test(plugin-cli): expand BDD tests to cover all happy paths and long-description truncation

Add mock-based @given steps and 14 new scenarios covering the rich
table list, show, enable, disable, remove happy paths, the abort
confirmation flow, and the description truncation branch
(plugin.py:134). The @when step now patches _get_plugin_manager via
context so PluginManager isolation works without a singleton.

ISSUES CLOSED: #5756

features/steps/plugin_cli_steps.py

@@ -4,8 +4,56 @@ from __future__ import annotations
 
 import json
 from typing import Any
+from unittest.mock import MagicMock, patch
 
-from behave import then, when
+from behave import given, then, when
+
+from cleveragents.infrastructure.plugins.types import PluginState
+
+
+def _make_plugin_manager(
+    state: PluginState, description: str = "A test plugin"
+) -> MagicMock:
+    """Create a mock PluginManager with one test plugin in the given state."""
+    descriptor = MagicMock()
+    descriptor.name = "test-plugin"
+    descriptor.version = "1.0.0"
+    descriptor.description = description
+    descriptor.module_path = "test.module"
+    descriptor.class_name = "TestPlugin"
+    descriptor.state = state
+
+    manager = MagicMock()
+    manager.list_plugins.return_value = [descriptor]
+    manager.get_plugin.return_value = descriptor
+    return manager
+
+
+@given("a plugin manager with one active plugin")
+def step_plugin_manager_active(context: Any) -> None:
+    """Set up a mock PluginManager with one ACTIVATED plugin."""
+    context.plugin_manager = _make_plugin_manager(PluginState.ACTIVATED)
+
+
+@given("a plugin manager with one inactive plugin")
+def step_plugin_manager_inactive(context: Any) -> None:
+    """Set up a mock PluginManager with one DEACTIVATED plugin."""
+    context.plugin_manager = _make_plugin_manager(PluginState.DEACTIVATED)
+
+
+@given("a plugin manager with one plugin having a long description")
+def step_plugin_manager_long_desc(context: Any) -> None:
+    """Set up a mock PluginManager with a plugin whose description exceeds 40 chars."""
+    context.plugin_manager = _make_plugin_manager(
+        PluginState.ACTIVATED,
+        description="A" * 50,
+    )
+
+
+@given('the next prompt answer is "{answer}"')
+def step_set_prompt_answer(context: Any, answer: str) -> None:
+    """Store stdin input to be used by the next plugin CLI invocation."""
+    context.cli_input = answer + "\n"
 
 
 @when('I run "agents plugin {args}"')
@@ -15,7 +63,24 @@ def step_run_agents_plugin(context: Any, args: str) -> None:
 
     from cleveragents.cli.main import app
 
-    result = CliRunner().invoke(app, ["plugin", *args.split()], catch_exceptions=True)
+    plugin_manager = getattr(context, "plugin_manager", None)
+    stdin = getattr(context, "cli_input", None)
+    runner = CliRunner()
+    split_args = args.split()
+
+    if plugin_manager is not None:
+        with patch(
+            "cleveragents.cli.commands.plugin._get_plugin_manager",
+            return_value=plugin_manager,
+        ):
+            result = runner.invoke(
+                app, ["plugin", *split_args], input=stdin, catch_exceptions=True
+            )
+    else:
+        result = runner.invoke(
+            app, ["plugin", *split_args], input=stdin, catch_exceptions=True
+        )
+
     context.command_output = result.output or ""