Initial pacman code

tests/test_decman_plugins_pacman_resolver.py

@@ -0,0 +1,88 @@
+import pytest
+
+from decman.plugins.pacman.error import DependencyCycleError
+from decman.plugins.pacman.resolver import DepGraph, ForeignPackage
+
+
+def test_add_dependency():
+    graph = DepGraph()
+
+    graph.add_requirement("A", None)
+    graph.add_requirement("B1", "A")
+    graph.add_requirement("B2", "A")
+    graph.add_requirement("C", "B1")
+
+    assert "B1" in graph.package_nodes["A"].children
+    assert "B2" in graph.package_nodes["A"].children
+    assert "C" in graph.package_nodes["B1"].children
+
+
+def test_cyclic_dependency_raises():
+    graph = DepGraph()
+
+    graph.add_requirement("A", None)
+    graph.add_requirement("B", "A")
+    graph.add_requirement("C", "B")
+
+    with pytest.raises(DependencyCycleError):
+        graph.add_requirement("A", "C")
+
+
+def _build_graph_for_outer_deps() -> DepGraph:
+    graph = DepGraph()
+
+    # Roots
+    graph.add_requirement("A", None)
+    graph.add_requirement("V", None)
+
+    # Level B
+    graph.add_requirement("B1", "A")
+    graph.add_requirement("B2", "A")
+    graph.add_requirement("B3", "A")
+
+    # Extra dependency B1 -> B2
+    graph.add_requirement("B1", "B2")
+
+    # Level C
+    graph.add_requirement("C1", "B1")
+    graph.add_requirement("C2", "B1")
+
+    # Level D + cycle-ish edges
+    graph.add_requirement("D", "C1")
+    graph.add_requirement("C2", "D")
+
+    # Foreign packages and their foreign deps
+    defs = {
+        "V": [],
+        "A": ["B1", "B2", "B3", "C1", "C2", "D"],
+        "B1": ["C1", "C2", "D"],
+        "B2": ["B1", "C1", "C2", "D"],
+        "B3": [],
+        "C1": ["D", "C2"],
+        "C2": [],
+        "D": ["C2"],
+    }
+
+    for name, deps in defs.items():
+        pkg = ForeignPackage(name)
+        pkg.add_foreign_dependency_packages(deps)
+
+    return graph
+
+
+def _assert_outer_dep_names(graph: DepGraph, expected: set[str]) -> None:
+    result = graph.get_and_remove_outer_dep_pkgs()
+    names = {pkg.name for pkg in result}
+    assert names == expected
+
+
+def test_get_and_remove_outer_deps_sequence():
+    graph = _build_graph_for_outer_deps()
+
+    _assert_outer_dep_names(graph, {"C2", "B3", "V"})
+    _assert_outer_dep_names(graph, {"D"})
+    _assert_outer_dep_names(graph, {"C1"})
+    _assert_outer_dep_names(graph, {"B1"})
+    _assert_outer_dep_names(graph, {"B2"})
+    _assert_outer_dep_names(graph, {"A"})
+    _assert_outer_dep_names(graph, set())