Merge pull request #13230 from notatallshaw/add-unit-tests-for-PipPro…

…vider.get_preference

`PipProvider.get_preference` unit tests

tests/unit/resolution_resolvelib/test_provider.py

@@ -0,0 +1,109 @@
+import math
+from typing import TYPE_CHECKING, Dict, Iterable, Optional, Sequence
+
+import pytest
+
+from pip._vendor.resolvelib.resolvers import RequirementInformation
+
+from pip._internal.req.constructors import install_req_from_req_string
+from pip._internal.resolution.resolvelib.base import Candidate
+from pip._internal.resolution.resolvelib.candidates import REQUIRES_PYTHON_IDENTIFIER
+from pip._internal.resolution.resolvelib.factory import Factory
+from pip._internal.resolution.resolvelib.provider import PipProvider
+from pip._internal.resolution.resolvelib.requirements import SpecifierRequirement
+
+if TYPE_CHECKING:
+    from pip._vendor.resolvelib.providers import Preference
+
+    from pip._internal.resolution.resolvelib.base import Candidate, Requirement
+
+    PreferenceInformation = RequirementInformation[Requirement, Candidate]
+
+
+def build_req_info(
+    name: str, parent: Optional[Candidate] = None
+) -> "PreferenceInformation":
+    install_requirement = install_req_from_req_string(name)
+
+    requirement_information: PreferenceInformation = RequirementInformation(
+        requirement=SpecifierRequirement(install_requirement),
+        parent=parent,
+    )
+
+    return requirement_information
+
+
+@pytest.mark.parametrize(
+    "identifier, information, backtrack_causes, user_requested, expected",
+    [
+        # Test case for REQUIRES_PYTHON_IDENTIFIER
+        (
+            REQUIRES_PYTHON_IDENTIFIER,
+            {REQUIRES_PYTHON_IDENTIFIER: [build_req_info("python")]},
+            [],
+            {},
+            (False, False, True, True, math.inf, True, REQUIRES_PYTHON_IDENTIFIER),
+        ),
+        # Pinned package with "=="
+        (
+            "pinned-package",
+            {"pinned-package": [build_req_info("pinned-package==1.0")]},
+            [],
+            {},
+            (True, False, False, True, math.inf, False, "pinned-package"),
+        ),
+        # Package that caused backtracking
+        (
+            "backtrack-package",
+            {"backtrack-package": [build_req_info("backtrack-package")]},
+            [build_req_info("backtrack-package")],
+            {},
+            (True, False, True, False, math.inf, True, "backtrack-package"),
+        ),
+        # Root package requested by user
+        (
+            "root-package",
+            {"root-package": [build_req_info("root-package")]},
+            [],
+            {"root-package": 1},
+            (True, False, True, True, 1, True, "root-package"),
+        ),
+        # Unfree package (with specifier operator)
+        (
+            "unfree-package",
+            {"unfree-package": [build_req_info("unfree-package<1")]},
+            [],
+            {},
+            (True, False, True, True, math.inf, False, "unfree-package"),
+        ),
+        # Free package (no operator)
+        (
+            "free-package",
+            {"free-package": [build_req_info("free-package")]},
+            [],
+            {},
+            (True, False, True, True, math.inf, True, "free-package"),
+        ),
+    ],
+)
+def test_get_preference(
+    identifier: str,
+    information: Dict[str, Iterable["PreferenceInformation"]],
+    backtrack_causes: Sequence["PreferenceInformation"],
+    user_requested: Dict[str, int],
+    expected: "Preference",
+    factory: Factory,
+) -> None:
+    provider = PipProvider(
+        factory=factory,
+        constraints={},
+        ignore_dependencies=False,
+        upgrade_strategy="to-satisfy-only",
+        user_requested=user_requested,
+    )
+
+    preference = provider.get_preference(
+        identifier, {}, {}, information, backtrack_causes
+    )
+
+    assert preference == expected, f"Expected {expected}, got {preference}"