chore(project): implement _providers_base()

Signed-off-by: Callahan Kovacs <callahan.kovacs@canonical.com>

snapcraft/models/project.py

@@ -44,6 +44,7 @@
 from craft_grammar.models import GrammarSingleEntryDictList, GrammarStr, GrammarStrList
 from craft_providers import bases
 from pydantic import PrivateAttr, constr
+from typing_extensions import override
 
 from snapcraft import utils
 from snapcraft.const import SUPPORTED_ARCHS, SnapArch
@@ -602,6 +603,22 @@ class Project(models.Project):
     provenance: Optional[str]
     components: Optional[Dict[ProjectName, Component]]
 
+    @override
+    @classmethod
+    def _providers_base(cls, base: str) -> bases.BaseAlias | None:
+        """Get a BaseAlias from snapcraft's base.
+        :param base: The application-specific base name.
+        :returns: The BaseAlias for the base.
+        :raises CraftValidationError: If the project's base cannot be determined.
+        """
+        if base == "bare":
+            return None
+
+        try:
+            return SNAPCRAFT_BASE_TO_PROVIDER_BASE[base]
+        except KeyError as err:
+            raise CraftValidationError(f"Unknown base {base!r}") from err
+
     @pydantic.validator("plugs")
     @classmethod
     def _validate_plugs(cls, plugs):

tests/unit/models/test_projects.py

@@ -24,7 +24,7 @@
 from craft_providers.bases import BaseName
 
 import snapcraft.models
-from snapcraft import const, errors
+from snapcraft import const, errors, providers
 from snapcraft.models import (
     MANDATORY_ADOPTABLE_FIELDS,
     Architecture,
@@ -585,6 +585,21 @@ def test_project_build_base_devel_grade_stable_error(self, project_yaml_data):
         with pytest.raises(errors.ProjectValidationError, match=error):
             Project.unmarshal(project_yaml_data(build_base="devel", grade="stable"))
 
+    @pytest.mark.parametrize(
+        ("base", "expected_base"),
+        [("bare", None), *providers.SNAPCRAFT_BASE_TO_PROVIDER_BASE.items()],
+    )
+    def test_provider_base(self, base, expected_base, project_yaml_data):
+        providers_base = Project._providers_base(base)
+
+        assert providers_base == expected_base
+
+    def test_provider_base_error(self, project_yaml_data):
+        with pytest.raises(CraftValidationError) as raised:
+            Project._providers_base("unknown")
+
+        assert "Unknown base 'unknown'" in str(raised.value)
+
     def test_project_global_plugs_warning(self, project_yaml_data, emitter):
         data = project_yaml_data(plugs={"desktop": None, "desktop-legacy": None})
         Project.unmarshal(data)