feat(yarn_classic): implement 'Project' class

## What

- a class representing a yarn project
- can create Projects from a source dir
- can check for (disallowed) PnP installs

## How

- implement `Project` as a frozen dataclass

Signed-off-by: Ben Alkov <[email protected]>

cachi2/core/package_managers/yarn_classic/main.py

@@ -1,13 +1,14 @@
 import logging
 
-from cachi2.core.errors import PackageManagerError
+from cachi2.core.errors import PackageManagerError, PackageRejected
 from cachi2.core.models.input import Request
 from cachi2.core.models.output import Component, EnvironmentVariable, RequestOutput
 from cachi2.core.package_managers.yarn.utils import (
     VersionsRange,
     extract_yarn_version_from_env,
     run_yarn_cmd,
 )
+from cachi2.core.package_managers.yarn_classic.project import Project
 from cachi2.core.package_managers.yarn_classic.workspaces import extract_workspace_metadata
 from cachi2.core.rooted_path import RootedPath
 
@@ -91,6 +92,24 @@ def _generate_build_environment_variables() -> list[EnvironmentVariable]:
     return [EnvironmentVariable(name=key, value=value) for key, value in env_vars.items()]
 
 
+def _reject_if_pnp_install(project: Project) -> None:
+    if project.is_pnp_install:
+        raise PackageRejected(
+            reason=("Yarn PnP install detected; PnP installs are unsupported by cachi2"),
+            solution=(
+                "Please convert your project to a regular install-based one.\n"
+                "If you use Yarn's PnP, please remove `installConfig.pnp: true`"
+                " from 'package.json', any file(s) with glob name '*.pnp.cjs',"
+                " and any 'node_modules' directories."
+            ),
+        )
+
+
+def _verify_repository(project: Project) -> None:
+    _reject_if_pnp_install(project)
+    # _check_lockfile(project)
+
+
 def _verify_corepack_yarn_version(source_dir: RootedPath, env: dict[str, str]) -> None:
     """Verify that corepack installed the correct version of yarn by checking `yarn --version`."""
     installed_yarn_version = extract_yarn_version_from_env(source_dir, env)

cachi2/core/package_managers/yarn_classic/project.py

@@ -92,3 +92,32 @@ def from_file(cls, path: RootedPath) -> "PackageJson":
 
 
 ConfigFile = Union[PackageJson]
+
+
+@dataclass(frozen=True)
+class Project:
+    """Minimally, a directory containing yarn sources and parsed package.json."""
+
+    source_dir: RootedPath
+    package_json: PackageJson
+
+    @property
+    def is_pnp_install(self) -> bool:
+        """Is the project is using Plug'n'Play (PnP) workflow or not.
+
+        This is determined by
+        - `installConfig.pnp: true` in 'package.json'
+        - the existence of file(s) with glob name '*.pnp.cjs'
+        - the presence of an expanded node_modules directory
+        For more details on PnP, see: https://classic.yarnpkg.com/en/docs/pnp
+        """
+        install_config_pnp_enabled = self.package_json.install_config.get("pnp", False)
+        pnp_cjs_exists = any(self.source_dir.path.glob("*.pnp.cjs"))
+        node_modules_exists = self.source_dir.join_within_root("node_modules").path.exists()
+        return install_config_pnp_enabled or pnp_cjs_exists or node_modules_exists
+
+    @classmethod
+    def from_source_dir(cls, source_dir: RootedPath) -> "Project":
+        """Create a Project from a sources directory path."""
+        package_json = PackageJson.from_file(source_dir.join_within_root("package.json"))
+        return cls(source_dir, package_json)

tests/unit/package_managers/yarn_classic/test_project.py

@@ -3,7 +3,8 @@
 import pytest
 
 from cachi2.core.errors import PackageRejected
-from cachi2.core.package_managers.yarn_classic.project import ConfigFile, PackageJson
+from cachi2.core.package_managers.yarn_classic.main import _verify_repository
+from cachi2.core.package_managers.yarn_classic.project import ConfigFile, PackageJson, Project
 from cachi2.core.rooted_path import RootedPath
 
 VALID_PACKAGE_JSON_FILE = """
@@ -37,6 +38,13 @@ def _prepare_config_file(
     return config_file_class.from_file(path)
 
 
+def _setup_pnp_installs(rooted_tmp_path: RootedPath, pnp_kind: str) -> None:
+    if pnp_kind == "node":
+        rooted_tmp_path.join_within_root("node_modules").path.mkdir()
+    if pnp_kind == "pnp_cjs":
+        rooted_tmp_path.join_within_root("foo.pnp.cjs").path.touch()
+
+
 @pytest.mark.parametrize(
     "config_file_class, config_file_name, config_file_content, config_kind",
     [
@@ -132,3 +140,66 @@ def test_from_file_missing(
     with pytest.raises(PackageRejected):
         path = rooted_tmp_path.join_within_root(config_file_name)
         config_file_class.from_file(path)
+
+
+@pytest.mark.parametrize(
+    "config_file_class, config_file_name, config_file_content, pnp_kind",
+    [
+        pytest.param(
+            PackageJson,
+            "package.json",
+            PNP_PACKAGE_JSON_FILE,
+            "install_config",
+            id="installConfig",
+        ),
+        pytest.param(PackageJson, "package.json", VALID_PACKAGE_JSON_FILE, "node", id="node"),
+        pytest.param(PackageJson, "package.json", VALID_PACKAGE_JSON_FILE, "pnp_cjs", id="pnp_cjs"),
+    ],
+)
+def test_pnp_installs_true(
+    rooted_tmp_path: RootedPath,
+    config_file_class: ConfigFile,
+    config_file_name: str,
+    config_file_content: str,
+    pnp_kind: str,
+) -> None:
+    _prepare_config_file(
+        rooted_tmp_path,
+        config_file_class,
+        config_file_name,
+        config_file_content,
+    )
+
+    project = Project.from_source_dir(rooted_tmp_path)
+
+    _setup_pnp_installs(rooted_tmp_path, pnp_kind)
+    with pytest.raises(PackageRejected):
+        _verify_repository(project)
+
+
+@pytest.mark.parametrize(
+    "config_file_class, config_file_name, config_file_content",
+    [
+        pytest.param(
+            PackageJson,
+            "package.json",
+            VALID_PACKAGE_JSON_FILE,
+        ),
+    ],
+)
+def test_pnp_installs_false(
+    rooted_tmp_path: RootedPath,
+    config_file_class: ConfigFile,
+    config_file_name: str,
+    config_file_content: str,
+) -> None:
+    _prepare_config_file(
+        rooted_tmp_path,
+        config_file_class,
+        config_file_name,
+        config_file_content,
+    )
+
+    project = Project.from_source_dir(rooted_tmp_path)
+
+    _verify_repository(project)