Update test_utilities.py

Test
- flatten
- convert_to_adj
- add_edge_to
#7

test/test_utilities.py

@@ -19,4 +19,71 @@
     If not, see https://www.gnu.org/licenses/gpl-3.0.html
 
 """
+from pytest import param, mark, raises
+from tdvisu.utilities import flatten, convert_to_adj, add_edge_to
 
+
+@mark.parametrize(
+    "arg",
+    [None, 10, 1.4, [1, 2, 3], [None]]
+)
+def test_cant_flatten(arg):
+    """Fail the flatten method with TypeError"""
+    with raises(TypeError):
+        list(flatten(arg))
+
+
+@mark.parametrize(
+    "arg, expected",
+    [((), []),
+     ([], []),
+     (([None],), [None]),
+     ([(1, 2), (3, 4)], [1, 2, 3, 4]),
+     ([(1, 2)], [1, 2]),
+     ([""], []),
+     (["String"], ['S', 't', 'r', 'i', 'n', 'g']),
+     (["String", "Zwei", "Drei"], ['S', 't', 'r', 'i', 'n', 'g', 'Z', 'w', 'e', 'i', 'D', 'r', 'e', 'i'])
+     ]
+)
+def test_flatten(arg, expected):
+    """Test the flatten method."""
+    assert list(flatten(arg)) == expected
+
+
+def test_convert_to_adj():
+    """Test the convert_to_adj method"""
+    assert convert_to_adj([(2, 1), (3, 2), (4, 2), (5, 4)]) == {
+        2: {1: {}, 3: {}, 4: {}}, 1: {2: {}}, 3: {2: {}}, 4: {2: {}, 5: {}}, 5: {4: {}}}
+
+
+@mark.parametrize(
+    "edges, adj, vertex1, vertex2, new_adj",
+    [param(set(), {}, 1, 2, {1: {2}, 2: {1}},
+           id="empty sets 1"),
+     param(set(), {}, "B", "A", {"B": {"A"}, "A": {"B"}},
+           id="empty sets 2"),
+     param(set([1, 2, 3]), {}, 1, 2, {1: {2}, 2: {1}},
+           id="doesnt care about prev elements 1"),
+     param(set([None]), {}, "B", "A", {"B": {"A"}, "A": {"B"}},
+           id="doesnt care about prev elements 2"),
+     param({(1, 2), (2, 3)}, {1: {2}, 2: {1, 3}, 3: {2}}, 3, 1,
+
+           {1: {2, 3}, 2: {1, 3}, 3: {1, 2}},
+           id="Closing the triangle"),
+     param({('a', 1), (1, 2), (4.3, 2)}, {1: {2, 'a'}, 2: {1, 4.3}, 4.3: {2}, 'a': {1}},
+           2, "a",
+
+           {1: {2, 'a'}, 2: {1, 4.3, 'a'}, 4.3: {2}, 'a': {1, 2}},
+           id="Even with different elements everything works"),
+     ]
+)
+def test_add_edge_to(edges, adj, vertex1, vertex2, new_adj):
+    """Test the add_edge_to method. Sensitive to order in vertices in edges!"""
+    expect_edges = set(edges)
+    expect_edges.add((vertex1, vertex2))
+    add_edge_to(edges, adj, vertex1, vertex2)
+    assert edges == expect_edges
+    assert adj == new_adj
+    # adding second time switched does not change the adjacency
+    add_edge_to(edges, adj, vertex2, vertex1)
+    assert adj == new_adj