Fix nasa#1769, add call to CFE_ES_ExitChildTask

Invoke CFE_ES_ExitChildTask from the main test task, to confirm
that the task does not actually exit.  There is no status code
but the fact that the test keeps running is evidence that the
task did not exit (which means the test passed).

modules/cfe_testcase/src/es_task_test.c

@@ -88,6 +88,16 @@ void TestCreateChild(void)
                       CFE_ES_BAD_ARGUMENT);
     UtAssert_INT32_EQ(CFE_ES_CreateChildTask(&TaskId, TaskName, TaskFunction, StackPointer, 0, Priority, Flags),
                       CFE_STATUS_EXTERNAL_RESOURCE_FAIL);
+
+    /*
+     * Invoking CFE_ES_ExitChildTask() from the context of a main task should _not_ actually exit.
+     * as this is a void function there is no return code to check here.  The fact that the test
+     * continues after this call is evidence that the test passed (i.e. it did not actually end the task).
+     */
+    UtAssert_VOIDCALL(CFE_ES_ExitChildTask());
+
+    /* If this message is printed, then the test passed.  If the test fails this will not be reached. */
+    UtAssert_True(true, "CFE_ES_ExitChildTask() called from main task (ignored; main task did not exit)");
 }
 
 void TestChildTaskName(void)