Add tmt about, command showing things about tmt itself

tmt/__main__.py

@@ -6,6 +6,7 @@ def import_cli_commands() -> None:
 
     # TODO: some kind of `import tmt.cli.*` would be nice
     import tmt.cli._root  # type: ignore[reportUnusedImport,unused-ignore]
+    import tmt.cli.about  # noqa: F401,I001,RUF100
     import tmt.cli.init  # noqa: F401,I001,RUF100
     import tmt.cli.lint  # noqa: F401,I001,RUF100
     import tmt.cli.status  # noqa: F401,I001,RUF100

tmt/checks/__init__.py

@@ -26,7 +26,7 @@
 
 CheckPluginClass = type['CheckPlugin[Any]']
 
-_CHECK_PLUGIN_REGISTRY: PluginRegistry[CheckPluginClass] = PluginRegistry()
+_CHECK_PLUGIN_REGISTRY: PluginRegistry[CheckPluginClass] = PluginRegistry('test.check')
 
 
 def provides_check(check: str) -> Callable[[CheckPluginClass], CheckPluginClass]:

tmt/cli/about.py

@@ -0,0 +1,89 @@
+""" ``tmt about`` implementation """
+
+import json
+import re
+import textwrap
+from typing import Any
+
+import tmt.utils
+import tmt.utils.rest
+from tmt.cli import Context, CustomGroup, pass_context
+from tmt.cli._root import main
+from tmt.options import option
+from tmt.plugins import PluginRegistry, iter_plugin_registries
+from tmt.utils import GeneralError
+from tmt.utils.templates import render_template
+
+
+@main.group(invoke_without_command=True, cls=CustomGroup)
+def about() -> None:
+    """ Show info about tmt itself """
+
+
+def _render_plugins_rest() -> str:
+    registry_intro_map: dict[str, str] = {
+        r'export\.([a-z]+)': 'Export plugins for {{ MATCH.group(1).lower() }}',
+        r'test.check': 'Test check plugins',
+        r'test.framework': 'Test framework plugins',
+        r'package_manager': 'Package manager plugins',
+        r'step\.([a-z]+)': '{{ MATCH.group(1).capitalize() }} step plugins'
+        }
+
+    def find_intro(registry: PluginRegistry[Any]) -> str:
+        for pattern, intro_template in registry_intro_map.items():
+            match = re.match(pattern, registry.name)
+
+            if match is None:
+                continue
+
+            return render_template(intro_template, MATCH=match)
+
+        raise GeneralError(f"Unknown plugin registry '{registry.name}'.")
+
+    template = textwrap.dedent("""
+        {% for registry in REGISTRIES %}
+            {% set intro = find_intro(registry) %}
+        {{ intro }}
+        {# {{ "-" * intro | length }} #}
+
+            {% if registry %}
+                {% for plugin_id in registry.iter_plugin_ids() %}
+        * `{{ plugin_id }}`
+                {% endfor %}
+            {% else %}
+        No plugins discovered.
+            {% endif %}
+
+        ----
+
+        {% endfor %}
+    """)
+
+    return render_template(template, REGISTRIES=iter_plugin_registries(), find_intro=find_intro)
+
+
+@about.command()
+@option(
+    '-h', '--how',
+    choices=['json', 'yaml', 'rest', 'pretty'],
+    default='pretty',
+    help='Output format.')
+@pass_context
+def plugins(context: Context, how: str) -> None:
+    print = context.obj.logger.print  # noqa: A001
+
+    if how in ('pretty', 'rest'):
+        text_output = _render_plugins_rest()
+
+        print(
+            tmt.utils.rest.render_rst(text_output, context.obj.logger)
+            if how == 'pretty' else text_output)
+
+    elif how in ('json', 'yaml'):
+        structured_output = {
+            registry.name: list(registry.iter_plugin_ids())
+            for registry in iter_plugin_registries()
+            }
+
+        print(json.dumps(structured_output) if how ==
+              'json' else tmt.utils.dict_to_yaml(structured_output))

tmt/export/__init__.py

@@ -86,7 +86,7 @@ def get_export_plugin_registry(cls) -> PluginRegistry[ExportClass]:
         """ Return - or initialize - export plugin registry """
 
         if not hasattr(cls, '_export_plugin_registry'):
-            cls._export_plugin_registry = PluginRegistry()
+            cls._export_plugin_registry = PluginRegistry(f'export.{cls.__name__.lower()}')
 
         return cls._export_plugin_registry
 

tmt/frameworks/__init__.py

@@ -14,7 +14,7 @@
 
 
 _FRAMEWORK_PLUGIN_REGISTRY: tmt.plugins.PluginRegistry[TestFrameworkClass] = \
-    tmt.plugins.PluginRegistry()
+    tmt.plugins.PluginRegistry('test.framework')
 
 
 def provides_framework(framework: str) -> Callable[[TestFrameworkClass], TestFrameworkClass]:

tmt/package_managers/__init__.py

@@ -68,7 +68,7 @@ def __lt__(self, other: Any) -> bool:
 
 
 _PACKAGE_MANAGER_PLUGIN_REGISTRY: tmt.plugins.PluginRegistry[PackageManagerClass] = \
-    tmt.plugins.PluginRegistry()
+    tmt.plugins.PluginRegistry('package_managers')
 
 
 def provides_package_manager(

tmt/plugins/__init__.py

@@ -307,7 +307,9 @@ class PluginRegistry(Generic[RegisterableT]):
 
     _plugins: dict[str, RegisterableT]
 
-    def __init__(self) -> None:
+    def __init__(self, name: str) -> None:
+        self.name = name
+
         self._plugins = {}
 
     def register_plugin(
@@ -370,6 +372,12 @@ def iter_plugins(self) -> Iterator[RegisterableT]:
     def items(self) -> Iterator[tuple[str, RegisterableT]]:
         yield from self._plugins.items()
 
+    def __len__(self) -> int:
+        return len(self._plugins)
+
+    def __bool__(self) -> bool:
+        return bool(self._plugins)
+
 
 class ModuleImporter(Generic[ModuleT]):
     """
@@ -402,3 +410,38 @@ def __call__(self, logger: Logger) -> ModuleT:
 
         assert self._module  # narrow type
         return self._module
+
+
+def iter_plugin_registries() -> Iterator[PluginRegistry[Any]]:
+    # TODO: maybe there is a better way, but as of now, registries do
+    # not report their existence, there is no method to iterate over
+    # them. Using a static list for now.
+    from tmt.base import Plan, Story, Test
+    from tmt.checks import _CHECK_PLUGIN_REGISTRY
+    from tmt.frameworks import _FRAMEWORK_PLUGIN_REGISTRY
+    from tmt.package_managers import _PACKAGE_MANAGER_PLUGIN_REGISTRY
+    from tmt.steps.discover import DiscoverPlugin
+    from tmt.steps.execute import ExecutePlugin
+    from tmt.steps.finish import FinishPlugin
+    from tmt.steps.prepare import PreparePlugin
+    from tmt.steps.provision import ProvisionPlugin
+    from tmt.steps.report import ReportPlugin
+
+    yield Story._export_plugin_registry
+    yield Plan._export_plugin_registry
+    yield Test._export_plugin_registry
+    yield _CHECK_PLUGIN_REGISTRY
+    yield _FRAMEWORK_PLUGIN_REGISTRY
+    yield _PACKAGE_MANAGER_PLUGIN_REGISTRY
+    yield DiscoverPlugin._supported_methods
+    yield ProvisionPlugin._supported_methods
+    yield PreparePlugin._supported_methods
+    yield ExecutePlugin._supported_methods
+    yield FinishPlugin._supported_methods
+    yield ReportPlugin._supported_methods
+
+
+def iter_plugins() -> Iterator[tuple[PluginRegistry[RegisterableT], str, RegisterableT]]:
+    for registry in iter_plugin_registries():
+        for plugin_id, plugin_class in registry.items():
+            yield registry, plugin_id, plugin_class

tmt/steps/discover/__init__.py

@@ -83,7 +83,7 @@ class DiscoverPlugin(tmt.steps.GuestlessPlugin[DiscoverStepDataT, None]):
     _data_class = DiscoverStepData  # type: ignore[assignment]
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry('step.discover')
 
     @classmethod
     def base_command(

tmt/steps/execute/__init__.py

@@ -609,7 +609,7 @@ class ExecutePlugin(tmt.steps.Plugin[ExecuteStepDataT, None]):
     _data_class = ExecuteStepData  # type: ignore[assignment]
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry('step.execute')
 
     # Internal executor is the default implementation
     how = 'tmt'

tmt/steps/finish/__init__.py

@@ -41,7 +41,7 @@ class FinishPlugin(tmt.steps.Plugin[FinishStepDataT, list[PhaseResult]]):
     _data_class = FinishStepData  # type: ignore[assignment]
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[Method] = PluginRegistry('step.finish')
 
     @classmethod
     def base_command(

tmt/steps/prepare/__init__.py

@@ -53,7 +53,7 @@ class PreparePlugin(tmt.steps.Plugin[PrepareStepDataT, list[PhaseResult]]):
     _data_class = PrepareStepData  # type: ignore[assignment]
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry('step.prepare')
 
     @classmethod
     def base_command(

tmt/steps/prepare/feature/__init__.py

@@ -18,7 +18,7 @@
 FEATURE_PLAYEBOOK_DIRECTORY = tmt.utils.resource_files('steps/prepare/feature')
 
 FeatureClass = type['Feature']
-_FEATURE_PLUGIN_REGISTRY: PluginRegistry[FeatureClass] = PluginRegistry()
+_FEATURE_PLUGIN_REGISTRY: PluginRegistry[FeatureClass] = PluginRegistry('prepare.feature')
 
 
 def provides_feature(

tmt/steps/provision/__init__.py

@@ -2285,7 +2285,7 @@ class ProvisionPlugin(tmt.steps.GuestlessPlugin[ProvisionStepDataT, None]):
     how = 'virtual'
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry('step.provision')
 
     # TODO: Generics would provide a better type, https://github.com/teemtee/tmt/issues/1437
     _guest: Optional[Guest] = None

tmt/steps/report/__init__.py

@@ -33,7 +33,7 @@ class ReportPlugin(tmt.steps.GuestlessPlugin[ReportStepDataT, None]):
     how = 'display'
 
     # Methods ("how: ..." implementations) registered for the same step.
-    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry()
+    _supported_methods: PluginRegistry[tmt.steps.Method] = PluginRegistry('step.report')
 
     @classmethod
     def base_command(