refactor: drop environment expansion

Expansion of project environment is now done in craft-application;
reorganize the code so that we still do Rockcraft-specific
transformations (apply extensions and add the Pebble part), but we
can remove the expansion-related code.

rockcraft/application.py

@@ -18,10 +18,8 @@
 
 from __future__ import annotations
 
-import functools
-import pathlib
+from typing import Any
 
-import craft_cli
 from craft_application import Application, AppMetadata, util
 from overrides import override
 
@@ -39,12 +37,9 @@
 class Rockcraft(Application):
     """Rockcraft application definition."""
 
-    @functools.cached_property
-    def project(self) -> models.Project:
-        """Get this application's Project metadata."""
-        project_file = (pathlib.Path.cwd() / f"{self.app.name}.yaml").resolve()
-        craft_cli.emit.debug(f"Loading project file '{project_file!s}'")
-        return models.Project.from_yaml_file(project_file, work_dir=self._work_dir)
+    @override
+    def _extra_yaml_transform(self, yaml_data: dict[str, Any]) -> dict[str, Any]:
+        return models.transform_yaml(self._work_dir, yaml_data)
 
     @override
     def _configure_services(self, platform: str | None, build_for: str | None) -> None:

rockcraft/models/__init__.py

@@ -17,6 +17,11 @@
 """Rockcraft models."""
 
 
-from rockcraft.models.project import Project, RockcraftBuildInfo, load_project
+from rockcraft.models.project import (
+    Project,
+    RockcraftBuildInfo,
+    load_project,
+    transform_yaml,
+)
 
-__all__ = ["Project", "RockcraftBuildInfo", "load_project"]
+__all__ = ["Project", "RockcraftBuildInfo", "load_project", "transform_yaml"]

rockcraft/models/project.py

@@ -17,7 +17,6 @@
 """Project definition and helpers."""
 import dataclasses
 import operator
-import pathlib
 import platform as host_platform
 import re
 from builtins import super
@@ -40,15 +39,12 @@
 import pydantic
 import spdx_lookup  # type: ignore
 import yaml
-from craft_application.errors import CraftValidationError
 from craft_application.models import BuildInfo
 from craft_application.models import Project as BaseProject
 from craft_archives import repo
 from craft_providers import bases
-from overrides import override
 from pydantic_yaml import YamlModelMixin
 
-from rockcraft.environment import expand_environment
 from rockcraft.errors import ProjectLoadError, ProjectValidationError
 from rockcraft.extensions import apply_extensions
 from rockcraft.parts import part_has_overlay, validate_part
@@ -487,29 +483,6 @@ def unmarshal(cls, data: Dict[str, Any]) -> "Project":
 
         return project
 
-    @classmethod
-    @override
-    def from_yaml_file(
-        cls, path: pathlib.Path, *, work_dir: Optional[pathlib.Path] = None
-    ) -> "Project":
-        """Instantiate this model from a YAML file."""
-        # pylint: disable=import-outside-toplevel
-
-        data = load_project(path)
-
-        if work_dir is not None:
-            project_vars = {"version": data["version"]}
-            expand_environment(
-                data,
-                project_vars=project_vars,
-                work_dir=work_dir,
-            )
-        try:
-            # TODO apply extensions here
-            return cls.unmarshal(data)
-        except pydantic.ValidationError as err:
-            raise CraftValidationError.from_pydantic(err, file_name=path.name) from None
-
     def generate_metadata(
         self, generation_time: str, base_digest: bytes
     ) -> Tuple[dict, dict]:
@@ -679,7 +652,17 @@ def load_project(filename: Path) -> Dict[str, Any]:
             msg = f"{msg}: {err.filename!r}."
         raise ProjectLoadError(msg) from err
 
-    yaml_data = apply_extensions(filename.parent, yaml_data)
+    yaml_data = transform_yaml(filename.parent, yaml_data)
+    return yaml_data
+
+
+def transform_yaml(project_root: Path, yaml_data: Dict[str, Any]) -> Dict[str, Any]:
+    """Do Rockcraft-specific transformations on a project yaml.
+
+    :param project_root: The path that contains the "rockcraft.yaml" file.
+    :param yaml_data: The data dict loaded from the yaml file.
+    """
+    yaml_data = apply_extensions(project_root, yaml_data)
 
     _add_pebble_data(yaml_data)
 

tests/unit/extensions/test_extensions.py

@@ -17,7 +17,7 @@
 import pytest
 
 from rockcraft import errors, extensions
-from rockcraft.models.project import load_project
+from rockcraft.models import load_project
 from tests.unit.testing.extensions import (
     FULL_EXTENSION_YAML,
     ExperimentalExtension,

tests/unit/test_application.py

@@ -15,6 +15,8 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 from pathlib import Path
 
+from rockcraft.pebble import Pebble
+
 ENVIRONMENT_YAML = """\
 name: environment-test
 version: 2.0
@@ -53,3 +55,12 @@ def test_application_expand_environment(default_application, new_dir):
         "X": "ship it!",
         "CRAFT_VAR": "2.0",
     }
+
+
+def test_application_pebble_part(default_application, new_dir):
+    """Test that loading the project through the application adds the Pebble part."""
+    project_file = Path(new_dir) / "rockcraft.yaml"
+    project_file.write_text(ENVIRONMENT_YAML)
+
+    project = default_application.project
+    assert project.parts["pebble"] == Pebble.PEBBLE_PART_SPEC