Test Point Sample

Introduction

This examples demonstrate a simple technique to monitor and test activity occurring in another thread. The samples show a common testing scenario of this type: where we want to verify the behavior of a state machine.

if you are not familiar with test points you may find it helpful to review the Test Point article before proceeding.

Source under test

s2_testpoint_source.c / h

These files implement a simple state machine that we wish to test. The state machine runs in its own thread, and starts when the thread function StateControllerTask is executed.

The expected state transitions are as follows:

eSTART -> eIDLE -> eACTIVE -> eIDLE -> eEND

The states don't do any work; instead they just sleep() so there's some time spent in each one.

Each state transition is managed through a call to SetNewState() which communicates the state transition to the test thread using the srTEST_POINT() macro. We set the macro argument to the name of the state we are transitioning to as this is the 'value' of the testpoint that will be received by the test thread.

Tests Description

s2_testpoint_basic

This example implements three tests of the state machine implemented in s2_testpoint_source. These tests demonstrate the use of the srTEST_POINT_WAIT() macros to verify activity in another thread and srTEST_POINT_CHECK() macro to verify an already completed activity.

Each test follows the same pattern in preparing and using the test point feature:

1. specify the set of test points of interest - create an array of type srTestPointExpect_t which specifies the expected test points and optionally an array of type srTestPointUnexpect_t for unexpected
2. set the expectation array using srTestPointExpect()
3. start the state machine
4. use srTEST_POINT_CHECK() or srTEST_POINT_WAIT() macro to validate the expected test points

We create an "expectation" of activity and then validate the observed activity against the expectation using rules that we specify. If the expectation is met, the test passes; if the expectation is not met, the test fails.

The main difference between the tests is the values of the parameters provided to each test's validation API.

TestPoint_SyncExact

Here we verify an exact match between the contents of the expected array and the observed testpoints. The combination of srTEST_POINT_EXPECT_ORDERED and an unexpected list specifies that the test will pass only if:

• only the testpoints in the expected array are seen, and
• the testpoints are seen in the order specified

TestPoint_SyncLooseTimed

Here we loosen the restrictions of the exact test. By specifiying srTEST_POINT_EXPECT_UNORDERED and empty unexpected list, we now will:

• ignore any testpoints seen that aren't in the expected array. and
• disregard the order in which the testpoints are received

Note that the "IDLE" testpoint is now included in the expected array only once, but with an expected count of 2.

The srTEST_POINT_CHECK() will now cause the test to fail only if all of the expected testpoints are not seen (the specified number of times) within the timeout period.

TestPoint_AsynLooseTimed

This test is identical to the SyncLooseTimed test, except that we call srTEST_POINT_WAIT() and pass a timeout value to 400 milliseconds, which will result in a test failure, as it takes approximately 600 milliseconds for the testpoint expectations to be satisfied.