[Test] Add tests for Tree

test/test_storage_map.py

@@ -12,7 +12,7 @@
 import torch
 
 from tensordict import assert_close, TensorDict
-from torchrl.data import LazyTensorStorage, ListStorage, MCTSForest
+from torchrl.data import LazyTensorStorage, ListStorage, MCTSForest, Tree
 from torchrl.data.map import (
     BinaryToDecimal,
     QueryModule,
@@ -248,6 +248,109 @@ def test_map_rollout(self):
         assert not contains[rollout.shape[-1] :].any()
 
 
+# Tests Tree independent of MCTSForest
+class TestTree:
+    def dummy_tree(self):
+        """Creates a tree with the following node IDs:
+
+        0
+        ├── 1
+        |   ├── 3
+        |   └── 4
+        └── 2
+            ├── 5
+            └── 6
+        """
+
+        class IDGen:
+            def __init__(self):
+                self.next_id = 0
+
+            def __call__(self):
+                res = self.next_id
+                self.next_id += 1
+                return res
+
+        gen_id = IDGen()
+        gen_hash = lambda: hash(torch.rand(1).item())
+
+        def dummy_node_stack(obervations):
+            return TensorDict.lazy_stack(
+                [
+                    Tree(
+                        node_data=TensorDict({"obs": torch.tensor(obs)}),
+                        hash=gen_hash(),
+                        node_id=gen_id(),
+                    )
+                    for obs in obervations
+                ]
+            )
+
+        tree = dummy_node_stack([0])[0]
+        tree.subtree = dummy_node_stack([1, 2])
+        tree.subtree[0].subtree = dummy_node_stack([3, 4])
+        tree.subtree[1].subtree = dummy_node_stack([6, 7])
+        return tree
+
+    # Checks that when adding nodes to a tree, the `parent` property is set
+    # correctly
+    def test_parents(self):
+        tree = self.dummy_tree()
+
+        def check_parents_recursive(tree, parent):
+            if parent is None:
+                if tree.parent is not None:
+                    return False
+            elif tree.parent.node_data is not parent.node_data:
+                return False
+
+            if tree.subtree is not None:
+                for subtree in tree.subtree:
+                    if not check_parents_recursive(subtree, tree):
+                        return False
+
+            return True
+
+        assert check_parents_recursive(tree, None)
+
+    def test_vertices(self):
+        tree = self.dummy_tree()
+        N = 7
+        assert tree.num_vertices(count_repeat=False) == N
+        assert tree.num_vertices(count_repeat=True) == N
+        assert len(tree.vertices(key_type="hash")) == N
+        assert len(tree.vertices(key_type="id")) == N
+        assert len(tree.vertices(key_type="path")) == N
+
+        for path, vertex in tree.vertices(key_type="path").items():
+            vertex_check = tree
+            for i in path:
+                vertex_check = vertex_check.subtree[i]
+            assert vertex.node_data is vertex_check.node_data
+
+    def test_in(self):
+        for tree in self.dummy_tree().vertices().values():
+            for path, subtree in tree.vertices(key_type="path").items():
+                assert subtree in tree
+
+                if len(path) == 0:
+                    assert tree in subtree
+                else:
+                    assert tree not in subtree
+
+    def test_valid_paths(self):
+        tree = self.dummy_tree()
+        paths = set(tree.valid_paths())
+        paths_check = {(0, 0), (0, 1), (1, 0), (1, 1)}
+        assert paths == paths_check
+
+    def test_edges(self):
+        tree = self.dummy_tree()
+        edges = set(tree.edges())
+        edges_check = {(0, 1), (0, 2), (1, 3), (1, 4), (2, 5), (2, 6)}
+        assert edges == edges_check
+
+
 class TestMCTSForest:
     def dummy_rollouts(self) -> Tuple[TensorDict, ...]:
         """