Test Point Testing in C/C++

Introduction

Test Point Expectations tests can be written in native code (C/C++) and executed on the device under test using the STRIDE framework. In some cases, creating tests that run on the device itself might be preferable to host/script based tests, particularly if dealing with complex binary data payloads from test points.

Instrumenting Source Code

Before any useful tests can be written, the source under test must be strategically instrumented with STRIDE Test Point macros. See this article for information on how to accomplish that.

Creating Test Point Tests

Test code to validate the Expectations of the Test Points often follows this basic pattern:

1. Specify an expectation set consisting of expected (i.e. the test points that are expected to be hit) and optionally unexpected (i.e. the test points that are not expected to be hit) test points
2. Register the expectation set with the STRIDE runtime
3. Invoke the software under test (causing instrumentation points to be hit). This may not be necessary if the instrumented software under test is constantly running).
4. Wait for the expectation set to be satisfied or a timeout to occur

Here is an example:

#include <srtest.h>

void tf_testpoint_wait(void)
{
  /* specify expected set */
  srTestPointExpect_t expected[]= {
        {"START"}, 
        {"ACTIVE"}, 
        {"IDLE"},
        {"END"}, 
        {0}};

  /* specify unexpected set */
  srTestPointUnexpect_t unexpected[]= {
        {"INVALID"}, 
        {0}};

  /* register the expectation set with the STRIDE */
  srWORD handle;
  srTestPointSetup(expected, unexpected, srTEST_POINT_EXPECT_UNORDERED, srTEST_CASE_DEFAULT, &handle);

  /* start your asynchronous operation */
  ...

  /* wait for expectation set to be satisfied or a timeout to occur */
  srTestPointWait(handle, 1000);
}

#ifdef _SCL
#pragma scl_test_flist(“testfunc”, tf_testpoint_wait)
#endif

Reference

Expectation Set

An expectation set is specified with an expected array of srTestPointExpect_t structures and a second optional unexpected array of srTestPointUnexpect_t structures.

Expected Array

srTestPointExpect_t is typedef'd as follows:

typedef struct
{
    /* the label value is considered the test point's identity */
    const srCHAR *          label;
    /* optional, count specifies the number of times the test point is expected to be hit */ 
    srDWORD                 count;
    /* optional, predicate function to use for payload validation against user data */ 
    srTestPointPredicate_t  predicate;
    /* optional, user data to validate the payload against */
    void *                  user;
} srTestPointExpect_t;

NOTES:

• The end of the array has to be marked by a srTestPointExpect_t set to all zero values
• The count, predicate and user members may be omitted in the array declaration (they will be automatically set to 0 by the compiler)
• A count value of either 0 or 1 is interpreted as 1
• The count could be set as "0 or more" by using the special srTEST_POINT_ANY_COUNT symbolic constant
• A predicate value 0 indicates that any associated with a test point payload will be ignored.
• A user value 0 indicates that there is no user data associated with this test point
• The label could be specified to any test point within the current universe by using the special srTEST_POINT_ANYTHING symbolic constant.

Unexpected Array

srTestPointUnexpect_t is typedef'd as follows:

typedef struct
{
    /* the label value is considered the test point's identity */
    const srCHAR *          label;
} srTestPointUnexpect_t;

NOTES:

• The end of the array has to be marked by a srTestPointUnexpect_t set to all zero values
• The label could be specified to everything else relative to the expected array by using the special srTEST_POINT_EVERYTHING_ELSE symbolic constant.

srTestPointPredicate_t

When defining the expectation set per entry a payload validation predicate function could be specified. The signature of it should match the following type:

typedef srBYTE (*srTestPointPredicate_t)(const srTestPoint_t* ptTP, void* pvUser);

Parameters	Type	Description
ptTP	Input	Pointer to the currently processed Test Point.
pvUser	Input	Pointer to opaque user data associated with an entry in the expectation set.

Return Value	Description
srBYTE	srTRUE for valid, srFALSE for invalid, srIGNORE otherwise.

NOTE:

• As part of the standard STRIDE distribution there are three predefined function predicate helpers:
  • srTestPointMemCmp - byte comparison
  • srTestPointStrCmp - string case sensitive comparison
  • srTestPointStrCaseCmp - string case insensitive comparison

srTestPointSetup

The srTestPointSetup() routine is used to register an expectation set.

srBOOL srTestPointSetup(srTestPointExpect_t* ptExpected, 
                        srTestPointUnexpect_t* ptUnexpected, 
                        srBYTE yMode, 
                        srTestCaseHandle_t tTestCase, 
                        srWORD* pwHandle);

Parameters	Type	Description
ptExpected	Input	Pointer to an expectated array.
ptUnexpected	Input	Pointer to an unexpectated array. This is optional and could be set srNULL.
yMode	Input	Bitmask that specifies whether the expectated test points occur in order and/or strict. Possible values are: srTEST_POINT_EXPECT_ORDERED - the test points are expected to be hit exactly in the defined order srTEST_POINT_EXPECT_UNORDERED - the test points could to be hit in any order srTEST_POINT_EXPECT_STRICT - the test points are expected to be hit exactly as specified srTEST_POINT_EXPECT_NONSTRICT - other test points from the universe could to be hit in between
tTestCase	Input	Handle to a test case. srTEST_CASE_DEFAULT can be used for the default test case.
pwHandle	Output	Handle that represents the registered expectation set

Return Value	Description
srBOOL	srTRUE on success, srFALSE otherwise.

srTestPointWait

The srTestPointWait() routine is used to wait for the expectation to be satisfied.

srBOOL srTestPointWait(srWORD wHandle, 
                       srDWORD dwTimeout);

Parameters	Type	Description
wHandle	Input	Handle to a registered expectation set.
dwTimeout	Input	Timeout value in milliseconds; 0 means just check without waiting.

Return Value	Description
srBOOL	srTRUE on success, srFALSE otherwise.

NOTES:

• The test thread blocks until either the expectation set is satisfied or the timeout elapses.
• All test points hit during the wait (both expected and unexpected) are added to the test report as testcase comments
• Once the wait is over (whether the expectation set has been satisfied or there has been a test failure), the current expectation set is automatically unregistered from the STRIDE runtime and the handle is released
• If you want to return immediately from a test case if expectation fails then make the check/wait call an argument to srASSERT_TRUE().

srTestPointCheck

The srTestPointCheck() routine is used to check for the expectation post routine completion. This is useful for verifying a set of expectations events that should have already transpired (thus are waiting to be processed).

srBOOL srTestPointCheck(srWORD wHandle);

Parameters	Type	Description
wHandle	Input	Handle to a registered expectation set.

Return Value	Description
srBOOL	srTRUE on success, srFALSE otherwise.

NOTES:

• All test points hit before the check (both expected and unexpected) are added to the test report as testcase comments
• Once the check is done (whether the expectation set has been satisfied or there has been a test failure), the current expectation set is automatically unregistered from the STRIDE runtime and the handle is released
• If you want to return immediately from a test case if expectation fails then make the check/wait call an argument to srASSERT_TRUE().

C++ Facade Class

The srtest.h file provides a simple facade class that wraps the test point APIs described above in a simple C++ class called srTestPointsHandler. If you are writing your unit tests in C++ (using STRIDE test classes), then this class is available for your use. The class implements the following methods, which correspond exactly to the C API equivalents:

srTestPointsHandler

constructor. Takes four arguments which match exactly the first four parameters of the srTestPointSetup function.

Wait

instance method that provides same functionality as srTestPointWait.

Check

instance method that provides same functionality as srTestPointCheck.