Add review bot tool for doc8

doc8 is a style checker for Sphinx (or other) RST documentation. doc8 is
like flake8 for reStructuredText. See https://pypi.python.org/pypi/doc8
for more information.

Testing Done:
- Uploaded a diff an .rst file as review request as saw that it added some
  "errors" of this reStructuredText file.
- Uploaded a "clean" .rst file and saw that it did no add any errors.

Reviewed at https://reviews.reviewboard.org/r/9489/

bot/reviewbot/tools/doc8.py

@@ -0,0 +1,88 @@
+"""Review Bot tool to run doc8."""
+
+from __future__ import unicode_literals
+
+import logging
+
+from reviewbot.tools import Tool
+from reviewbot.utils.process import execute, is_exe_in_path
+
+
+class Doc8Tool(Tool):
+    """Review Bot tool to run doc8."""
+
+    name = 'doc8'
+    version = '1.0'
+    description = 'Checks reStructuredText for style.'
+    timeout = 30
+    options = [
+        {
+            'name': 'max_line_length',
+            'field_type': 'django.forms.IntegerField',
+            'default': 79,
+            'field_options': {
+                'label': 'Maximum Line Length',
+                'help_text': 'The maximum line length to allow.',
+                'required': True,
+            },
+        },
+        {
+            'name': 'encoding',
+            'field_type': 'django.forms.CharField',
+            'default': 'utf-8',
+            'field_options': {
+                'label': 'Encoding',
+                'help_text': 'Encoding used for rst files.',
+                'required': True,
+            },
+        },
+    ]
+
+    def check_dependencies(self):
+        """Verify that the tool's dependencies are installed.
+
+        Returns:
+            bool:
+            True if all dependencies for the tool are satisfied. If this
+            returns False, the worker will not be listed for this Tool's queue,
+            and a warning will be logged.
+        """
+        return is_exe_in_path('doc8')
+
+    def handle_file(self, f, settings):
+        """Perform a review of a single file.
+
+        Args:
+            f (reviewbot.processing.review.File):
+                The file to process.
+
+            settings (dict):
+                Tool-specific settings.
+        """
+        if not f.dest_file.lower().endswith('.rst'):
+            # Ignore the file.
+            return
+
+        path = f.get_patched_file_path()
+
+        if not path:
+            return
+
+        output = execute(
+            [
+                'doc8', '-q',
+                '--max-line-length=%s' % settings['max_line_length'],
+                '--file-encoding=%s' % settings['encoding'],
+                path,
+            ],
+            split_lines=True,
+            ignore_errors=True)
+
+        for line in output:
+            try:
+                # Strip off the filename, since it might have colons in it.
+                line = line[len(path) + 1:]
+                line_num, message = line.split(':', 1)
+                f.comment(message.strip(), int(line_num))
+            except Exception:
+                logging.error('Cannot parse line with doc8: %s', line)

bot/setup.py

@@ -30,6 +30,7 @@
             'clang = reviewbot.tools.clang:ClangTool',
             'cppcheck = reviewbot.tools.cppcheck:CPPCheckTool',
             'cpplint = reviewbot.tools.cpplint:CPPLintTool',
+            'doc8 = reviewbot.tools.doc8:Doc8Tool',
             'flake8 = reviewbot.tools.flake8:Flake8Tool',
             'jshint = reviewbot.tools.jshint:JSHintTool',
             'pmd = reviewbot.tools.pmd:PMDTool',
@@ -47,6 +48,7 @@
         'all': [
             'buildbot>=0.8.7',
             'cpplint>=0.0.3',
+            'doc8>=0.8.0',
             'flake8>=3.3.0',
             'pycodestyle',
             'pydocstyle',

docs/reviewbot/tools/doc8.rst

@@ -0,0 +1,41 @@
+.. _tool-doc8:
+
+====
+doc8
+====
+
+DOC8_ is a style checker for Sphinx (or other) reStructuredText
+documentation. Also it has basic support for plain text.
+:command:`doc8` uses RST_LINT_ as a backend for the verification.
+
+.. _DOC8: https://pypi.python.org/pypi/doc8
+.. _RST_LINT: https://pypi.python.org/pypi/restructuredtext_lint
+
+
+Checks
+======
+
+doc8 verifies the following styles in ``.rst`` files.
+
+* Invalid rst format - D000
+* Lines should not be longer than 79 characters - D001
+
+  * RST exception: line with no whitespace except in the beginning
+  * RST exception: lines with http or https urls
+  * RST exception: literal blocks
+  * RST exception: rst target directives
+
+* No trailing whitespace - D002
+* No tabulation for indentation - D003
+* No carriage returns (use unix newlines) - D004
+* No newline at end of file - D005
+
+
+Installation
+============
+
+:command:`pydocstyle` can be installed on most systems by running::
+
+    $ pip install doc8
+
+It may also be available in your system's package manager.

docs/reviewbot/tools/index.rst

@@ -12,6 +12,7 @@ Review Bot Tools
    clang
    cppcheck
    cpplint
+   doc8
    flake8
    jshint
    pmd