cli: Sort loaders list and fix some tests

New tests are failing since the number of available loaders increased.
Associated loaders list gets now wrapped in cli help output so we need
to take this into account in tests implementation.

swh/loader/cli.py

@@ -25,7 +25,7 @@ LOADERS = {
 }
 
 
-SUPPORTED_LOADERS = list(LOADERS)
+SUPPORTED_LOADERS = sorted(list(LOADERS))
 
 
 def get_loader(name: str, **kwargs) -> Any:

swh/loader/tests/test_cli.py

@@ -9,6 +9,7 @@ import pytest
 from swh.loader.cli import run, list, get_loader, SUPPORTED_LOADERS
 from swh.loader.package.loader import PackageLoader
 
+from click.formatting import HelpFormatter
 from click.testing import CliRunner
 
 
@@ -38,6 +39,12 @@ def test_get_loader(swh_config):
         assert isinstance(loader, PackageLoader)
 
 
+def _write_usage(command, args, max_width=80):
+    hf = HelpFormatter(width=max_width)
+    hf.write_usage(command, args)
+    return hf.getvalue()[:-1]
+
+
 def test_run_help(swh_config):
     """Help message should be ok
 
@@ -46,15 +53,16 @@ def test_run_help(swh_config):
     result = runner.invoke(run, ["-h"])
 
     assert result.exit_code == 0
-    expected_help_msg = """Usage: run [OPTIONS] [archive|cran|debian|deposit|nixguix|npm|pypi] URL
-           [OPTIONS]...
+    usage_prefix = _write_usage(
+        "run", f"[OPTIONS] [{'|'.join(SUPPORTED_LOADERS)}] URL [OPTIONS]..."
+    )
+    expected_help_msg = f"""{usage_prefix}
 
   Ingest with loader <type> the origin located at <url>
 
 Options:
   -h, --help  Show this message and exit.
-"""  # noqa
-
+"""
     assert result.output.startswith(expected_help_msg)
 
 
@@ -76,13 +84,16 @@ def test_list_help(mocker, swh_config):
     runner = CliRunner()
     result = runner.invoke(list, ["--help"])
     assert result.exit_code == 0
-    expected_help_msg = """Usage: list [OPTIONS] [[all|archive|cran|debian|deposit|nixguix|npm|pypi]]
+    usage_prefix = _write_usage(
+        "list", f"[OPTIONS] [[{'|'.join(['all'] + SUPPORTED_LOADERS)}]]"
+    )
+    expected_help_msg = f"""{usage_prefix}
 
   List supported loaders and optionally their arguments
 
 Options:
   -h, --help  Show this message and exit.
-"""  # noqa
+"""
     assert result.output.startswith(expected_help_msg)
 
 
@@ -93,7 +104,8 @@ def test_list_help_npm(mocker, swh_config):
     runner = CliRunner()
     result = runner.invoke(list, ["npm"])
     assert result.exit_code == 0
-    expected_help_msg = """Loader: Load npm origin's artifact releases into swh archive.
+    expected_help_msg = """
+Loader: Load npm origin's artifact releases into swh archive.
 signature: (url: str)
-"""  # noqa
-    assert result.output.startswith(expected_help_msg)
+"""
+    assert result.output.startswith(expected_help_msg[1:])