feat [WIP]: add strategy=lowest

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "poetry"
-version = "1.9.0.dev0"
+version = "1.9.0.dev1"
 description = "Python dependency management and packaging made easy."
 authors = ["Sébastien Eustace <sebastien@eustace.io>"]
 maintainers = [

src/poetry/console/commands/lock.py

@@ -6,6 +6,7 @@
 from cleo.helpers import option
 
 from poetry.console.commands.installer_command import InstallerCommand
+from poetry.installation import Strategy
 
 
 if TYPE_CHECKING:
@@ -27,6 +28,14 @@ class LockCommand(InstallerCommand):
             " version of <comment>pyproject.toml</>. (<warning>Deprecated</>) Use"
             " <comment>poetry check --lock</> instead.",
         ),
+        option(
+            "strategy",
+            None,
+            "Lock dependencies using a dependency resolution strategy.",
+            value_required=True,
+            default="latest",
+            flag=False,
+        ),
     ]
 
     help = """
@@ -57,6 +66,15 @@ def handle(self) -> int:
             )
             return 1
 
+        if strategy := self.option("strategy"):
+            if strategy not in [s.value for s in Strategy]:
+                self.line_error(
+                    f"<error> Invalid strategy '{strategy}'. Valid strategies are: "
+                    f"{', '.join([s.value for s in Strategy])}"
+                    "</error>"
+                )
+                return 1
+            self.installer.strategy = strategy
         self.installer.lock(update=not self.option("no-update"))
 
         return self.installer.run()

src/poetry/installation/__init__.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from poetry.installation.installer import Installer
+from poetry.installation.strategy import Strategy
 
 
-__all__ = ["Installer"]
+__all__ = ["Installer", "Strategy"]

src/poetry/installation/installer.py

@@ -9,6 +9,7 @@
 from poetry.installation.executor import Executor
 from poetry.installation.operations import Uninstall
 from poetry.installation.operations import Update
+from poetry.installation.strategy import Strategy
 from poetry.repositories import Repository
 from poetry.repositories import RepositoryPool
 from poetry.repositories.installed_repository import InstalledRepository
@@ -20,7 +21,6 @@
 
     from cleo.io.io import IO
     from packaging.utils import NormalizedName
-    from poetry.core.packages.path_dependency import PathDependency
     from poetry.core.packages.project_package import ProjectPackage
 
     from poetry.config.config import Config
@@ -41,13 +41,15 @@ def __init__(
         installed: Repository | None = None,
         executor: Executor | None = None,
         disable_cache: bool = False,
+        strategy: Strategy = Strategy.LATEST,
     ) -> None:
         self._io = io
         self._env = env
         self._package = package
         self._locker = locker
         self._pool = pool
         self._config = config
+        self.strategy = strategy
 
         self._dry_run = False
         self._requires_synchronization = False
@@ -185,6 +187,7 @@ def _do_refresh(self) -> int:
             locked_repository.packages,
             locked_repository.packages,
             self._io,
+            Strategy.is_using_lowest(self.strategy),
         )
 
         # Always re-solve directory dependencies, otherwise we can't determine
@@ -231,6 +234,7 @@ def _do_install(self) -> int:
                 self._installed_repository.packages,
                 locked_repository.packages,
                 self._io,
+                Strategy.is_using_lowest(self.strategy),
             )
 
             with solver.provider.use_source_root(
@@ -287,6 +291,7 @@ def _do_install(self) -> int:
             self._installed_repository.packages,
             locked_repository.packages,
             NullIO(),
+            Strategy.is_using_lowest(self.strategy),
         )
         # Everything is resolved at this point, so we no longer need
         # to load deferred dependencies (i.e. VCS, URL and path dependencies)
@@ -304,7 +309,7 @@ def _do_install(self) -> int:
         for op in ops:
             dep = op.package.to_dependency()
             if dep.is_file() or dep.is_directory():
-                dep = cast("PathDependency", dep)
+                dep = cast("PathDependency", dep)  # noqa: F821
                 dep.validate(raise_error=not op.skipped)
 
         # Execute operations

src/poetry/installation/strategy.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from enum import Enum
+
+
+class Strategy(Enum):
+    LATEST = "latest"
+    LOWEST = "lowest"
+
+    @classmethod
+    def is_using_lowest(cls, other: Strategy | str) -> bool:
+        if isinstance(other, cls):
+            return other == cls.LOWEST
+        else:
+            return other == "lowest"

src/poetry/puzzle/provider.py

@@ -117,6 +117,7 @@ def __init__(
         *,
         installed: list[Package] | None = None,
         locked: list[Package] | None = None,
+        use_lowest: bool = False,
     ) -> None:
         self._package = package
         self._pool = pool
@@ -133,16 +134,18 @@ def __init__(
         self._direct_origin_packages: dict[str, Package] = {}
         self._locked: dict[NormalizedName, list[DependencyPackage]] = defaultdict(list)
         self._use_latest: Collection[NormalizedName] = []
+        self._use_lowest = use_lowest
 
         self._explicit_sources: dict[str, str] = {}
         for package in locked or []:
             self._locked[package.name].append(
                 DependencyPackage(package.to_dependency(), package)
             )
         for dependency_packages in self._locked.values():
+            # prioritize resolving by lowest versions if use_lowest is True
             dependency_packages.sort(
                 key=lambda p: p.package.version,
-                reverse=True,
+                reverse=not use_lowest,
             )
 
     @property

src/poetry/puzzle/solver.py

@@ -41,15 +41,22 @@ def __init__(
         installed: list[Package],
         locked: list[Package],
         io: IO,
+        use_lowest: bool = False,
     ) -> None:
         self._package = package
         self._pool = pool
         self._installed_packages = installed
         self._locked_packages = locked
         self._io = io
+        self._lowest = use_lowest
 
         self._provider = Provider(
-            self._package, self._pool, self._io, installed=installed, locked=locked
+            self._package,
+            self._pool,
+            self._io,
+            installed=installed,
+            locked=locked,
+            use_lowest=self._lowest,
         )
         self._overrides: list[dict[Package, dict[str, Dependency]]] = []
 

tests/installation/test_strategy.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+import pytest
+
+from poetry.installation import Strategy
+
+
+@pytest.mark.parametrize("strategy", ["lowest", Strategy.LOWEST])
+def test_is_using_lowest_true(strategy):
+    assert Strategy.is_using_lowest(strategy)
+
+
+@pytest.mark.parametrize("strategy", ["latest", Strategy.LATEST])
+def test_is_using_lowest_false(strategy):
+    assert not Strategy.is_using_lowest(strategy)