TST: be more explicit about instance comparison. (#4748)

Some tests relied on __eq__ or __ne__ to check whether or
not two Graph instances where the same instance. Use is
and is not instead.

2 files changed, 14 insertions, 14 deletions

diff --git a/networkx/readwrite/tests/test_adjlist.py b/networkx/readwrite/tests/test_adjlist.py
index e2a655ef..0066111a 100644
--- a/networkx/readwrite/tests/test_adjlist.py
+++ b/networkx/readwrite/tests/test_adjlist.py
@@ -85,7 +85,7 @@ class TestAdjlist:
         nx.write_adjlist(G, fname)
         H = nx.read_adjlist(fname)
         H2 = nx.read_adjlist(fname)
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -97,7 +97,7 @@ class TestAdjlist:
         nx.write_adjlist(G, fname)
         H = nx.read_adjlist(fname, create_using=nx.DiGraph())
         H2 = nx.read_adjlist(fname, create_using=nx.DiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -109,7 +109,7 @@ class TestAdjlist:
         nx.write_adjlist(G, fname)
         H = nx.read_adjlist(fname, nodetype=int)
         H2 = nx.read_adjlist(fname, nodetype=int)
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -121,7 +121,7 @@ class TestAdjlist:
         nx.write_adjlist(G, fname)
         H = nx.read_adjlist(fname, nodetype=int, create_using=nx.MultiGraph())
         H2 = nx.read_adjlist(fname, nodetype=int, create_using=nx.MultiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -133,7 +133,7 @@ class TestAdjlist:
         nx.write_adjlist(G, fname)
         H = nx.read_adjlist(fname, nodetype=int, create_using=nx.MultiDiGraph())
         H2 = nx.read_adjlist(fname, nodetype=int, create_using=nx.MultiDiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -196,7 +196,7 @@ class TestMultilineAdjlist:
         nx.write_multiline_adjlist(G, fname)
         H = nx.read_multiline_adjlist(fname)
         H2 = nx.read_multiline_adjlist(fname)
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -208,7 +208,7 @@ class TestMultilineAdjlist:
         nx.write_multiline_adjlist(G, fname)
         H = nx.read_multiline_adjlist(fname, create_using=nx.DiGraph())
         H2 = nx.read_multiline_adjlist(fname, create_using=nx.DiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -220,7 +220,7 @@ class TestMultilineAdjlist:
         nx.write_multiline_adjlist(G, fname)
         H = nx.read_multiline_adjlist(fname, nodetype=int)
         H2 = nx.read_multiline_adjlist(fname, nodetype=int)
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -234,7 +234,7 @@ class TestMultilineAdjlist:
         H2 = nx.read_multiline_adjlist(
             fname, nodetype=int, create_using=nx.MultiGraph()
         )
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -250,7 +250,7 @@ class TestMultilineAdjlist:
         H2 = nx.read_multiline_adjlist(
             fname, nodetype=int, create_using=nx.MultiDiGraph()
         )
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
diff --git a/networkx/readwrite/tests/test_edgelist.py b/networkx/readwrite/tests/test_edgelist.py
index f159f2b1..de3f0146 100644
--- a/networkx/readwrite/tests/test_edgelist.py
+++ b/networkx/readwrite/tests/test_edgelist.py
@@ -250,7 +250,7 @@ class TestEdgelist:
         nx.write_edgelist(G, fname)
         H = nx.read_edgelist(fname)
         H2 = nx.read_edgelist(fname)
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         G.remove_node("g")  # isolated nodes are not written in edgelist
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
@@ -263,7 +263,7 @@ class TestEdgelist:
         nx.write_edgelist(G, fname)
         H = nx.read_edgelist(fname, create_using=nx.DiGraph())
         H2 = nx.read_edgelist(fname, create_using=nx.DiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         G.remove_node("g")  # isolated nodes are not written in edgelist
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
@@ -288,7 +288,7 @@ class TestEdgelist:
         nx.write_edgelist(G, fname)
         H = nx.read_edgelist(fname, nodetype=int, create_using=nx.MultiGraph())
         H2 = nx.read_edgelist(fname, nodetype=int, create_using=nx.MultiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)
@@ -300,7 +300,7 @@ class TestEdgelist:
         nx.write_edgelist(G, fname)
         H = nx.read_edgelist(fname, nodetype=int, create_using=nx.MultiDiGraph())
         H2 = nx.read_edgelist(fname, nodetype=int, create_using=nx.MultiDiGraph())
-        assert H != H2  # they should be different graphs
+        assert H is not H2  # they should be different graphs
         assert_nodes_equal(list(H), list(G))
         assert_edges_equal(list(H.edges()), list(G.edges()))
         os.close(fd)