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# Copyright 2022 Alethea Katherine Flowers
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations
import pytest
from nox._resolver import CycleError, lazy_stable_topo_sort
@pytest.mark.parametrize(
("dependencies", "expected"),
[
# Assert typical example with the following features:
# 1. Topological sort.
# 2. Ignores nodes outside the subgraph of ``dependencies[root]`` and its
# (recursive) dependencies. (``"f"`` and ``"g"``).
# 3. Lazy (``"e"`` does not occur any earlier than it needs to for ``"d"``).
# 4. Obeys ``dependencies[node]`` order preference when possible (``"a"`` and
# ``"d"``, ``"c"`` and ``"b"``).
(
{
"a": ("c", "b"),
"b": (),
"c": (),
"d": ("e",),
"e": ("c",),
"f": ("b", "g"),
"g": (),
"0": ("a", "d"),
},
("c", "b", "a", "e", "d"),
),
# 1. Topological sort.
# 2. Ignores (``"f"`` and ``"g"``).
# 3. Lazy (``"b"``).
# 4. Obeys order preference (``"d"`` and ``"a"``).
# 4. Obeys order preference (``"c"`` and ``"b"``).
(
{
"a": ("c", "b"),
"b": (),
"c": (),
"d": ("e",),
"e": ("c",),
"f": ("b", "g"),
"g": (),
"0": ("d", "a"),
},
("c", "e", "d", "b", "a"),
),
# 1. Topological sort.
# 2. Ignores (``"f"`` and ``"g"``).
# 4. Ignores order preference (``"a"`` and ``"d"``) when it is impossible to
# both satisfy a pair preference and produce a producing a topological and
# lazy sort.
(
{
"a": ("d",),
"b": (),
"c": (),
"d": ("e",),
"e": ("c",),
"f": ("b", "g"),
"g": (),
"0": ("a", "d"),
},
("c", "e", "d", "a"),
),
# 1. Topological sort.
# 2. Ignores (``"f"`` and ``"g"``).
# 3. Lazy (``"e"``).
# 4. Obeys order preference (``"a"`` and ``"d"``).
# 4. Ignores order preference (``"c"`` and ``"b"``).
(
{
"a": ("c", "b"),
"b": (),
"c": ("b",),
"d": ("e",),
"e": ("c",),
"f": ("b",),
"0": ("a", "d"),
},
("b", "c", "a", "e", "d"),
),
# 1. Topological sort.
# 2. Ignores (``"f"``).
# 3. Lazy (``"c"``, ``"h"``, ``"a"``, and ``"e"``).
# 4. Obeys order preference (``"g"``, ``"a"``, and ``"d"``).
# 4. Obeys order preference (``"b"`` and ``"g"``).
# 4. Obeys order preference (``"b"`` and ``"h"``).
# 4. Ignores order preference (``"c"`` and ``"b"``). Note that this is despite
# the fact that the topological order between ``"b"`` and ``"c"`` is
# undefined. In the tests above, we only saw a pair order preference ignored
# because the topological order between that pair was defined. Here,
# however, the ``dependencies["a"]`` order preference between ``"b"`` and
# ``"c"`` is ignored because obeying this order preference cannot be done
# without making the sort non-lazy (here, calling ``"c"`` earlier than is
# required by one of its dependents (``"h"``) would be non-lazy).
(
{
"a": ("c", "b"),
"b": (),
"c": (),
"d": ("e",),
"e": ("c",),
"f": ("b", "g"),
"g": ("b", "h"),
"h": ("c",),
"0": ("g", "a", "d"),
},
("b", "c", "h", "g", "a", "e", "d"),
),
],
)
def test_lazy_stable_topo_sort(
dependencies: dict[str, tuple[str, ...]], expected: tuple[str, ...]
) -> None:
actual = tuple(lazy_stable_topo_sort(dependencies, "0"))
actual_with_root = tuple(lazy_stable_topo_sort(dependencies, "0", drop_root=False))
assert actual == actual_with_root[:-1] == expected
@pytest.mark.parametrize(
("dependencies", "expected_cycle"),
[
# Note that these cycles are inherent to the dependency graph; they cannot be
# resolved by ignoring the order preference for a pair in ``dependencies[node]``
# for some ``node``.
(
{
"a": ("b",),
"b": ("a",),
"0": ("a",),
},
("a", "b", "a"),
),
(
{
"a": ("c", "b"),
"b": (),
"c": ("a", "b"),
"0": ("a",),
},
("a", "c", "a"),
),
],
)
def test_lazy_stable_topo_sort_CycleError(
dependencies: dict[str, tuple[str, ...]], expected_cycle: tuple[str, ...]
) -> None:
with pytest.raises(CycleError) as exc_info:
tuple(lazy_stable_topo_sort(dependencies, "0"))
# While the exact cycle reported is not unique and is an implementation detail, this
# still serves as a regression test for unexpected changes in the implementation's
# behavior.
assert exc_info.value.args[1] == expected_cycle
|
