Implementation of support for parameterized testing in KUnit.
This approach requires the creation of a test case using the
KUNIT_CASE_PARAM macro that accepts a generator function as input.
This generator function should return the next parameter given the
previous parameter in parameterized tests. It also provides
a macro to generate common-case generators.

Signed-off-by: Arpitha Raghunandan <98.a...@gmail.com>
Co-developed-by: Marco Elver <el...@google.com>
Signed-off-by: Marco Elver <el...@google.com>
---
Changes v2->v3:
- Modifictaion of generator macro and method
Changes v1->v2:
- Use of a generator method to access test case parameters

 include/kunit/test.h | 32 ++++++++++++++++++++++++++++++++
 lib/kunit/test.c     | 20 +++++++++++++++++++-
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index a423fffefea0..16bf9f334e2c 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -142,6 +142,12 @@ struct kunit_case {
        void (*run_case)(struct kunit *test);
        const char *name;
 
+       /*
+        * Pointer to test parameter generator function.
+        * Used only for parameterized tests.
+        */
+       void* (*generate_params)(void *prev);
+
        /* private: internal use only. */
        bool success;
        char *log;
@@ -162,6 +168,9 @@ 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 +217,15 @@ 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 +1760,18 @@ do {                                                     
                       \
                                                fmt,                           \
                                                ##__VA_ARGS__)
 
+/**
+ * KUNIT_PARAM_GENERATOR() - Helper method for test parameter generators
+ *                          required in parameterized tests.
+ * @name:  prefix of the name for the test parameter generator function.
+ * @prev: a pointer to the previous test parameter, NULL for first parameter.
+ * @array: a user-supplied pointer to an array of test parameters.
+ */
+#define KUNIT_PARAM_GENERATOR(name, array)                                     
                \
+       static void *name##_gen_params(void *prev)                              
                \
+       {                                                                       
                \
+               typeof((array)[0]) * __next = prev ? ((typeof(__next)) prev) + 
1 : (array);     \
+               return __next - (array) < ARRAY_SIZE((array)) ? __next : NULL;  
                \
+       }
+
 #endif /* _KUNIT_TEST_H */
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 750704abe89a..b70ab9b12f3b 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(NULL);
+               test->current_param = 0;
+
+               while (test->param_values) {
+                       test_case->run_case(test);
+                       test->param_values = 
test_case->generate_params(test->param_values);
+                       test->current_param++;
+               }
+       }
 }
 
 static void kunit_case_internal_cleanup(struct kunit *test)
-- 
2.25.1

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