Adds mypy linter

.gitignore

@@ -12,6 +12,7 @@
 .tox
 .vimrc
 /.cache
+/.mypy_cache
 /.ropeproject
 /_
 /libs

dummy.py

@@ -125,3 +125,13 @@ def __init__(self, filename, lineno, names):
         Message.__init__(self, filename, lineno)
         self.message_args = (names,)
         error = 1 # noQa and some comments
+
+
+class BadTyping(Message):
+    """Test the MyPy linting."""
+
+    message = 'error: No return value expected'
+
+    def bad_method(self):  # type: () -> None
+        """Return type mismatch."""
+        return 1

pylama/lint/extensions.py

@@ -46,6 +46,12 @@
 except ImportError:
     pass
 
+try:
+    from pylama.lint.pylama_mypy import Linter
+    LINTERS['mypy'] = Linter()
+except ImportError:
+    pass
+
 
 from pkg_resources import iter_entry_points
 

pylama/lint/pylama_mypy.py

@@ -0,0 +1,88 @@
+"""MyPy support."""
+
+from mypy import api
+
+from pylama.lint import Linter as Abstract
+
+
+class _MyPyMessage(object):
+    """Parser for a single MyPy output line."""
+    types = {
+        'error': 'E',
+        'warning': 'W',
+        'note': 'N'
+    }
+
+    def __init__(self, line):
+        self.filename = None
+        self.line_num = None
+        self.column = None
+        self.text = None
+        self.note = None
+        self.message_type = None
+        self.valid = False
+
+        self._parse(line)
+
+    def _parse(self, line):
+        """Parse the output line"""
+        try:
+            result = line.split(':', maxsplit=4)
+            filename, line_num_txt, column_txt, message_type, text = result
+        except ValueError:
+            return
+
+        try:
+            self.line_num = int(line_num_txt.strip())
+            self.column = int(column_txt.strip())
+        except ValueError:
+            return
+
+        self.filename = filename
+        self.message_type = message_type.strip()
+        self.text = text.strip()
+        self.valid = True
+
+    def add_note(self, note):
+        """Add in additional information about this message"""
+        self.note = note
+
+    def to_result(self):
+        """Convert to the Linter.run return value"""
+        text = [self.text]
+        if self.note:
+            text.append(self.note)
+
+        return {
+            'lnum': self.line_num,
+            'col': self.column,
+            'text': ' - '.join(text),
+            'type': self.types.get(self.message_type, '')
+        }
+
+
+class Linter(Abstract):
+    """MyPy runner."""
+
+    @staticmethod
+    def run(path, code=None, params=None, **meta):
+        """Check code with mypy.
+
+        :return list: List of errors.
+        """
+        args = [path, '--follow-imports=skip', '--show-column-numbers']
+        stdout, stderr, status = api.run(args)
+        messages = []
+        for line in stdout.split('\n'):
+            line.strip()
+            if not line:
+                continue
+            message = _MyPyMessage(line)
+            if message.valid:
+                if message.message_type == 'note':
+                    if messages[-1].line_num == message.line_num:
+                        messages[-1].add_note(message.text)
+                else:
+                    messages.append(message)
+
+        return [m.to_result() for m in messages]

requirements-test.txt

@@ -4,3 +4,4 @@ ipdb
 pytest
 eradicate   >= 0.2
 radon       >= 1.4.2
+mypy

tests/test_config.py

@@ -28,7 +28,7 @@ def test_ignore_select():
     options.ignore = ['E301', 'D102']
     options.linters = ['pycodestyle', 'pydocstyle', 'pyflakes', 'mccabe']
     errors = run('dummy.py', options=options)
-    assert len(errors) == 31
+    assert len(errors) == 32
 
     numbers = [error.number for error in errors]
     assert 'D100' in numbers

tests/test_linters.py

@@ -52,3 +52,10 @@ def test_pydocstyle():
     assert len(options.linters) == 1
     errors = run('dummy.py', options=options)
     assert errors
+
+
+def test_mypy():
+    options = parse_options(linters=['mypy'])
+    assert len(options.linters) == 1
+    errors = run('dummy.py', options=options)
+    assert len(errors) == 1