Remove dictionary from signature of tree_graph and tree_data (#4786)

* Deprecate attrs dict in json_graph.tree fns.

Replace attrs dict in signature with explicit kwargs and
add deprecation warning.

Adds tests that the behavior isn't changed and that warnings are
raised when expected.

* Add deprecations to list and ignore warnings in conftest.

* Modify cytoscape functions attrs deprecation.

* Cleanup cytoscape test suite.

1 files changed, 51 insertions, 35 deletions

diff --git a/networkx/readwrite/json_graph/tests/test_tree.py b/networkx/readwrite/json_graph/tests/test_tree.py
index d6aaf958..1912870f 100644
--- a/networkx/readwrite/json_graph/tests/test_tree.py
+++ b/networkx/readwrite/json_graph/tests/test_tree.py
@@ -4,38 +4,54 @@ import networkx as nx
 from networkx.readwrite.json_graph import tree_data, tree_graph
 
 
-class TestTree:
-    def test_graph(self):
-        G = nx.DiGraph()
-        G.add_nodes_from([1, 2, 3], color="red")
-        G.add_edge(1, 2, foo=7)
-        G.add_edge(1, 3, foo=10)
-        G.add_edge(3, 4, foo=10)
-        H = tree_graph(tree_data(G, 1))
-        nx.is_isomorphic(G, H)
-
-    def test_graph_attributes(self):
-        G = nx.DiGraph()
-        G.add_nodes_from([1, 2, 3], color="red")
-        G.add_edge(1, 2, foo=7)
-        G.add_edge(1, 3, foo=10)
-        G.add_edge(3, 4, foo=10)
-        H = tree_graph(tree_data(G, 1))
-        assert H.nodes[1]["color"] == "red"
-
-        d = json.dumps(tree_data(G, 1))
-        H = tree_graph(json.loads(d))
-        assert H.nodes[1]["color"] == "red"
-
-    def test_exception(self):
-        with pytest.raises(TypeError, match="is not a tree."):
-            G = nx.complete_graph(3)
-            tree_data(G, 0)
-        with pytest.raises(TypeError, match="is not directed."):
-            G = nx.path_graph(3)
-            tree_data(G, 0)
-        with pytest.raises(nx.NetworkXError, match="names are not unique."):
-            G = nx.MultiDiGraph()
-            G.add_node(0)
-            attrs = dict(id="node", children="node")
-            tree_data(G, 0, attrs)
+def test_graph():
+    G = nx.DiGraph()
+    G.add_nodes_from([1, 2, 3], color="red")
+    G.add_edge(1, 2, foo=7)
+    G.add_edge(1, 3, foo=10)
+    G.add_edge(3, 4, foo=10)
+    H = tree_graph(tree_data(G, 1))
+    nx.is_isomorphic(G, H)
+
+
+def test_graph_attributes():
+    G = nx.DiGraph()
+    G.add_nodes_from([1, 2, 3], color="red")
+    G.add_edge(1, 2, foo=7)
+    G.add_edge(1, 3, foo=10)
+    G.add_edge(3, 4, foo=10)
+    H = tree_graph(tree_data(G, 1))
+    assert H.nodes[1]["color"] == "red"
+
+    d = json.dumps(tree_data(G, 1))
+    H = tree_graph(json.loads(d))
+    assert H.nodes[1]["color"] == "red"
+
+
+def test_exceptions():
+    with pytest.raises(TypeError, match="is not a tree."):
+        G = nx.complete_graph(3)
+        tree_data(G, 0)
+    with pytest.raises(TypeError, match="is not directed."):
+        G = nx.path_graph(3)
+        tree_data(G, 0)
+    with pytest.raises(nx.NetworkXError, match="must be different."):
+        G = nx.MultiDiGraph()
+        G.add_node(0)
+        tree_data(G, 0, ident="node", children="node")
+
+
+# NOTE: To be removed when deprecation expires in 3.0
+def test_attrs_deprecation():
+    G = nx.path_graph(3, create_using=nx.DiGraph)
+    # No warnings when `attrs` kwarg not used
+    with pytest.warns(None) as record:
+        data = tree_data(G, 0)
+        H = tree_graph(data)
+    assert len(record) == 0
+    # DeprecationWarning issued when `attrs` is used
+    attrs = {"id": "foo", "children": "bar"}
+    with pytest.warns(DeprecationWarning):
+        data = tree_data(G, 0, attrs=attrs)
+    with pytest.warns(DeprecationWarning):
+        H = tree_graph(data, attrs=attrs)