Fix warnings from running tests in randomized order (#6014)

* Use toarray instead of .A for sparse array conversion.

Missed this example in the test suite during the sparse
cleanup.

* Fix crosstalk of axis object between tests.

This now raises a dep warning for mpl 3.6 and will result in
explicit exceptions in the future.

2 files changed, 5 insertions, 4 deletions

diff --git a/networkx/drawing/tests/test_pylab.py b/networkx/drawing/tests/test_pylab.py
index 33ce4e85..f642dcc4 100644
--- a/networkx/drawing/tests/test_pylab.py
+++ b/networkx/drawing/tests/test_pylab.py
@@ -485,18 +485,19 @@ def test_multigraph_edgelist_tuples():
 
 def test_alpha_iter():
     pos = nx.random_layout(barbell)
+    fig = plt.figure()
     # with fewer alpha elements than nodes
-    plt.subplot(131)
+    fig.add_subplot(131)  # Each test in a new axis object
     nx.draw_networkx_nodes(barbell, pos, alpha=[0.1, 0.2])
     # with equal alpha elements and nodes
     num_nodes = len(barbell.nodes)
     alpha = [x / num_nodes for x in range(num_nodes)]
     colors = range(num_nodes)
-    plt.subplot(132)
+    fig.add_subplot(132)
     nx.draw_networkx_nodes(barbell, pos, node_color=colors, alpha=alpha)
     # with more alpha elements than nodes
     alpha.append(1)
-    plt.subplot(133)
+    fig.add_subplot(133)
     nx.draw_networkx_nodes(barbell, pos, alpha=alpha)
 
 
diff --git a/networkx/generators/tests/test_expanders.py b/networkx/generators/tests/test_expanders.py
index 738773fd..822eeee0 100644
--- a/networkx/generators/tests/test_expanders.py
+++ b/networkx/generators/tests/test_expanders.py
@@ -30,7 +30,7 @@ def test_margulis_gabber_galil_graph():
 
     # Eigenvalues are already sorted using the scipy eigvalsh,
     # but the implementation in numpy does not guarantee order.
-    w = sorted(sp.linalg.eigvalsh(adjacency_matrix(g).A))
+    w = sorted(sp.linalg.eigvalsh(adjacency_matrix(g).toarray()))
     assert w[-2] < 5 * np.sqrt(2)