Provide res-marg CLI via .cli and associated tools

- Integrate with existing `mix-models` CLI.
- Remove duplicated code for model/scenario/version arguments, loading
  platform and scenario, etc.
- Simplify tests.

Author: khaeru

message_ix_models/cli.py

@@ -168,6 +168,7 @@ def _log_threads(k: int, n: int):
     "message_ix_models.report.cli",
     "message_ix_models.model.material.cli",
     "message_ix_models.testing.cli",
+    "message_ix_models.tools.res_marg",
     "message_ix_models.util.pooch",
     "message_ix_models.util.slurm",
 ]

message_ix_models/tests/tools/test_res_marg.py

@@ -1,24 +1,20 @@
-from subprocess import CalledProcessError, check_call
-
 import pytest
 
 from message_ix_models.tools.res_marg import main
 
 
-def test_cli() -> None:
+def test_cli(mix_models_cli) -> None:
     """Run :func:`.res_marg.main` via its command-line interface."""
     command = [
-        "python",
-        "-m",
-        "message_ix_models.tools.res_marg",
+        "--model=model_name",
+        "--scenario=scenario_name",
         "--version=123",
-        "model_name",
-        "scenario_name",
+        "res-marg",
     ]
 
-    # Fails: the model name, scenario name, and version do not exit
-    with pytest.raises(CalledProcessError):
-        check_call(command)
+    # Fails: the model name, scenario name, and version do not exist
+    with pytest.raises(RuntimeError):
+        mix_models_cli.assert_exit_0(command)
 
 
 @pytest.mark.xfail(reason="Function does not run on the snapshot")

message_ix_models/tools/res_marg.py

@@ -1,11 +1,18 @@
-"""Update the reserve margin."""
+"""Update the reserve margin.
+
+:func:`main` can also be invoked using the CLI command
+:program:`mix-models --url=… res-marg`.
+"""
 
-import argparse
 from typing import TYPE_CHECKING
 
+import click
+
 if TYPE_CHECKING:
     from message_ix import Scenario
 
+    from message_ix_models import Context
+
 
 def main(scen: "Scenario", contin: float = 0.2) -> None:
     """Update the reserve margin.
@@ -100,34 +107,8 @@ def main(scen: "Scenario", contin: float = 0.2) -> None:
                 )
 
 
-if __name__ == "__main__":
-    descr = """
-    Reserve margin calculation
-
-    Example usage:
-    python res_marg.py --version [X] [model name] [scenario name]
-
-    """
-    parser = argparse.ArgumentParser(
-        description=descr, formatter_class=argparse.RawDescriptionHelpFormatter
-    )
-    version = "--version : string\n    ix-scenario name"
-    parser.add_argument("--version", help=version)
-    model = "model : string\n    ix-model name"
-    parser.add_argument("model", help=model)
-    scenario = "scenario : string\n    ix-scenario name"
-    parser.add_argument("scenario", help=scenario)
-
-    # parse cli
-    args = parser.parse_args()
-    model = args.model
-    scenario = args.scenario
-    version = int(args.version) if args.version else None
-
-    import ixmp
-    import message_ix
-
-    mp = ixmp.Platform()
-    scen = message_ix.Scenario(mp, model, scenario, version=version, cache=True)
-
-    main(scen)
+@click.command("res-marg")
+@click.pass_obj
+def cli(ctx: "Context"):
+    """Reserve margin calculation."""
+    main(ctx.get_scenario())