Add pylint support

README.rst

@@ -29,6 +29,7 @@ If the respective dependencies are found, the following optional providers will
 * pydocstyle_ linter for docstring style checking
 * autopep8_ for code formatting
 * YAPF_ for code formatting (preferred over autopep8)
+* pylint_ linter to detect various errors.
 
 Optional providers can be installed using the `extras` syntax. To install YAPF_ formatting for example:
 
@@ -155,3 +156,4 @@ This project is made available under the MIT License.
 .. _pyls-isort: https://github.com/paradoxxxzero/pyls-isort
 .. _pyls-black: https://github.com/rupert/pyls-black
 .. _Black: https://github.com/ambv/black
+.. _pylint: https://www.pylint.org/

pyls/hookspecs.py

@@ -88,7 +88,7 @@ def pyls_initialize(config, workspace):
 
 
 @hookspec
-def pyls_lint(config, workspace, document):
+def pyls_lint(config, workspace, document, on_change):
     pass
 
 

pyls/plugins/mccabe_lint.py

@@ -30,8 +30,8 @@ def pyls_lint(config, document):
             diags.append({
                 'source': 'mccabe',
                 'range': {
-                    'start': {'line': graph.lineno, 'character': graph.column},
-                    'end': {'line': graph.lineno, 'character': len(document.lines[graph.lineno])},
+                    'start': {'line': graph.lineno - 1, 'character': graph.column},
+                    'end': {'line': graph.lineno - 1, 'character': len(document.lines[graph.lineno])},
                 },
                 'message': 'Cyclomatic complexity too high: %s (threshold %s)' % (graph.complexity(), threshold),
                 'severity': lsp.DiagnosticSeverity.Warning

pyls/plugins/pylint_lint.py

@@ -0,0 +1,55 @@
+# Copyright 2018 SUSE, Inc.
+import os
+import logging
+import pylint.config
+import pylint.lint
+import pylint.reporters
+from pyls import hookimpl, lsp
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def pyls_lint(config, document, on_change):
+    settings = config.plugin_settings('pylint')
+    log.debug("Got pylint settings: %s", settings)
+
+    collector = DiagCollector()
+    if not on_change:
+        log.debug('Running pylint on \'%s\' in \'%s\'', document.path, os.getcwd())
+        pylint.lint.Run(args=[document.path], reporter=collector, exit=False)
+
+    return [map_diagnostic(diag, document.lines) for diag in collector.messages]
+
+
+class DiagCollector(pylint.reporters.CollectingReporter):
+
+    def display_reports(self, layout):
+        """do nothing"""
+
+    def _display(self, layout):
+        """do nothing"""
+
+
+def map_diagnostic(message, lines):
+    severity = lsp.DiagnosticSeverity.Warning
+    if message.category in ['fatal', 'error']:
+        severity = lsp.DiagnosticSeverity.Error
+
+    # LSP lines start at 0, while pylint starts at 1
+    err_range = {
+        'start': {'line': message.line - 1, 'character': message.column},
+        'end': {
+            # FIXME: It's a little naive to mark until the end of the line, can we not easily do better?
+            'line': message.line - 1,
+            'character': len(lines[message.line - 1]) - 1
+        },
+    }
+
+    return {
+        'source': 'pylint',
+        'range': err_range,
+        'message': message.msg.split('\n')[0],
+        'code': message.symbol,
+        'severity': severity
+    }

pyls/python_ls.py

@@ -194,10 +194,10 @@ def hover(self, doc_uri, position):
         return self._hook('pyls_hover', doc_uri, position=position) or {'contents': ''}
 
     @_utils.debounce(LINT_DEBOUNCE_S, keyed_by='doc_uri')
-    def lint(self, doc_uri):
+    def lint(self, doc_uri, on_change=True):
         # Since we're debounced, the document may no longer be open
         if doc_uri in self.workspace.documents:
-            self.workspace.publish_diagnostics(doc_uri, flatten(self._hook('pyls_lint', doc_uri)))
+            self.workspace.publish_diagnostics(doc_uri, flatten(self._hook('pyls_lint', doc_uri, on_change=on_change)))
 
     def references(self, doc_uri, position, exclude_declaration):
         return flatten(self._hook(
@@ -217,7 +217,7 @@ def m_text_document__did_close(self, textDocument=None, **_kwargs):
     def m_text_document__did_open(self, textDocument=None, **_kwargs):
         self.workspace.put_document(textDocument['uri'], textDocument['text'], version=textDocument.get('version'))
         self._hook('pyls_document_did_open', textDocument['uri'])
-        self.lint(textDocument['uri'])
+        self.lint(textDocument['uri'], on_change=False)
 
     def m_text_document__did_change(self, contentChanges=None, textDocument=None, **_kwargs):
         for change in contentChanges:
@@ -229,7 +229,7 @@ def m_text_document__did_change(self, contentChanges=None, textDocument=None, **
         self.lint(textDocument['uri'])
 
     def m_text_document__did_save(self, textDocument=None, **_kwargs):
-        self.lint(textDocument['uri'])
+        self.lint(textDocument['uri'], on_change=False)
 
     def m_text_document__code_action(self, textDocument=None, range=None, context=None, **_kwargs):
         return self.code_actions(textDocument['uri'], range, context)

setup.py

@@ -51,6 +51,7 @@
             'pycodestyle',
             'pydocstyle>=2.0.0',
             'pyflakes>=1.6.0',
+            'pylint',
             'rope>-0.10.5',
             'yapf',
         ],
@@ -59,6 +60,7 @@
         'pycodestyle': ['pycodestyle'],
         'pydocstyle': ['pydocstyle>=2.0.0'],
         'pyflakes': ['pyflakes>=1.6.0'],
+        'pylint': ['pylint'],
         'rope': ['rope>0.10.5'],
         'yapf': ['yapf'],
         'test': ['tox', 'versioneer', 'pytest', 'mock', 'pytest-cov', 'coverage'],
@@ -85,6 +87,7 @@
             'pycodestyle = pyls.plugins.pycodestyle_lint',
             'pydocstyle = pyls.plugins.pydocstyle_lint',
             'pyflakes = pyls.plugins.pyflakes_lint',
+            'pylint = pyls.plugins.pylint_lint',
             'rope_completion = pyls.plugins.rope_completion',
             'rope_rename = pyls.plugins.rope_rename',
             'yapf = pyls.plugins.yapf_format',

test/plugins/test_mccabe_lint.py

@@ -26,8 +26,8 @@ def test_mccabe(config):
         mod_import = [d for d in diags if d['message'] == msg][0]
 
         assert mod_import['severity'] == lsp.DiagnosticSeverity.Warning
-        assert mod_import['range']['start'] == {'line': 1, 'character': 0}
-        assert mod_import['range']['end'] == {'line': 1, 'character': 6}
+        assert mod_import['range']['start'] == {'line': 0, 'character': 0}
+        assert mod_import['range']['end'] == {'line': 0, 'character': 6}
     finally:
         config._settings = old_settings
 

test/plugins/test_pylint_lint.py

@@ -0,0 +1,80 @@
+# Copyright 2018 SUSE, Inc
+import tempfile
+import os
+import pytest
+from pyls import lsp, uris
+from pyls.workspace import Document
+from pyls.plugins import pylint_lint
+
+DOC_URI = uris.from_fs_path(__file__)
+DOC = """import sys
+
+def hello():
+\tpass
+
+import json
+"""
+
+DOC_SYNTAX_ERR = """def hello()
+    pass
+"""
+
+DOC_UNDEFINED_NAME_ERR = "a = b\n"
+
+
+@pytest.fixture
+def make_document():
+    created_files = []
+
+    def _make_document(content):
+        tmp = tempfile.NamedTemporaryFile(prefix='pylstest', mode='w', delete=False)
+        tmp.write(content)
+        tmp.close()
+        created_files.append(tmp.name)
+        return Document(uris.from_fs_path(tmp.name), content)
+
+    yield _make_document
+
+    for path in created_files:
+        os.remove(path)
+
+
+def test_pylint(config, make_document):  # pylint: disable=redefined-outer-name
+    doc = make_document(DOC)
+    diags = pylint_lint.pyls_lint(config, doc, on_change=False)
+
+    # One we're expecting is:
+    msg = 'Unused import sys'
+    unused_import = [d for d in diags if d['message'] == msg][0]
+
+    assert unused_import['range']['start'] == {'line': 0, 'character': 0}
+    assert unused_import['severity'] == lsp.DiagnosticSeverity.Warning
+    assert unused_import['code'] == 'unused-import'
+
+
+def test_pylint_onchange(config, make_document):  # pylint: disable=redefined-outer-name
+    doc = make_document(DOC)
+    diags = pylint_lint.pyls_lint(config, doc, on_change=True)
+
+    assert diags == []
+
+
+def test_syntax_error_pylint(config, make_document):  # pylint: disable=redefined-outer-name
+    doc = make_document(DOC_SYNTAX_ERR)
+    diag = pylint_lint.pyls_lint(config, doc, on_change=False)[0]
+
+    assert diag['message'] == 'invalid syntax (<string>, line 1)'
+    # sadly, pylint, always outputs column to 0 for these errors...
+    assert diag['range']['start'] == {'line': 0, 'character': 0}
+    assert diag['severity'] == lsp.DiagnosticSeverity.Error
+    assert diag['code'] == 'syntax-error'
+
+
+def test_undefined_name_pylint(config, make_document):  # pylint: disable=redefined-outer-name
+    doc = make_document(DOC_UNDEFINED_NAME_ERR)
+    diag = pylint_lint.pyls_lint(config, doc, on_change=False)[0]
+
+    assert diag['message'] == 'Undefined variable \'b\''
+    assert diag['range']['start'] == {'line': 0, 'character': 4}
+    assert diag['severity'] == lsp.DiagnosticSeverity.Error
+    assert diag['code'] == 'undefined-variable'