Add some simple unit tests for sanity.

conftest.py

@@ -0,0 +1,51 @@
+from collections import defaultdict
+import pytest
+from speller import Graph, Node
+
+
+@pytest.fixture()
+def test_graph():
+    """Return a `speller.Graph` object of the word 'because'."""
+    test_graph = Graph()
+
+    test_graph._parents_of = defaultdict(
+        set,
+        {
+            Node(value='c', position=2): {Node(value='be', position=0)},
+            Node(value='au', position=3): {Node(value='c', position=2)},
+            Node(value='s', position=5): {
+                Node(value='au', position=3),
+                Node(value='u', position=4)
+            },
+            Node(value='se', position=5): {
+                Node(value='au', position=3),
+                Node(value='u', position=4)
+            },
+            None: {Node(value='se', position=5)},
+            Node(value='ca', position=2): {Node(value='be', position=0)},
+            Node(value='u', position=4): {Node(value='ca', position=2)}
+        }
+    )
+
+    test_graph._children_of = defaultdict(
+        set,
+        {
+            None: {Node(value='be', position=0), Node(value='b', position=0)},
+            Node(value='be', position=0): {
+                Node(value='ca', position=2),
+                Node(value='c', position=2)
+            },
+            Node(value='c', position=2): {Node(value='au', position=3)},
+            Node(value='au', position=3): {
+                Node(value='se', position=5),
+                Node(value='s', position=5)
+            },
+            Node(value='ca', position=2): {Node(value='u', position=4)},
+            Node(value='u', position=4): {
+                Node(value='se', position=5),
+                Node(value='s', position=5)
+            }
+        }
+    )
+
+    return test_graph

tests.py

@@ -1,4 +1,6 @@
+from collections import defaultdict
 import speller
+from speller import Node
 
 ELEMENTS = {
     'H', 'He', 'Li', 'Be', 'B', 'C', 'N', 'O', 'F', 'Ne', 'Na', 'Mg', 'Al',
@@ -15,11 +17,149 @@
 
 
 def test_verify_data():
+    """Assert that the set of elements in `speller.py` matches this
+    canonical set.
+    """
     assert speller.ELEMENTS == ELEMENTS
 
 
 def test_elemental_spelling():
+    """Assert that we get the expected results when spelling various
+    inputs.
+    """
     assert speller.spell('amputation') == [
         ('Am', 'Pu', 'Ta', 'Ti', 'O', 'N'),
         ('Am', 'P', 'U', 'Ta', 'Ti', 'O', 'N')
     ]
+    assert speller.spell('') == []
+    assert speller.spell('o') == [('O',)]
+
+
+def test_find_all_paths():
+    """Make simple graph with some branches, and assert that we find all
+    the paths from the first node to the last.
+    """
+    parents_to_children = {
+        'a': {'b'},
+        'b': {'c'},
+        'c': {'d'},
+        'd': {'e', 'y', 'z'},
+        'e': {'f', 'x'},
+        'f': {'g', 'x'},
+        'g': {'h'},
+        'h': {'i'},
+        'x': {'y'},
+        'y': {'z'},
+    }
+
+    assert set(speller.find_all_paths(parents_to_children, 'a', 'z')) == set([
+        ('a', 'b', 'c', 'd', 'z'),
+        ('a', 'b', 'c', 'd', 'y', 'z'),
+        ('a', 'b', 'c', 'd', 'e', 'x', 'y', 'z'),
+        ('a', 'b', 'c', 'd', 'e', 'f', 'x', 'y', 'z'),
+    ])
+
+
+def test_build_spelling_graph():
+    """Make a `speller.Graph` object, then build it with a word and
+    assert that it contains the proper node relationships.
+    """
+    g = speller.Graph()
+    speller.build_spelling_graph('because', g)
+
+    assert g._parents_of == defaultdict(
+        set,
+        {
+            Node(value='c', position=2): {Node(value='be', position=0)},
+            Node(value='au', position=3): {Node(value='c', position=2)},
+            Node(value='s', position=5): {
+                Node(value='au', position=3),
+                Node(value='u', position=4)
+            },
+            Node(value='se', position=5): {
+                Node(value='au', position=3),
+                Node(value='u', position=4)
+            },
+            None: {Node(value='se', position=5)},
+            Node(value='ca', position=2): {Node(value='be', position=0)},
+            Node(value='u', position=4): {Node(value='ca', position=2)}
+        }
+    )
+
+    assert g._children_of == defaultdict(
+        set,
+        {
+            None: {Node(value='be', position=0), Node(value='b', position=0)},
+            Node(value='be', position=0): {
+                Node(value='ca', position=2),
+                Node(value='c', position=2)
+            },
+            Node(value='c', position=2): {Node(value='au', position=3)},
+            Node(value='au', position=3): {
+                Node(value='se', position=5),
+                Node(value='s', position=5)
+            },
+            Node(value='ca', position=2): {Node(value='u', position=4)},
+            Node(value='u', position=4): {
+                Node(value='se', position=5),
+                Node(value='s', position=5)
+            }
+        }
+    )
+
+
+class TestGraph:
+    """Tests for the methods of the `speller.Graph` class."""
+
+    def test_firsts(self, test_graph):
+        """Assert that the graph properly identifies its first nodes."""
+        assert test_graph.firsts() == {Node('be', 0), Node('b', 0)}
+
+    def test_lasts(self, test_graph):
+        """Assert that the graph properly identifies its last nodes."""
+        assert test_graph.lasts() == {Node('se', 5)}
+
+    def test_add_edge(self, test_graph):
+        """Add an edge to the graph."""
+        parent = Node('te', 0)
+        child = Node('st', 2)
+        test_graph.add_edge(parent, child)
+        assert test_graph._children_of[parent] == {child}
+        assert test_graph._parents_of[child] == {parent}
+
+    def test_add_edge_with_no_parent(self, test_graph):
+        """Add an edge with no parent to the graph. Assert that 'None'
+        isn't added to `_parents_of[child]`.
+        """
+        parent = None
+        child = Node('a', 0)
+        test_graph.add_edge(parent, child)
+        assert child in test_graph._children_of[parent]
+        assert None not in test_graph._parents_of[child]
+
+    def test_add_edge_with_no_child(self, test_graph):
+        """Add an edge with no child to the graph. Assert that `None`
+        isn't added to `_children_of[parent]`.
+        """
+        parent = Node('z', 25)
+        child = None
+        test_graph.add_edge(parent, child)
+        assert None not in test_graph._children_of[parent]
+        assert parent in test_graph._parents_of[child]
+
+    def test_edges(self, test_graph):
+        """Assert that the graph properly lists its edges."""
+        assert set(test_graph.edges()) == set([
+            (None, Node(value='b', position=0)),
+            (None, Node(value='be', position=0)),
+            (Node(value='be', position=0), Node(value='c', position=2)),
+            (Node(value='be', position=0), Node(value='ca', position=2)),
+            (Node(value='c', position=2), Node(value='au', position=3)),
+            (Node(value='au', position=3), Node(value='s', position=5)),
+            (Node(value='au', position=3), Node(value='se', position=5)),
+            (Node(value='ca', position=2), Node(value='u', position=4)),
+            (Node(value='u', position=4), Node(value='s', position=5)),
+            (Node(value='u', position=4), Node(value='se', position=5))
+        ])
+
+    #TODO(amin): add a test for test_graph.export().