Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/networkx/readwrite/tests/test_sparse6.py

@@ -0,0 +1,173 @@
+from io import BytesIO
+import tempfile
+import pytest
+
+import networkx as nx
+from networkx.testing.utils import assert_edges_equal
+from networkx.testing.utils import assert_nodes_equal
+
+
+class TestSparseGraph6:
+    def test_from_sparse6_bytes(self):
+        data = b":Q___eDcdFcDeFcE`GaJ`IaHbKNbLM"
+        G = nx.from_sparse6_bytes(data)
+        assert_nodes_equal(
+            sorted(G.nodes()),
+            [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17],
+        )
+        assert_edges_equal(
+            G.edges(),
+            [
+                (0, 1),
+                (0, 2),
+                (0, 3),
+                (1, 12),
+                (1, 14),
+                (2, 13),
+                (2, 15),
+                (3, 16),
+                (3, 17),
+                (4, 7),
+                (4, 9),
+                (4, 11),
+                (5, 6),
+                (5, 8),
+                (5, 9),
+                (6, 10),
+                (6, 11),
+                (7, 8),
+                (7, 10),
+                (8, 12),
+                (9, 15),
+                (10, 14),
+                (11, 13),
+                (12, 16),
+                (13, 17),
+                (14, 17),
+                (15, 16),
+            ],
+        )
+
+    def test_from_bytes_multigraph_graph(self):
+        graph_data = b":An"
+        G = nx.from_sparse6_bytes(graph_data)
+        assert type(G) == nx.Graph
+        multigraph_data = b":Ab"
+        M = nx.from_sparse6_bytes(multigraph_data)
+        assert type(M) == nx.MultiGraph
+
+    def test_read_sparse6(self):
+        data = b":Q___eDcdFcDeFcE`GaJ`IaHbKNbLM"
+        G = nx.from_sparse6_bytes(data)
+        fh = BytesIO(data)
+        Gin = nx.read_sparse6(fh)
+        assert_nodes_equal(G.nodes(), Gin.nodes())
+        assert_edges_equal(G.edges(), Gin.edges())
+
+    def test_read_many_graph6(self):
+        # Read many graphs into list
+        data = b":Q___eDcdFcDeFcE`GaJ`IaHbKNbLM\n" b":Q___dCfDEdcEgcbEGbFIaJ`JaHN`IM"
+        fh = BytesIO(data)
+        glist = nx.read_sparse6(fh)
+        assert len(glist) == 2
+        for G in glist:
+            assert_nodes_equal(
+                G.nodes(),
+                [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17],
+            )
+
+
+class TestWriteSparse6:
+    """Unit tests for writing graphs in the sparse6 format.
+
+    Most of the test cases were checked against the sparse6 encoder in Sage.
+
+    """
+
+    def test_null_graph(self):
+        G = nx.null_graph()
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:?\n"
+
+    def test_trivial_graph(self):
+        G = nx.trivial_graph()
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:@\n"
+
+    def test_empty_graph(self):
+        G = nx.empty_graph(5)
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:D\n"
+
+    def test_large_empty_graph(self):
+        G = nx.empty_graph(68)
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:~?@C\n"
+
+    def test_very_large_empty_graph(self):
+        G = nx.empty_graph(258049)
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:~~???~?@\n"
+
+    def test_complete_graph(self):
+        G = nx.complete_graph(4)
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        assert result.getvalue() == b">>sparse6<<:CcKI\n"
+
+    def test_no_header(self):
+        G = nx.complete_graph(4)
+        result = BytesIO()
+        nx.write_sparse6(G, result, header=False)
+        assert result.getvalue() == b":CcKI\n"
+
+    def test_padding(self):
+        codes = (b":Cdv", b":DaYn", b":EaYnN", b":FaYnL", b":GaYnLz")
+        for n, code in enumerate(codes, start=4):
+            G = nx.path_graph(n)
+            result = BytesIO()
+            nx.write_sparse6(G, result, header=False)
+            assert result.getvalue() == code + b"\n"
+
+    def test_complete_bipartite(self):
+        G = nx.complete_bipartite_graph(6, 9)
+        result = BytesIO()
+        nx.write_sparse6(G, result)
+        # Compared with sage
+        expected = b">>sparse6<<:Nk" + b"?G`cJ" * 9 + b"\n"
+        assert result.getvalue() == expected
+
+    def test_read_write_inverse(self):
+        for i in list(range(13)) + [31, 47, 62, 63, 64, 72]:
+            m = min(2 * i, i * i // 2)
+            g = nx.random_graphs.gnm_random_graph(i, m, seed=i)
+            gstr = BytesIO()
+            nx.write_sparse6(g, gstr, header=False)
+            # Strip the trailing newline.
+            gstr = gstr.getvalue().rstrip()
+            g2 = nx.from_sparse6_bytes(gstr)
+            assert g2.order() == g.order()
+            assert_edges_equal(g2.edges(), g.edges())
+
+    def test_no_directed_graphs(self):
+        with pytest.raises(nx.NetworkXNotImplemented):
+            nx.write_sparse6(nx.DiGraph(), BytesIO())
+
+    def test_write_path(self):
+        # On Windows, we can't reopen a file that is open
+        # So, for test we get a valid name from tempfile but close it.
+        with tempfile.NamedTemporaryFile() as f:
+            fullfilename = f.name
+        # file should be closed now, so write_sparse6 can open it
+        nx.write_sparse6(nx.null_graph(), fullfilename)
+        fh = open(fullfilename, mode="rb")
+        assert fh.read() == b">>sparse6<<:?\n"
+        fh.close()
+        import os
+
+        os.remove(fullfilename)