1 files changed, 53 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/tree/tests/test_operations.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/tree/tests/test_operations.py
new file mode 100644
index 00000000..284d94e2
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/tree/tests/test_operations.py
@@ -0,0 +1,53 @@
+from itertools import chain
+
+import networkx as nx
+from networkx.utils import edges_equal, nodes_equal
+
+
+def _check_custom_label_attribute(input_trees, res_tree, label_attribute):
+    res_attr_dict = nx.get_node_attributes(res_tree, label_attribute)
+    res_attr_set = set(res_attr_dict.values())
+    input_label = (tree for tree, root in input_trees)
+    input_label_set = set(chain.from_iterable(input_label))
+    return res_attr_set == input_label_set
+
+
+def test_empty_sequence():
+    """Joining the empty sequence results in the tree with one node."""
+    T = nx.join_trees([])
+    assert len(T) == 1
+    assert T.number_of_edges() == 0
+
+
+def test_single():
+    """Joining just one tree yields a tree with one more node."""
+    T = nx.empty_graph(1)
+    trees = [(T, 0)]
+    actual_with_label = nx.join_trees(trees, label_attribute="custom_label")
+    expected = nx.path_graph(2)
+    assert nodes_equal(list(expected), list(actual_with_label))
+    assert edges_equal(list(expected.edges()), list(actual_with_label.edges()))
+
+
+def test_basic():
+    """Joining multiple subtrees at a root node."""
+    trees = [(nx.full_rary_tree(2, 2**2 - 1), 0) for i in range(2)]
+    expected = nx.full_rary_tree(2, 2**3 - 1)
+    actual = nx.join_trees(trees, label_attribute="old_labels")
+    assert nx.is_isomorphic(actual, expected)
+    assert _check_custom_label_attribute(trees, actual, "old_labels")
+
+    actual_without_label = nx.join_trees(trees)
+    assert nx.is_isomorphic(actual_without_label, expected)
+    # check that no labels were stored
+    assert all(not data for _, data in actual_without_label.nodes(data=True))
+
+
+def test_first_label():
+    """Test the functionality of the first_label argument."""
+    T1 = nx.path_graph(3)
+    T2 = nx.path_graph(2)
+    actual = nx.join_trees([(T1, 0), (T2, 0)], first_label=10)
+    expected_nodes = set(range(10, 16))
+    assert set(actual.nodes()) == expected_nodes
+    assert set(actual.neighbors(10)) == {11, 14}