Add default mypy config file reference

pylsp_mypy/plugin.py

@@ -278,8 +278,10 @@ def init(workspace: str) -> Dict[str, str]:
 
     mypyConfigFile = findConfigFile(workspace, ["mypy.ini", ".mypy.ini"])
     mypyConfigFileMap[workspace] = mypyConfigFile
+    if mypyConfigFileMap[workspace] is None:
+        mypyConfigFileMap[workspace] = defaultMypyConfigFile()
 
-    log.info("mypyConfigFile = %s configuration = %s", mypyConfigFile, configuration)
+    log.info("mypyConfigFile = %s configuration = %s", mypyConfigFileMap[workspace], configuration)
     return configuration
 
 
@@ -320,6 +322,30 @@ def findConfigFile(path: str, names: List[str]) -> Optional[str]:
     return None
 
 
+def defaultMypyConfigFile() -> Optional[str]:
+    """
+    Find the mypy default config file path defined in the mypy document below.
+
+    Reference: https://mypy.readthedocs.io/en/stable/config_file.html
+
+    Returns
+    -------
+    Optional[str]
+        The path where the default config file has been found or None if no matching file has been found.
+
+    """
+    # A list of user default config file path
+    user_default_config = ["~/.config/mypy/config", "~/.mypy.ini"]
+    if os.environ.get("XDG_CONFIG_HOME"):
+        user_default_config.insert(0, os.path.join(os.environ["XDG_CONFIG_HOME"], "mypy/config"))
+
+    for config_file in user_default_config:
+        if Path(config_file).expanduser().exists():
+            return config_file
+
+    return None
+
+
 @atexit.register
 def close() -> None:
     """

test/test_plugin.py

@@ -3,7 +3,7 @@
 from pylsp.workspace import Workspace, Document
 from pylsp.config.config import Config
 from pylsp import uris
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 from pylsp_mypy import plugin
 
 DOC_URI = __file__
@@ -20,6 +20,7 @@
 def workspace(tmpdir):
     """Return a workspace."""
     ws = Workspace(uris.from_fs_path(str(tmpdir)), Mock())
+    ws._root_path = "C:"
     ws._config = Config(ws.root_uri, {}, 0, {})
     return ws
 
@@ -120,3 +121,12 @@ def foo():
     doc2 = Document(DOC_URI, ws2, DOC_SOURCE)
     diags = plugin.pylsp_lint(ws2._config, ws2, doc2, is_saved=False)
     assert len(diags) == 0
+
+
+def test_default_config_file(tmpdir):
+    config = FakeConfig()
+    with patch("pylsp_mypy.plugin.findConfigFile", return_value=None), patch(
+        "pathlib.Path.exists", return_value=True
+    ):
+        plugin.pylsp_settings(config)
+        assert plugin.mypyConfigFileMap.get(config._root_path) == "~/.config/mypy/config"