add realistic root knowledge mode to treetest

treetest/tests/knowledge.rs

@@ -0,0 +1,41 @@
+use treetest::{model::NodeId, scenarios::built_in_scenarios, sim::Simulation};
+
+#[test]
+fn realistic_mode_memory_reset_forgets_deeper_nodes() {
+    let scenarios = built_in_scenarios();
+    let mut simulation = Simulation::new(scenarios[2].clone()).expect("scenario should build");
+
+    simulation
+        .call_echo_leaf(NodeId(2), "echo", "learn this nested leaf")
+        .expect("echo call should start");
+    simulation.drain().expect("network should drain");
+
+    assert!(
+        simulation
+            .root_knowledge
+            .node(&simulation.node(NodeId(2)).path)
+            .is_some()
+    );
+
+    simulation.enable_realistic_mode_with_memory_reset();
+
+    assert!(simulation.is_realistic_mode());
+    assert!(
+        simulation
+            .root_knowledge
+            .node(&simulation.node(NodeId(2)).path)
+            .is_none()
+    );
+    assert!(
+        simulation
+            .root_knowledge
+            .node(&simulation.node(NodeId(1)).path)
+            .is_some()
+    );
+    assert!(
+        simulation
+            .root_knowledge
+            .node(&simulation.node(NodeId(0)).path)
+            .is_some()
+    );
+}