fix: fix broken dynamic import of rplugin modules

pynvim/plugin/host.py

@@ -1,10 +1,13 @@
 # type: ignore
 """Implements a Nvim host for python plugins."""
+
+import importlib
 import inspect
 import logging
 import os
 import os.path
 import re
+import sys
 from functools import partial
 from traceback import format_exc
 from typing import Any, Sequence
@@ -23,25 +26,18 @@
 host_method_spec = {"poll": {}, "specs": {"nargs": 1}, "shutdown": {}}
 
 
-def handle_import(directory, name):
-    """Import a python file given a known location.
+def _handle_import(path: str, name: str):
+    """Import python module `name` from a known file path or module directory.
 
-    Currently works on both python2 or 3.
+    The path should be the base directory from which the module can be imported.
+    To support python 3.12, the use of `imp` should be avoided.
+    @see https://docs.python.org/3.12/whatsnew/3.12.html#imp
     """
-    try:  # Python3
-        from importlib.util import module_from_spec, spec_from_file_location
-    except ImportError:  # Python2.7
-        import imp
-        from pynvim.compat import find_module
-        file, pathname, descr = find_module(name, [directory])
-        module = imp.load_module(name, file, pathname, descr)
-        return module
-    else:
-        spec = spec_from_file_location(name, location=directory)
-        if spec is not None:
-            return module_from_spec(spec)
-        else:
-            raise ImportError
+    if not name:
+        raise ValueError("Missing module name.")
+
+    sys.path.append(path)
+    return importlib.import_module(name)
 
 
 class Host(object):
@@ -167,22 +163,28 @@ def _missing_handler_error(self, name, kind):
         return msg
 
     def _load(self, plugins: Sequence[str]) -> None:
+        """Load the remote plugins and register handlers defined in the plugins.
+
+        Args:
+            plugins: List of plugin paths to rplugin python modules
+                registered by remote#host#RegisterPlugin('python3', ...)
+                (see the generated rplugin.vim manifest)
+        """
+        # self.nvim.err_write("host init _load\n", async_=True)
         has_script = False
         for path in plugins:
+            path = os.path.normpath(path)  # normalize path
             err = None
             if path in self._loaded:
-                error('{} is already loaded'.format(path))
+                warn('{} is already loaded'.format(path))
                 continue
             try:
                 if path == "script_host.py":
                     module = script_host
                     has_script = True
                 else:
                     directory, name = os.path.split(os.path.splitext(path)[0])
-                    try:
-                        module = handle_import(directory, name)
-                    except ImportError:
-                        return
+                    module = _handle_import(directory, name)
                 handlers = []
                 self._discover_classes(module, handlers, path)
                 self._discover_functions(module, handlers, path, False)

test/fixtures/module_plugin/rplugin/python3/mymodule/__init__.py

@@ -0,0 +1,9 @@
+"""The `mymodule` package for the fixture module plugin."""
+# pylint: disable=all
+
+# Somehow the plugin might be using relative imports.
+from .plugin import MyPlugin as MyPlugin
+
+# ... or absolute import (assuming this is the root package)
+import mymodule.plugin  # noqa: I100
+assert mymodule.plugin.MyPlugin is MyPlugin

test/fixtures/module_plugin/rplugin/python3/mymodule/plugin.py

@@ -0,0 +1,13 @@
+"""Actual implement lies here."""
+import pynvim as neovim
+import pynvim.api
+
+
+@neovim.plugin
+class MyPlugin:
+    def __init__(self, nvim: pynvim.api.Nvim):
+        self.nvim = nvim
+
+    @neovim.command("ModuleHelloWorld")
+    def hello_world(self) -> None:
+        self.nvim.command("echom 'MyPlugin: Hello World!'")

test/fixtures/simple_plugin/rplugin/python3/simple_nvim.py

@@ -0,0 +1,13 @@
+import neovim
+
+import pynvim.api
+
+
+@neovim.plugin
+class SimplePlugin:
+    def __init__(self, nvim: pynvim.api.Nvim):
+        self.nvim = nvim
+
+    @neovim.command("SimpleHelloWorld")
+    def hello_world(self) -> None:
+        self.nvim.command("echom 'SimplePlugin: Hello World!'")

test/test_host.py

@@ -1,8 +1,13 @@
-# -*- coding: utf-8 -*-
 # type: ignore
+# pylint: disable=protected-access
+import os
+from typing import Sequence
+
 from pynvim.plugin.host import Host, host_method_spec
 from pynvim.plugin.script_host import ScriptHost
 
+__PATH__ = os.path.abspath(os.path.dirname(__file__))
+
 
 def test_host_imports(vim):
     h = ScriptHost(vim)
@@ -11,6 +16,24 @@ def test_host_imports(vim):
     assert h.module.__dict__['sys']
 
 
+def test_host_import_rplugin_modules(vim):
+    # Test whether a Host can load and import rplugins (#461).
+    # See also $VIMRUNTIME/autoload/provider/pythonx.vim.
+    h = Host(vim)
+    plugins: Sequence[str] = [  # plugin paths like real rplugins
+        os.path.join(__PATH__, "./fixtures/simple_plugin/rplugin/python3/simple_nvim.py"),
+        os.path.join(__PATH__, "./fixtures/module_plugin/rplugin/python3/mymodule/"),
+        os.path.join(__PATH__, "./fixtures/module_plugin/rplugin/python3/mymodule"),  # duplicate
+    ]
+    h._load(plugins)
+    assert len(h._loaded) == 2
+
+    # pylint: disable-next=unbalanced-tuple-unpacking
+    simple_nvim, mymodule = list(h._loaded.values())
+    assert simple_nvim['module'].__name__ == 'simple_nvim'
+    assert mymodule['module'].__name__ == 'mymodule'
+
+
 def test_host_clientinfo(vim):
     h = Host(vim)
     assert h._request_handlers.keys() == host_method_spec.keys()