def test_has_node():
t = Trie()
assert t.has_node(b"")
assert not t.has_node(b"a")
t[b"Hello"] = 0
assert t.has_node(b"He")
with pytest.raises(KeyError):
t[b"He"]
assert t.has_node(b"Hello")
assert not t.has_node(b"Hello!")
assert t[b"Hello"] == 0
def test_delitem():
t = Trie()
t[b"hellothere"] = 0
t[b"helloworld"] = 1
assert t[b"hellothere"] == 0
assert t[b"helloworld"] == 1
assert t.has_node(b"hello")
del t[b"hellothere"]
with pytest.raises(KeyError):
t[b"hellothere"]
assert not t.has_node(b"hellothere")
assert not t.has_node(b"hellot")
assert t.has_node(b"hello")
with pytest.raises(KeyError):
t[b"hello"]
assert t[b"helloworld"] == 1
# Test removing strings with insertions staggered
t = Trie()
strings = [b"AB", b"ABCD", b"ABCDEFG", b"ABCDEFGHIJK"]
for i, s in enumerate(strings):
t[s] = i;
assert t[b"AB"] == 0
assert t[b"ABCDEFGHIJK"] == 3
del t[b"AB"]
assert t.has_node(b"AB")
# Make sure string is removed
with pytest.raises(KeyError):
t[b"AB"]
# Check the other strings were not affected
for i, s in enumerate(strings[1:]):
assert t[s] == i + 1
# Should not be able to remove non-existent string
assert t.has_node(b"ABC")
with pytest.raises(Exception):
del t[b"ABC"]
with pytest.raises(Exception):
del t[b"ABCDEFGHIJKL"]
# Remove string in between two others
del t[b"ABCDEFG"]
assert t.has_node(b"ABCDEFG")
with pytest.raises(KeyError):
t[b"ABCDEFG"]
assert t[b"ABCDEFGHIJK"] == 3
# See if nodes are actually removed when a string at a leaf is removed
del t[b"ABCDEFGHIJK"]
assert t.has_node(b"ABCD")
assert t[b"ABCD"] == 1
assert not t.has_node(b"ABCDE")
with pytest.raises(KeyError):
t[b"ABCDEFG"]
with pytest.raises(KeyError):
t[b"ABCDEFGHIJK"]
# Remove the last string
del t[b"ABCD"]
assert not t.has_node(b"ABCD")
assert not t.has_node(b"A")
assert t.has_node(b"")
with pytest.raises(KeyError):
t[b""]
# Test edge case where empty string is inserted and removed
with pytest.raises(KeyError):
t[b""]
t[b""] = 0
assert t[b""] == 0
del t[b""]
assert t.has_node(b"")
with pytest.raises(KeyError):
t[b""]