fix(timer): Delete node, after executor thread terminated (#2737)

This fixes a potential race leading to a segfault. The segfault would
happen, if the tear down of the test would occur before the timer thread
stopped the spinning of the executor.

Also simplifies the test code, as the cancel of the executor is now in
the TearDown().

Signed-off-by: Janosch Machowinski <J.Machowinski@cellumation.com>
Co-authored-by: Janosch Machowinski <J.Machowinski@cellumation.com>

rclcpp/test/rclcpp/executors/test_executors_timer_cancel_behavior.cpp

@@ -267,12 +267,15 @@ class TestTimerCancelBehavior : public ::testing::Test
 
   void TearDown()
   {
-    node.reset();
+    executor.cancel();
 
     // Clean up thread object
     if (standalone_thread.joinable()) {
       standalone_thread.join();
     }
+
+    node.reset();
+    sim_clock_node.reset();
   }
 
   std::shared_ptr<TimerNode> node;
@@ -310,7 +313,6 @@ TYPED_TEST(TestTimerCancelBehavior, testTimer1CancelledWithExecutorSpin) {
   this->sim_clock_node->sleep_for(50ms);
   this->node->CancelTimer1();
   this->sim_clock_node->sleep_for(150ms);
-  this->executor.cancel();
 
   int t1_runs = this->node->GetTimer1Cnt();
   int t2_runs = this->node->GetTimer2Cnt();
@@ -328,7 +330,6 @@ TYPED_TEST(TestTimerCancelBehavior, testTimer2CancelledWithExecutorSpin) {
   this->sim_clock_node->sleep_for(50ms);
   this->node->CancelTimer2();
   this->sim_clock_node->sleep_for(150ms);
-  this->executor.cancel();
 
   int t1_runs = this->node->GetTimer1Cnt();
   int t2_runs = this->node->GetTimer2Cnt();
@@ -355,8 +356,6 @@ TYPED_TEST(TestTimerCancelBehavior, testHeadTimerCancelThenResetBehavior) {
   int t1_runs_final = this->node->GetTimer1Cnt();
   int t2_runs_final = this->node->GetTimer2Cnt();
 
-  this->executor.cancel();
-
   // T1 should have been restarted, and execute about 15 additional times.
   // Check 10 greater than initial, to account for some timing jitter.
   EXPECT_LT(t1_runs_initial + 50, t1_runs_final);
@@ -384,8 +383,6 @@ TYPED_TEST(TestTimerCancelBehavior, testBackTimerCancelThenResetBehavior) {
   int t1_runs_final = this->node->GetTimer1Cnt();
   int t2_runs_final = this->node->GetTimer2Cnt();
 
-  this->executor.cancel();
-
   // T2 should have been restarted, and execute about 15 additional times.
   // Check 10 greater than initial, to account for some timing jitter.
   EXPECT_LT(t2_runs_initial + 50, t2_runs_final);
@@ -419,8 +416,6 @@ TYPED_TEST(TestTimerCancelBehavior, testBothTimerCancelThenResetT1Behavior) {
   int t1_runs_final = this->node->GetTimer1Cnt();
   int t2_runs_final = this->node->GetTimer2Cnt();
 
-  this->executor.cancel();
-
   // T1 and T2 should have the same initial count.
   EXPECT_LE(std::abs(t1_runs_initial - t2_runs_initial), 1);
 
@@ -458,8 +453,6 @@ TYPED_TEST(TestTimerCancelBehavior, testBothTimerCancelThenResetT2Behavior) {
   int t1_runs_final = this->node->GetTimer1Cnt();
   int t2_runs_final = this->node->GetTimer2Cnt();
 
-  this->executor.cancel();
-
   // T1 and T2 should have the same initial count.
   EXPECT_LE(std::abs(t1_runs_initial - t2_runs_initial), 1);