Reset Precondition state between activations

include/behaviortree_cpp/decorators/script_precondition.h

@@ -60,6 +60,12 @@ class PreconditionNode : public DecoratorNode
   }
 
 private:
+  void halt() override
+  {
+    _children_running = false;
+    DecoratorNode::halt();
+  }
+
   virtual BT::NodeStatus tick() override
   {
     loadExecutor();
@@ -72,19 +78,18 @@ class PreconditionNode : public DecoratorNode
 
     // Only check the 'if' script if we haven't started ticking the children yet.
     Ast::Environment env = { config().blackboard, config().enums };
-    bool tick_children =
-        _children_running || (_children_running = _executor(env).cast<bool>());
+    bool tick_children = _children_running || _executor(env).cast<bool>();
 
     if(!tick_children)
     {
       return else_return;
     }
 
     auto const child_status = child_node_->executeTick();
+    _children_running = (child_status == NodeStatus::RUNNING);
     if(isStatusCompleted(child_status))
     {
       resetChild();
-      _children_running = false;
     }
     return child_status;
   }

tests/gtest_preconditions.cpp

@@ -168,6 +168,53 @@ TEST(PreconditionsDecorator, ChecksConditionOnce)
   EXPECT_EQ(tree.tickOnce(), NodeStatus::SUCCESS);
 }
 
+TEST(PreconditionsDecorator, ChecksConditionAfterHalt)
+{
+  BehaviorTreeFactory factory;
+  factory.registerNodeType<KeepRunning>("KeepRunning");
+
+  const std::string xml_text = R"(
+    <root BTCPP_format="4">
+      <BehaviorTree ID="MainTree">
+        <Precondition if="A==0" else="FAILURE">
+          <KeepRunning/>
+        </Precondition>
+      </BehaviorTree>
+    </root>)";
+
+  auto tree = factory.createTreeFromText(xml_text);
+  tree.rootBlackboard()->set("A", 0);
+  EXPECT_EQ(tree.tickOnce(), NodeStatus::RUNNING);
+
+  tree.haltTree();
+  tree.rootBlackboard()->set("A", 1);
+  EXPECT_EQ(tree.tickOnce(), NodeStatus::FAILURE);
+}
+
+TEST(PreconditionsDecorator, ChecksConditionAfterSkippedChild)
+{
+  BehaviorTreeFactory factory;
+  factory.registerNodeType<KeepRunning>("KeepRunning");
+
+  const std::string xml_text = R"(
+    <root BTCPP_format="4">
+      <BehaviorTree ID="MainTree">
+        <Precondition if="A==0" else="FAILURE">
+          <KeepRunning _skipIf="skip"/>
+        </Precondition>
+      </BehaviorTree>
+    </root>)";
+
+  auto tree = factory.createTreeFromText(xml_text);
+  tree.rootBlackboard()->set("A", 0);
+  tree.rootBlackboard()->set("skip", true);
+  EXPECT_EQ(tree.tickOnce(), NodeStatus::SKIPPED);
+
+  tree.rootBlackboard()->set("A", 1);
+  tree.rootBlackboard()->set("skip", false);
+  EXPECT_EQ(tree.tickOnce(), NodeStatus::FAILURE);
+}
+
 TEST(PreconditionsDecorator, CanRunChildrenMultipleTimes)
 {
   BehaviorTreeFactory factory;