Implement fetching dependencies for yarn regular workflow

* with new custom YarnCommandError
* covered with unit tests

JIRA: STONEBLD-1788

Signed-off-by: Michal Šoltis <[email protected]>

cachi2/core/errors.py

@@ -112,3 +112,17 @@ class GoModError(Cachi2Error):
         The output of the failing go command should provide more details, please check the logs.
         """
     ).strip()
+
+
+class YarnCommandError(Cachi2Error):
+    """The 'yarn' command used while processing a Yarn project returned an error."""
+
+    default_solution = textwrap.dedent(
+        """
+        The cause of the failure could be:
+        - something is broken in Cachi2
+        - something is wrong with your yarn project
+        - communication with an external service failed (please try again)
+        The output of the failing yarn command should provide more details, please check the logs.
+        """
+    ).strip()

cachi2/core/package_managers/yarn/main.py

@@ -7,6 +7,7 @@
     create_component_from_package,
     resolve_packages,
 )
+from cachi2.core.package_managers.yarn.utils import run_yarn_cmd
 from cachi2.core.rooted_path import RootedPath
 
 log = logging.getLogger(__name__)
@@ -73,7 +74,7 @@ def _check_yarn_cache(source_dir: RootedPath) -> None:
     """Check the contents of the yarn cache using 'yarn install'.
 
     :param source_dir: the directory in which the yarn command will be called.
-    :raises SubprocessCallError: if the 'yarn install' command fails.
+    :raises YarnCommandError: if the 'yarn install' command fails.
     """
     # the yarn commands can be called by using the core.utils.run_cmd function
     pass
@@ -84,11 +85,12 @@ def _fetch_dependencies(source_dir: RootedPath, output_dir: RootedPath) -> None:
 
     :param source_dir: the directory in which the yarn command will be called.
     :param output_dir: the directory where the yarn dependencies will be downloaded to.
-    :raises SubprocessCallError: if the 'yarn install' command fails.
+    :raises YarnCommandError: if the 'yarn install' command fails.
     """
-    # the output_dir is where the globalFolder must be set to
-    # the yarn commands can be called by using the core.utils.run_cmd function
-    pass
+    cachi2_output = output_dir.join_within_root("deps", "yarn")
+
+    args = ["install", "--mode", "skip-build"]
+    run_yarn_cmd(args, source_dir, {"YARN_GLOBAL_FOLDER": str(cachi2_output)})
 
 
 def _undo_changes(project: Project) -> None:

cachi2/core/package_managers/yarn/resolver.py

@@ -52,7 +52,7 @@ def resolve_packages(source_dir: RootedPath) -> list[Package]:
     processed.
 
     :raises PackageRejected: if the validation fails.
-    :raises SubprocessCallError: if the 'yarn info' command fails.
+    :raises YarnCommandError: if the 'yarn info' command fails.
     """
     under_development = True
     if under_development:

cachi2/core/package_managers/yarn/utils.py

@@ -1,3 +1,6 @@
+import subprocess  # nosec
+
+from cachi2.core.errors import YarnCommandError
 from cachi2.core.rooted_path import RootedPath
 from cachi2.core.utils import run_cmd
 
@@ -9,7 +12,9 @@ def run_yarn_cmd(cmd: list[str], source_dir: RootedPath, env: dict[str, str]) ->
     :param source_dir: the directory in the repository containing the yarn source files.
     :param env: environment variables to be set during the command's execution.
 
-    :raises SubprocessCallError: if the command fails.
+    :raises YarnCommandError: if the command fails.
     """
-    run_cmd(cmd=["yarn", *cmd], params={"cwd": source_dir, "env": env})
-    return NotImplemented
+    try:
+        return run_cmd(cmd=["yarn", *cmd], params={"cwd": source_dir, "env": env})
+    except subprocess.CalledProcessError:
+        raise YarnCommandError(f"Yarn command failed: {' '.join(cmd)}")

cachi2/core/utils.py

@@ -17,7 +17,7 @@ def run_cmd(cmd: Any, params: dict) -> str:
     :param dict params: keyword parameters for command execution
     :returns: the command output
     :rtype: str
-    :raises SubprocessCallError: if the command fails
+    :raises CalledProcessError: if the command fails
     """
     params.setdefault("capture_output", True)
     params.setdefault("universal_newlines", True)

tests/unit/package_managers/yarn/test_main.py

@@ -0,0 +1,26 @@
+from unittest import mock
+
+import pytest
+
+from cachi2.core.errors import YarnCommandError
+from cachi2.core.package_managers.yarn.main import _fetch_dependencies
+from cachi2.core.rooted_path import RootedPath
+
+
+@mock.patch("cachi2.core.package_managers.yarn.main.run_yarn_cmd")
+def test_fetch_dependencies(mock_yarn_cmd: mock.Mock, rooted_tmp_path: RootedPath) -> None:
+    source_dir = rooted_tmp_path
+    output_dir = rooted_tmp_path.join_within_root("cachi2-output")
+
+    mock_yarn_cmd.side_effect = YarnCommandError("berryscary")
+
+    with pytest.raises(YarnCommandError) as exc_info:
+        _fetch_dependencies(source_dir, output_dir)
+
+    mock_yarn_cmd.assert_called_once_with(
+        ["install", "--mode", "skip-build"],
+        source_dir,
+        {"YARN_GLOBAL_FOLDER": str(output_dir.join_within_root("deps", "yarn"))},
+    )
+
+    assert str(exc_info.value) == "berryscary"

tests/unit/test_errors.py

@@ -54,6 +54,21 @@ def test_gomod_error_friendly_msg() -> None:
     assert err.friendly_msg() == expect_msg
 
 
+def test_yarn_command_error_friendly_msg() -> None:
+    err = errors.YarnCommandError("Some yarn command failed")
+    expect_msg = dedent(
+        """
+        Some yarn command failed
+          The cause of the failure could be:
+          - something is broken in Cachi2
+          - something is wrong with your yarn project
+          - communication with an external service failed (please try again)
+          The output of the failing yarn command should provide more details, please check the logs.
+        """
+    ).strip()
+    assert err.friendly_msg() == expect_msg
+
+
 def test_fetch_error_friendly_msg() -> None:
     err = errors.FetchError("Failed to fetch something")
     expect_msg = dedent(