default).

But I think the idea of having a "default" filter is really
interesting. I would definitely be open to adding a default filter
that only runs tests with speeds faster than slow, which could then be
overridden by any filter input.

This also means there could be suite specific default filters but that
may be a future implementation since we currently only have one
attribute.

Or alternatively we could have a file that includes a list of default
filters that could then be inputted and altered based on suite.

Thanks!
Rae

> --
> Kees Cook