test_walk_dag.py
python
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fix: remove commit_exists filter from have anchors — server…
Sonnet 4.6
patch
22 days ago
| 1 | """TDD — walk_dag generic DAG walker (Phase 1). |
| 2 | |
| 3 | Tests are written against the planned public API before implementation. |
| 4 | All tests in this file are expected to FAIL until walk_dag is implemented |
| 5 | in muse/core/graph.py. |
| 6 | |
| 7 | Coverage |
| 8 | -------- |
| 9 | walk_dag |
| 10 | - empty starts → yields nothing |
| 11 | - single node, no neighbours → yields just that node |
| 12 | - linear chain BFS order (root last) |
| 13 | - linear chain DFS order (root last — same for a chain) |
| 14 | - diamond DAG: shared node visited exactly once (BFS) |
| 15 | - diamond DAG: shared node visited exactly once (DFS) |
| 16 | - BFS yields level-order (breadth before depth) |
| 17 | - DFS yields depth-first (depth before breadth) |
| 18 | - prune predicate stops subtree at matched node (node itself NOT yielded) |
| 19 | - prune at root → yields nothing |
| 20 | - exclude pre-seeds visited set (excluded nodes and subtrees skipped) |
| 21 | - max_nodes cap stops iteration after N nodes |
| 22 | - max_nodes=0 → yields nothing |
| 23 | - generic type: works with ints, not just strings |
| 24 | - multi-source starts: seeds from multiple start nodes |
| 25 | - multi-source: shared ancestor visited once |
| 26 | - adjacency returning empty → walk terminates at leaves |
| 27 | - invalid order value → raises ValueError |
| 28 | |
| 29 | iter_ancestors rewired |
| 30 | - iter_ancestors routes through walk_dag (structural check) |
| 31 | """ |
| 32 | |
| 33 | from __future__ import annotations |
| 34 | |
| 35 | from collections.abc import Iterable, Iterator |
| 36 | from typing import Callable |
| 37 | |
| 38 | import pytest |
| 39 | |
| 40 | from muse.core.graph import walk_dag |
| 41 | |
| 42 | |
| 43 | # --------------------------------------------------------------------------- |
| 44 | # Shared test graph topologies (pure in-memory dicts) |
| 45 | # --------------------------------------------------------------------------- |
| 46 | |
| 47 | # Linear: A → B → C → D |
| 48 | _LINEAR: dict[str, list[str]] = { |
| 49 | "A": ["B"], |
| 50 | "B": ["C"], |
| 51 | "C": ["D"], |
| 52 | "D": [], |
| 53 | } |
| 54 | |
| 55 | # Diamond: A → B → D |
| 56 | # A → C → D |
| 57 | _DIAMOND: dict[str, list[str]] = { |
| 58 | "A": ["B", "C"], |
| 59 | "B": ["D"], |
| 60 | "C": ["D"], |
| 61 | "D": [], |
| 62 | } |
| 63 | |
| 64 | # Wide tree: root → [L, R] |
| 65 | # L → [LL, LR] |
| 66 | # R → [RL, RR] |
| 67 | _TREE: dict[str, list[str]] = { |
| 68 | "root": ["L", "R"], |
| 69 | "L": ["LL", "LR"], |
| 70 | "R": ["RL", "RR"], |
| 71 | "LL": [], |
| 72 | "LR": [], |
| 73 | "RL": [], |
| 74 | "RR": [], |
| 75 | } |
| 76 | |
| 77 | |
| 78 | type _AdjGraph = dict[str, list[str]] |
| 79 | |
| 80 | |
| 81 | def _adj(graph: _AdjGraph) -> Callable[[str], Iterable[str]]: |
| 82 | """Return an adjacency function for a dict-based graph.""" |
| 83 | return lambda node: graph.get(node, []) |
| 84 | |
| 85 | |
| 86 | # --------------------------------------------------------------------------- |
| 87 | # Basic traversal |
| 88 | # --------------------------------------------------------------------------- |
| 89 | |
| 90 | |
| 91 | class TestWalkDagBasic: |
| 92 | def test_empty_starts_yields_nothing(self) -> None: |
| 93 | result = list(walk_dag([], _adj(_LINEAR))) |
| 94 | assert result == [] |
| 95 | |
| 96 | def test_single_node_no_neighbours(self) -> None: |
| 97 | graph = {"X": []} |
| 98 | result = list(walk_dag("X", _adj(graph))) |
| 99 | assert result == ["X"] |
| 100 | |
| 101 | def test_single_node_iterable_start(self) -> None: |
| 102 | graph = {"X": []} |
| 103 | result = list(walk_dag(["X"], _adj(graph))) |
| 104 | assert result == ["X"] |
| 105 | |
| 106 | def test_linear_chain_bfs_all_visited(self) -> None: |
| 107 | result = list(walk_dag("A", _adj(_LINEAR), order="bfs")) |
| 108 | assert set(result) == {"A", "B", "C", "D"} |
| 109 | |
| 110 | def test_linear_chain_dfs_all_visited(self) -> None: |
| 111 | result = list(walk_dag("A", _adj(_LINEAR), order="dfs")) |
| 112 | assert set(result) == {"A", "B", "C", "D"} |
| 113 | |
| 114 | def test_linear_chain_bfs_start_first(self) -> None: |
| 115 | result = list(walk_dag("A", _adj(_LINEAR), order="bfs")) |
| 116 | assert result[0] == "A" |
| 117 | |
| 118 | def test_linear_chain_dfs_start_first(self) -> None: |
| 119 | result = list(walk_dag("A", _adj(_LINEAR), order="dfs")) |
| 120 | assert result[0] == "A" |
| 121 | |
| 122 | def test_leaf_node_as_start(self) -> None: |
| 123 | """Starting from a leaf yields only that leaf.""" |
| 124 | result = list(walk_dag("D", _adj(_LINEAR))) |
| 125 | assert result == ["D"] |
| 126 | |
| 127 | def test_invalid_order_raises(self) -> None: |
| 128 | with pytest.raises(ValueError, match="order"): |
| 129 | list(walk_dag("A", _adj(_LINEAR), order="zigzag")) # type: ignore[arg-type] |
| 130 | |
| 131 | |
| 132 | # --------------------------------------------------------------------------- |
| 133 | # BFS vs DFS order |
| 134 | # --------------------------------------------------------------------------- |
| 135 | |
| 136 | |
| 137 | class TestWalkDagOrder: |
| 138 | def test_bfs_is_level_order(self) -> None: |
| 139 | """BFS on wide tree: root before L/R, L/R before leaves.""" |
| 140 | result = list(walk_dag("root", _adj(_TREE), order="bfs")) |
| 141 | root_idx = result.index("root") |
| 142 | l_idx = result.index("L") |
| 143 | r_idx = result.index("R") |
| 144 | ll_idx = result.index("LL") |
| 145 | lr_idx = result.index("LR") |
| 146 | |
| 147 | # root before both children |
| 148 | assert root_idx < l_idx |
| 149 | assert root_idx < r_idx |
| 150 | # both children before any grandchild |
| 151 | assert l_idx < ll_idx |
| 152 | assert l_idx < lr_idx |
| 153 | assert r_idx < ll_idx |
| 154 | |
| 155 | def test_dfs_is_depth_first(self) -> None: |
| 156 | """DFS on wide tree: root first, then one branch fully explored before other.""" |
| 157 | result = list(walk_dag("root", _adj(_TREE), order="dfs")) |
| 158 | root_idx = result.index("root") |
| 159 | |
| 160 | # root must be first |
| 161 | assert root_idx == 0 |
| 162 | |
| 163 | # At least one subtree's leaf comes before the other subtree's root. |
| 164 | # DFS: root → first-child branch fully → second-child branch. |
| 165 | # _TREE adjacency: root → [L, R] |
| 166 | # DFS stack pops R first, then L. So actual order depends on stack behaviour. |
| 167 | # The invariant we care about: root is first, and no interleaving of L/R subtrees. |
| 168 | l_idx = result.index("L") |
| 169 | r_idx = result.index("R") |
| 170 | ll_idx = result.index("LL") |
| 171 | lr_idx = result.index("LR") |
| 172 | |
| 173 | # Whichever branch comes first, its leaves must be before the other branch's root. |
| 174 | if l_idx < r_idx: |
| 175 | # L branch explored first |
| 176 | assert ll_idx < r_idx or lr_idx < r_idx |
| 177 | else: |
| 178 | # R branch explored first |
| 179 | rl_idx = result.index("RL") |
| 180 | rr_idx = result.index("RR") |
| 181 | assert rl_idx < l_idx or rr_idx < l_idx |
| 182 | |
| 183 | def test_bfs_vs_dfs_different_on_tree(self) -> None: |
| 184 | """BFS and DFS produce different orderings on a non-trivial tree.""" |
| 185 | bfs = list(walk_dag("root", _adj(_TREE), order="bfs")) |
| 186 | dfs = list(walk_dag("root", _adj(_TREE), order="dfs")) |
| 187 | assert set(bfs) == set(dfs) # same nodes |
| 188 | assert bfs != dfs # different order |
| 189 | |
| 190 | |
| 191 | # --------------------------------------------------------------------------- |
| 192 | # Diamond (deduplication) |
| 193 | # --------------------------------------------------------------------------- |
| 194 | |
| 195 | |
| 196 | class TestWalkDagDiamond: |
| 197 | def test_diamond_bfs_visits_shared_once(self) -> None: |
| 198 | result = list(walk_dag("A", _adj(_DIAMOND), order="bfs")) |
| 199 | assert result.count("D") == 1 |
| 200 | assert set(result) == {"A", "B", "C", "D"} |
| 201 | |
| 202 | def test_diamond_dfs_visits_shared_once(self) -> None: |
| 203 | result = list(walk_dag("A", _adj(_DIAMOND), order="dfs")) |
| 204 | assert result.count("D") == 1 |
| 205 | assert set(result) == {"A", "B", "C", "D"} |
| 206 | |
| 207 | |
| 208 | # --------------------------------------------------------------------------- |
| 209 | # prune predicate |
| 210 | # --------------------------------------------------------------------------- |
| 211 | |
| 212 | |
| 213 | class TestWalkDagPrune: |
| 214 | def test_prune_stops_at_matched_node(self) -> None: |
| 215 | """prune("B") → B and its subtree [C, D] are never yielded.""" |
| 216 | result = list(walk_dag("A", _adj(_LINEAR), prune=lambda n: n == "B")) |
| 217 | assert "A" in result |
| 218 | assert "B" not in result |
| 219 | assert "C" not in result |
| 220 | assert "D" not in result |
| 221 | |
| 222 | def test_prune_at_root_yields_nothing(self) -> None: |
| 223 | """Pruning the start node itself → nothing yielded.""" |
| 224 | result = list(walk_dag("A", _adj(_LINEAR), prune=lambda n: n == "A")) |
| 225 | assert result == [] |
| 226 | |
| 227 | def test_prune_at_leaf_no_effect(self) -> None: |
| 228 | """Pruning a leaf doesn't affect earlier nodes.""" |
| 229 | result = set(walk_dag("A", _adj(_LINEAR), prune=lambda n: n == "D")) |
| 230 | assert result == {"A", "B", "C"} |
| 231 | |
| 232 | def test_prune_one_branch_of_diamond(self) -> None: |
| 233 | """Pruning B in diamond: C path still reaches D; B subtree skipped.""" |
| 234 | # A → B (pruned), A → C → D |
| 235 | result = list(walk_dag("A", _adj(_DIAMOND), prune=lambda n: n == "B")) |
| 236 | assert "A" in result |
| 237 | assert "B" not in result |
| 238 | assert "C" in result |
| 239 | assert "D" in result # D reachable via C |
| 240 | |
| 241 | def test_prune_both_branches_of_diamond(self) -> None: |
| 242 | """Pruning both B and C → D never reached.""" |
| 243 | result = list(walk_dag("A", _adj(_DIAMOND), prune=lambda n: n in {"B", "C"})) |
| 244 | assert result == ["A"] |
| 245 | |
| 246 | |
| 247 | # --------------------------------------------------------------------------- |
| 248 | # exclude |
| 249 | # --------------------------------------------------------------------------- |
| 250 | |
| 251 | |
| 252 | class TestWalkDagExclude: |
| 253 | def test_exclude_pre_seeds_visited(self) -> None: |
| 254 | """Excluded nodes are treated as already-visited; not yielded.""" |
| 255 | result = list(walk_dag("A", _adj(_LINEAR), exclude={"B"})) |
| 256 | assert "A" in result |
| 257 | assert "B" not in result |
| 258 | assert "C" not in result # C only reachable via B |
| 259 | assert "D" not in result |
| 260 | |
| 261 | def test_exclude_start_node_yields_nothing(self) -> None: |
| 262 | """Excluding the start node → nothing yielded (start treated as visited).""" |
| 263 | result = list(walk_dag("A", _adj(_LINEAR), exclude={"A"})) |
| 264 | assert result == [] |
| 265 | |
| 266 | def test_exclude_leaf(self) -> None: |
| 267 | """Excluding a leaf: other nodes still visited.""" |
| 268 | result = set(walk_dag("A", _adj(_LINEAR), exclude={"D"})) |
| 269 | assert result == {"A", "B", "C"} |
| 270 | |
| 271 | def test_exclude_does_not_mutate_input(self) -> None: |
| 272 | """walk_dag must not mutate the caller's exclude set.""" |
| 273 | excl: set[str] = set() |
| 274 | list(walk_dag("A", _adj(_LINEAR), exclude=excl)) |
| 275 | assert excl == set() |
| 276 | |
| 277 | |
| 278 | # --------------------------------------------------------------------------- |
| 279 | # max_nodes cap |
| 280 | # --------------------------------------------------------------------------- |
| 281 | |
| 282 | |
| 283 | class TestWalkDagMaxNodes: |
| 284 | def test_max_nodes_zero_yields_nothing(self) -> None: |
| 285 | result = list(walk_dag("A", _adj(_LINEAR), max_nodes=0)) |
| 286 | assert result == [] |
| 287 | |
| 288 | def test_max_nodes_one_yields_start(self) -> None: |
| 289 | result = list(walk_dag("A", _adj(_LINEAR), max_nodes=1)) |
| 290 | assert result == ["A"] |
| 291 | |
| 292 | def test_max_nodes_caps_count(self) -> None: |
| 293 | result = list(walk_dag("A", _adj(_LINEAR), max_nodes=2)) |
| 294 | assert len(result) == 2 |
| 295 | |
| 296 | def test_max_nodes_larger_than_graph(self) -> None: |
| 297 | """max_nodes larger than the graph → all nodes yielded normally.""" |
| 298 | result = list(walk_dag("A", _adj(_LINEAR), max_nodes=999)) |
| 299 | assert set(result) == {"A", "B", "C", "D"} |
| 300 | |
| 301 | |
| 302 | # --------------------------------------------------------------------------- |
| 303 | # Generic type (ints) |
| 304 | # --------------------------------------------------------------------------- |
| 305 | |
| 306 | |
| 307 | class TestWalkDagGenericType: |
| 308 | def test_works_with_integers(self) -> None: |
| 309 | """walk_dag is generic — must work with int nodes, not just strings.""" |
| 310 | graph: dict[int, list[int]] = {1: [2, 3], 2: [4], 3: [4], 4: []} |
| 311 | result = list(walk_dag(1, lambda n: graph.get(n, []))) |
| 312 | assert set(result) == {1, 2, 3, 4} |
| 313 | assert result.count(4) == 1 # shared node visited once |
| 314 | |
| 315 | def test_works_with_tuples(self) -> None: |
| 316 | """Nodes can be any hashable — tuples work fine (wrap in list to start).""" |
| 317 | graph: dict[tuple[int, int], list[tuple[int, int]]] = { |
| 318 | (0, 0): [(1, 0), (0, 1)], |
| 319 | (1, 0): [], |
| 320 | (0, 1): [], |
| 321 | } |
| 322 | result = list(walk_dag([(0, 0)], lambda n: graph.get(n, []))) |
| 323 | assert set(result) == {(0, 0), (1, 0), (0, 1)} |
| 324 | |
| 325 | |
| 326 | # --------------------------------------------------------------------------- |
| 327 | # Multi-source starts |
| 328 | # --------------------------------------------------------------------------- |
| 329 | |
| 330 | |
| 331 | class TestWalkDagMultiSource: |
| 332 | def test_multi_source_visits_all_reachable(self) -> None: |
| 333 | graph: dict[str, list[str]] = { |
| 334 | "shared": [], |
| 335 | "a": ["shared"], |
| 336 | "b": ["shared"], |
| 337 | } |
| 338 | result = list(walk_dag(["a", "b"], _adj(graph))) |
| 339 | assert set(result) == {"a", "b", "shared"} |
| 340 | |
| 341 | def test_multi_source_shared_ancestor_once(self) -> None: |
| 342 | graph: dict[str, list[str]] = { |
| 343 | "shared": [], |
| 344 | "a": ["shared"], |
| 345 | "b": ["shared"], |
| 346 | } |
| 347 | result = list(walk_dag(["a", "b"], _adj(graph))) |
| 348 | assert result.count("shared") == 1 |
| 349 | |
| 350 | def test_multi_source_exclude_applies_to_all(self) -> None: |
| 351 | graph: dict[str, list[str]] = { |
| 352 | "shared": [], |
| 353 | "a": ["shared"], |
| 354 | "b": ["shared"], |
| 355 | } |
| 356 | result = list(walk_dag(["a", "b"], _adj(graph), exclude={"shared"})) |
| 357 | assert "shared" not in result |
| 358 | assert set(result) == {"a", "b"} |
| 359 | |
| 360 | |
| 361 | # --------------------------------------------------------------------------- |
| 362 | # Structural: iter_ancestors routes through walk_dag |
| 363 | # --------------------------------------------------------------------------- |
| 364 | |
| 365 | |
| 366 | class TestIterAncestorsRoutesThroughWalkDag: |
| 367 | def test_iter_ancestors_calls_walk_dag(self) -> None: |
| 368 | """iter_ancestors must delegate to walk_dag (implementation check).""" |
| 369 | import inspect |
| 370 | from muse.core import graph as graph_module |
| 371 | |
| 372 | source = inspect.getsource(graph_module.iter_ancestors) |
| 373 | assert "walk_dag" in source, ( |
| 374 | "iter_ancestors must call walk_dag after Phase 1 refactor" |
| 375 | ) |
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fix: remove commit_exists filter from have anchors — server…
Sonnet 4.6
patch
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