Add exclude option to pylsp-mypy configuration (#71)

* add regex pattern matching to exclude documents from type checking

* Move exclude code to pylsp_lint so mypy is not invoked unnecessarily

* Use re.search so pattern is matched across the whole path

* Improve test so we are sure the exclude section has this side-effect

* Document the exclude config option

* Make the match_exclude_patterns logic os independent

Just convert windows paths to unix (a ilke) paths, so d:\My Documents\my_file.py becomes d:/My Documents/my_file.py

Then you can reuse the configured exclude patterns for both windows and unix (a like) platforms.

* Update the TYPE_ERR_MSG to be compatible with mypy 1.7

---------

Co-authored-by: Jonas Bulik <jonas@bulik.dev>
Co-authored-by: Richard Kellnberger <Richard1.Kellnberger@web.de>

Author: 3 people

README.rst

@@ -45,6 +45,9 @@ Configuration
 ``report_progress`` (default is ``False``) report basic progress to the LSP client.
     With this option, pylsp-mypy will report when mypy is running, given your editor supports LSP progress reporting. For small files this might produce annoying flashing in your editor, especially in with ``live_mode``. For large projects, enabling this can be helpful to assure yourself whether mypy is still running.
 
+``exclude`` (default is ``[]``) A list of regular expressions which should be ignored.
+    The ``mypy`` runner wil not be invoked when a document path is matched by one of the expressions. Note that this differs from the ``exclude`` directive of a ``mypy`` config which is only used for recursively discovering files when mypy is invoked on a whole directory. For both windows or unix platforms you should use forward slashes (``/``) to indicate paths.
+
 This project supports the use of ``pyproject.toml`` for configuration. It is in fact the preferred way. Using that your configuration could look like this:
 
 ::
@@ -53,6 +56,7 @@ This project supports the use of ``pyproject.toml`` for configuration. It is in
     enabled = true
     live_mode = true
     strict = true
+    exclude = ["tests/*"]
 
 A ``pyproject.toml`` does not conflict with the legacy config file given that it does not contain a ``pylsp-mypy`` section. The following explanation uses the syntax of the legacy config file. However, all these options also apply to the ``pyproject.toml`` configuration (note the lowercase bools).
 Depending on your editor, the configuration (found in a file called pylsp-mypy.cfg in your workspace or a parent directory) should be roughly like this for a standard configuration:
@@ -62,7 +66,8 @@ Depending on your editor, the configuration (found in a file called pylsp-mypy.c
     {
         "enabled": True,
         "live_mode": True,
-        "strict": False
+        "strict": False,
+        "exclude": ["tests/*"]
     }
 
 With ``dmypy`` enabled your config should look like this:

pylsp_mypy/plugin.py

@@ -142,6 +142,21 @@ def didSettingsChange(workspace: str, settings: Dict[str, Any]) -> None:
         settingsCache[workspace] = settings.copy()
 
 
+def match_exclude_patterns(document_path: str, exclude_patterns: list) -> bool:
+    """Check if the current document path matches any of the configures exlude patterns."""
+    document_path = document_path.replace(os.sep, "/")
+
+    for pattern in exclude_patterns:
+        try:
+            if re.search(pattern, document_path):
+                log.debug(f"{document_path} matches " f"exclude pattern '{pattern}'")
+                return True
+        except re.error as e:
+            log.error(f"pattern {pattern} is not a valid regular expression: {e}")
+
+    return False
+
+
 @hookimpl
 def pylsp_lint(
     config: Config, workspace: Workspace, document: Document, is_saved: bool
@@ -181,6 +196,18 @@ def pylsp_lint(
 
     didSettingsChange(workspace.root_path, settings)
 
+    # Running mypy with a single file (document) ignores any exclude pattern
+    # configured with mypy. We can now add our own exclude section like so:
+    # [tool.pylsp-mypy]
+    # exclude = ["tests/*"]
+    exclude_patterns = settings.get("exclude", [])
+
+    if match_exclude_patterns(document_path=document.path, exclude_patterns=exclude_patterns):
+        log.debug(
+            f"Not running because {document.path} matches " f"exclude patterns '{exclude_patterns}'"
+        )
+        return []
+
     if settings.get("report_progress", False):
         with workspace.report_progress("lint: mypy"):
             return get_diagnostics(workspace, document, settings, is_saved)

test/test_plugin.py

@@ -1,10 +1,11 @@
 import collections
 import os
+import re
 import subprocess
 import sys
 from pathlib import Path
 from typing import Dict
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 
 import pytest
 from mypy import api as mypy_api
@@ -18,7 +19,12 @@
 DOC_URI = f"file:/{Path(__file__)}"
 DOC_TYPE_ERR = """{}.append(3)
 """
-TYPE_ERR_MSG = '"Dict[<nothing>, <nothing>]" has no attribute "append"'
+
+# Mypy 1.7 changed <nothing> into "Never", so make this a regex to be compatible
+# with multiple versions of mypy
+TYPE_ERR_MSG_REGEX = (
+    r'"Dict\[(?:(?:<nothing>)|(?:Never)), (?:(?:<nothing>)|(?:Never))\]" has no attribute "append"'
+)
 
 TEST_LINE = 'test_plugin.py:279:8:279:16: error: "Request" has no attribute "id"  [attr-defined]'
 TEST_LINE_NOTE = (
@@ -66,7 +72,7 @@ def test_plugin(workspace, last_diagnostics_monkeypatch):
 
     assert len(diags) == 1
     diag = diags[0]
-    assert diag["message"] == TYPE_ERR_MSG
+    assert re.fullmatch(TYPE_ERR_MSG_REGEX, diag["message"])
     assert diag["range"]["start"] == {"line": 0, "character": 0}
     # Running mypy in 3.7 produces wrong error ends this can be removed when 3.7 reaches EOL
     if sys.version_info < (3, 8):
@@ -328,3 +334,47 @@ def foo():
     diag = diags[0]
     assert diag["message"] == DOC_ERR_MSG
     assert diag["code"] == "unreachable"
+
+
+@pytest.mark.parametrize(
+    "document_path,pattern,os_sep,pattern_matched",
+    (
+        ("/workspace/my-file.py", "/someting-else", "/", False),
+        ("/workspace/my-file.py", "^/workspace$", "/", False),
+        ("/workspace/my-file.py", "/workspace", "/", True),
+        ("/workspace/my-file.py", "^/workspace(.*)$", "/", True),
+        # This is a broken regex (missing ')'), but should not choke
+        ("/workspace/my-file.py", "/((workspace)", "/", False),
+        # Windows paths are tricky with all those \\ and unintended escape,
+        # characters but they should 'just' work
+        ("d:\\a\\my-file.py", "/a", "\\", True),
+        (
+            "d:\\a\\pylsp-mypy\\pylsp-mypy\\test\\test_plugin.py",
+            "/a/pylsp-mypy/pylsp-mypy/test/test_plugin.py",
+            "\\",
+            True,
+        ),
+    ),
+)
+def test_match_exclude_patterns(document_path, pattern, os_sep, pattern_matched):
+    with patch("os.sep", new=os_sep):
+        assert (
+            plugin.match_exclude_patterns(document_path=document_path, exclude_patterns=[pattern])
+            is pattern_matched
+        )
+
+
+def test_config_exclude(tmpdir, workspace):
+    """When exclude is set in config then mypy should not run for that file."""
+    doc = Document(DOC_URI, workspace, DOC_TYPE_ERR)
+
+    plugin.pylsp_settings(workspace._config)
+    workspace.update_config({"pylsp": {"plugins": {"pylsp_mypy": {}}}})
+    diags = plugin.pylsp_lint(workspace._config, workspace, doc, is_saved=False)
+    assert re.search(TYPE_ERR_MSG_REGEX, diags[0]["message"])
+
+    # Add the path of our document to the exclude patterns
+    exclude_path = doc.path.replace(os.sep, "/")
+    workspace.update_config({"pylsp": {"plugins": {"pylsp_mypy": {"exclude": [exclude_path]}}}})
+    diags = plugin.pylsp_lint(workspace._config, workspace, doc, is_saved=False)
+    assert diags == []