Register installed CLI plugins at program start (#896)

register_cli_plugins() ran while mvt.ios and mvt.android were being
imported, so importing any part of MVT executed the entry points of every
installed command package. That made plugin loading depend on import
order: a plugin importing from MVT while MVT was still initializing got an
ImportError and was quietly demoted to a broken command, and the same
plugin worked when MVT happened to be imported first.

Move the call into a main() function in each CLI module and point the
console scripts at it, so registration happens once when the program
starts and importing MVT no longer runs third-party code. For packagers:
mvt.ios:cli and mvt.android:cli stay importable, but a wrapper invoking
cli() directly no longer registers the installed plugin commands and
should call main() instead.

tests/test_cli_entry_points.py

@@ -0,0 +1,215 @@
+# Mobile Verification Toolkit (MVT)
+# Copyright (c) 2021-2026 The MVT Authors.
+# Use of this software is governed by the MVT License 1.1 that can be found at
+#   https://license.mvt.re/1.1/
+
+import sys
+from types import SimpleNamespace
+
+import click
+import pytest
+
+import mvt.android
+import mvt.ios
+from mvt.android.cli import cli as android_cli
+from mvt.android.cli import main as android_main
+from mvt.common.cli_plugins import ANDROID_CLI_PLUGIN_GROUP, IOS_CLI_PLUGIN_GROUP
+from mvt.ios.cli import cli as ios_cli
+from mvt.ios.cli import main as ios_main
+
+from .plugin_fixtures import (
+    FIXTURE_COMMAND_NAME,
+    run_isolated_python,
+    write_cli_plugin_distribution,
+)
+
+MARKER_PLUGIN_TEMPLATE = """
+import os
+
+import click
+
+# Touched when this module is imported, so a test can tell whether loading MVT
+# executed the plugin.
+open(os.environ["FIXTURE_PLUGIN_MARKER"], "a").close()
+
+
+@click.command()
+def cli():
+    click.echo("fixture plugin ran")
+"""
+
+PROGRAMS = {
+    "mvt-ios": (mvt.ios, ios_cli, IOS_CLI_PLUGIN_GROUP),
+    "mvt-android": (mvt.android, android_cli, ANDROID_CLI_PLUGIN_GROUP),
+}
+
+
+@pytest.fixture
+def restore_cli_commands():
+    """Undo the plugin registration main() performs on the shared CLI groups."""
+    originals = {
+        program: dict(group.commands) for program, (_, group, _) in PROGRAMS.items()
+    }
+    yield
+    for program, (_, group, _) in PROGRAMS.items():
+        group.commands.clear()
+        group.commands.update(originals[program])
+        if hasattr(group, "_mvt_external_command_sources"):
+            delattr(group, "_mvt_external_command_sources")
+
+
+def _install_fixture_entry_point(monkeypatch, entry_point_group, command):
+    def entry_points(*, group):
+        if group != entry_point_group:
+            return []
+        return [
+            SimpleNamespace(
+                name=FIXTURE_COMMAND_NAME,
+                value="fixture_cli_plugin:cli",
+                load=lambda: command,
+                dist=SimpleNamespace(
+                    metadata={"Name": "fixture-cli-plugin"}, version="1.0"
+                ),
+            )
+        ]
+
+    monkeypatch.setattr(
+        "mvt.common.cli_plugins.importlib.metadata.entry_points", entry_points
+    )
+
+
+def _offline_argv(program, *arguments):
+    """Build an argument list which keeps the CLI from checking for updates."""
+    return [
+        program,
+        "--disable-update-check",
+        "--disable-indicator-update-check",
+        *arguments,
+    ]
+
+
+@pytest.mark.parametrize("program", sorted(PROGRAMS))
+def test_main_registers_installed_plugins_before_running_the_cli(
+    program, monkeypatch, capsys, restore_cli_commands
+):
+    package, group, entry_point_group = PROGRAMS[program]
+
+    @click.command()
+    def fixture_command():
+        click.echo("fixture plugin ran")
+
+    _install_fixture_entry_point(monkeypatch, entry_point_group, fixture_command)
+    monkeypatch.setattr(sys, "argv", _offline_argv(program, FIXTURE_COMMAND_NAME))
+
+    with pytest.raises(SystemExit) as exit_info:
+        package.main()
+
+    assert exit_info.value.code == 0
+    assert "fixture plugin ran" in capsys.readouterr().out
+    assert FIXTURE_COMMAND_NAME in group.commands
+
+
+@pytest.mark.parametrize("program", sorted(PROGRAMS))
+def test_main_completes_plugin_command_names(
+    program, monkeypatch, capsys, restore_cli_commands
+):
+    package, _, entry_point_group = PROGRAMS[program]
+
+    @click.command()
+    def fixture_command():
+        pass
+
+    _install_fixture_entry_point(monkeypatch, entry_point_group, fixture_command)
+    complete_variable = f"_{program.upper().replace('-', '_')}_COMPLETE"
+    monkeypatch.setenv(complete_variable, "bash_complete")
+    monkeypatch.setenv("COMP_WORDS", f"{program} fixture")
+    monkeypatch.setenv("COMP_CWORD", "1")
+    monkeypatch.setattr(sys, "argv", [program])
+
+    with pytest.raises(SystemExit):
+        package.main()
+
+    assert f"plain,{FIXTURE_COMMAND_NAME}" in capsys.readouterr().out
+
+
+@pytest.mark.parametrize("program", sorted(PROGRAMS))
+def test_main_still_loads_commands_from_a_file(
+    program, monkeypatch, capsys, tmp_path, restore_cli_commands
+):
+    package, _, entry_point_group = PROGRAMS[program]
+    command_path = tmp_path / "case_summary.py"
+    command_path.write_text(
+        "import click\n"
+        "\n"
+        "\n"
+        '@click.command("case-summary")\n'
+        "def cli():\n"
+        '    click.echo("case summary ran")\n',
+        encoding="utf-8",
+    )
+    _install_fixture_entry_point(
+        monkeypatch, entry_point_group, click.Command("unused")
+    )
+    monkeypatch.setattr(
+        sys,
+        "argv",
+        _offline_argv(program, "--load-command", str(command_path), "case-summary"),
+    )
+
+    with pytest.raises(SystemExit) as exit_info:
+        package.main()
+
+    assert exit_info.value.code == 0
+    assert "case summary ran" in capsys.readouterr().out
+
+
+def test_the_console_script_targets_are_importable():
+    # [project.scripts] points at these, so they must stay on the packages.
+    assert mvt.ios.main is ios_main
+    assert mvt.android.main is android_main
+
+
+def test_importing_mvt_does_not_run_installed_plugins(tmp_path):
+    site_path = write_cli_plugin_distribution(
+        tmp_path / "site", IOS_CLI_PLUGIN_GROUP, MARKER_PLUGIN_TEMPLATE
+    )
+    marker = tmp_path / "plugin-imported"
+
+    result = run_isolated_python(
+        "import mvt.ios.cli\nimport mvt.android.cli\nprint('imported')",
+        home=tmp_path / "home",
+        site_path=site_path,
+        FIXTURE_PLUGIN_MARKER=str(marker),
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert "imported" in result.stdout
+    assert not marker.exists()
+
+
+def test_registering_the_plugins_runs_the_entry_point(tmp_path):
+    site_path = write_cli_plugin_distribution(
+        tmp_path / "site", IOS_CLI_PLUGIN_GROUP, MARKER_PLUGIN_TEMPLATE
+    )
+    marker = tmp_path / "plugin-imported"
+
+    result = run_isolated_python(
+        "import click\n"
+        "from mvt.common.cli_plugins import (\n"
+        "    IOS_CLI_PLUGIN_GROUP,\n"
+        "    BrokenPluginCommand,\n"
+        "    register_installed_cli_commands,\n"
+        ")\n"
+        "group = click.Group()\n"
+        "register_installed_cli_commands(group, IOS_CLI_PLUGIN_GROUP)\n"
+        f"command = group.commands[{FIXTURE_COMMAND_NAME!r}]\n"
+        "assert not isinstance(command, BrokenPluginCommand), command.help\n"
+        "print('registered')\n",
+        home=tmp_path / "home",
+        site_path=site_path,
+        FIXTURE_PLUGIN_MARKER=str(marker),
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert "registered" in result.stdout
+    assert marker.exists()