Create pylint.yml (#1039)

* Create pylint.yml

* improve file matching

* fix some pylint issues

* run on PR and push (force on master only)

* more pylint fixes

* suppress noisy exit code and filter to fatals

* add conan as a dep so the module is importable

* fix lint error on unreachable branch

6 files changed, 124 insertions, 96 deletions

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 599b094..f0f0626 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -18,20 +18,20 @@ jobs:
         build_type: ['Release', 'Debug']
     steps:
     - uses: actions/checkout@v2
-      
+
     - name: create build environment
       run: cmake -E make_directory ${{ runner.workspace }}/_build
-      
+
     - name: configure cmake
       shell: bash
       working-directory: ${{ runner.workspace }}/_build
       run: cmake -DBENCHMARK_DOWNLOAD_DEPENDENCIES=ON $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-      
+
     - name: build
       shell: bash
       working-directory: ${{ runner.workspace }}/_build
       run: cmake --build . --config ${{ matrix.build_type }}
-      
+
     - name: test
       shell: bash
       working-directory: ${{ runner.workspace }}/_build
diff --git a/.github/workflows/pylint.yml b/.github/workflows/pylint.yml
new file mode 100644
index 0000000..c869674
--- /dev/null
+++ b/.github/workflows/pylint.yml
@@ -0,0 +1,26 @@
+name: pylint
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  pylint:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pylint pylint-exit conan
+    - name: Run pylint
+      run: |
+        pylint `find . -name '*.py'|xargs` || pylint-exit $?
diff --git a/bindings/python/google_benchmark/__init__.py b/bindings/python/google_benchmark/__init__.py
index c3a93bf..44531f9 100644
--- a/bindings/python/google_benchmark/__init__.py
+++ b/bindings/python/google_benchmark/__init__.py
@@ -39,27 +39,27 @@ __version__ = "0.1.0"
 
 
 def register(f=None, *, name=None):
-  if f is None:
-    return lambda f: register(f, name=name)
-  if name is None:
-    name = f.__name__
-  _benchmark.RegisterBenchmark(name, f)
-  return f
+    if f is None:
+        return lambda f: register(f, name=name)
+    if name is None:
+        name = f.__name__
+    _benchmark.RegisterBenchmark(name, f)
+    return f
 
 
 def _flags_parser(argv):
-  argv = _benchmark.Initialize(argv)
-  return app.parse_flags_with_usage(argv)
+    argv = _benchmark.Initialize(argv)
+    return app.parse_flags_with_usage(argv)
 
 
 def _run_benchmarks(argv):
-  if len(argv) > 1:
-    raise app.UsageError('Too many command-line arguments.')
-  return _benchmark.RunSpecifiedBenchmarks()
+    if len(argv) > 1:
+        raise app.UsageError('Too many command-line arguments.')
+    return _benchmark.RunSpecifiedBenchmarks()
 
 
 def main(argv=None):
-  return app.run(_run_benchmarks, argv=argv, flags_parser=_flags_parser)
+    return app.run(_run_benchmarks, argv=argv, flags_parser=_flags_parser)
 
 
 # Methods for use with custom main function.
diff --git a/bindings/python/google_benchmark/example.py b/bindings/python/google_benchmark/example.py
index e968462..0dead75 100644
--- a/bindings/python/google_benchmark/example.py
+++ b/bindings/python/google_benchmark/example.py
@@ -25,24 +25,24 @@ import google_benchmark as benchmark
 
 @benchmark.register
 def empty(state):
-  while state:
-    pass
+    while state:
+        pass
 
 
 @benchmark.register
 def sum_million(state):
-  while state:
-    sum(range(1_000_000))
+    while state:
+        sum(range(1_000_000))
 
 
 @benchmark.register
 def skipped(state):
-  if True:  # Test some predicate here.
-    state.skip_with_error('some error')
-    return  # NOTE: You must explicitly return, or benchmark will continue.
+    if True:  # Test some predicate here.
+        state.skip_with_error('some error')
+        return  # NOTE: You must explicitly return, or benchmark will continue.
 
-  ...  # Benchmark code would be here.
+    # Benchmark code would be here.
 
 
 if __name__ == '__main__':
-  benchmark.main()
+    benchmark.main()
diff --git a/setup.py b/setup.py
index a2b0b91..800a879 100644
--- a/setup.py
+++ b/setup.py
@@ -9,89 +9,91 @@ import setuptools
 from setuptools.command import build_ext
 
 
-here = os.path.dirname(os.path.abspath(__file__))
+HERE = os.path.dirname(os.path.abspath(__file__))
 
 
 IS_WINDOWS = sys.platform.startswith('win')
 
 
 def _get_version():
-  """Parse the version string from __init__.py."""
-  with open(os.path.join(here, 'bindings', 'python', 'google_benchmark', '__init__.py')) as f:
-    try:
-      version_line = next(
-          line for line in f if line.startswith('__version__'))
-    except StopIteration:
-      raise ValueError('__version__ not defined in __init__.py')
-    else:
-      ns = {}
-      exec(version_line, ns)  # pylint: disable=exec-used
-      return ns['__version__']
+    """Parse the version string from __init__.py."""
+    with open(os.path.join(
+            HERE, 'bindings', 'python', 'google_benchmark', '__init__.py')) as init_file:
+        try:
+            version_line = next(
+                line for line in init_file if line.startswith('__version__'))
+        except StopIteration:
+            raise ValueError('__version__ not defined in __init__.py')
+        else:
+            namespace = {}
+            exec(version_line, namespace)  # pylint: disable=exec-used
+            return namespace['__version__']
 
 
 def _parse_requirements(path):
-  with open(os.path.join(here, path)) as f:
-    return [
-        line.rstrip() for line in f
-        if not (line.isspace() or line.startswith('#'))
-    ]
+    with open(os.path.join(HERE, path)) as requirements:
+        return [
+            line.rstrip() for line in requirements
+            if not (line.isspace() or line.startswith('#'))
+        ]
 
 
 class BazelExtension(setuptools.Extension):
-  """A C/C++ extension that is defined as a Bazel BUILD target."""
+    """A C/C++ extension that is defined as a Bazel BUILD target."""
 
-  def __init__(self, name, bazel_target):
-    self.bazel_target = bazel_target
-    self.relpath, self.target_name = (
-        posixpath.relpath(bazel_target, '//').split(':'))
-    setuptools.Extension.__init__(self, name, sources=[])
+    def __init__(self, name, bazel_target):
+        self.bazel_target = bazel_target
+        self.relpath, self.target_name = (
+            posixpath.relpath(bazel_target, '//').split(':'))
+        setuptools.Extension.__init__(self, name, sources=[])
 
 
 class BuildBazelExtension(build_ext.build_ext):
-  """A command that runs Bazel to build a C/C++ extension."""
-
-  def run(self):
-    for ext in self.extensions:
-      self.bazel_build(ext)
-    build_ext.build_ext.run(self)
-
-  def bazel_build(self, ext):
-    with open('WORKSPACE', 'r') as f:
-      workspace_contents = f.read()
-
-    with open('WORKSPACE', 'w') as f:
-      f.write(re.sub(
-          r'(?<=path = ").*(?=",  # May be overwritten by setup\.py\.)',
-          sysconfig.get_python_inc().replace(os.path.sep, posixpath.sep),
-          workspace_contents))
-
-    if not os.path.exists(self.build_temp):
-      os.makedirs(self.build_temp)
-
-    bazel_argv = [
-        'bazel',
-        'build',
-        ext.bazel_target,
-        '--symlink_prefix=' + os.path.join(self.build_temp, 'bazel-'),
-        '--compilation_mode=' + ('dbg' if self.debug else 'opt'),
-    ]
-
-    if IS_WINDOWS:
-      # Link with python*.lib.
-      for library_dir in self.library_dirs:
-        bazel_argv.append('--linkopt=/LIBPATH:' + library_dir)
-
-    self.spawn(bazel_argv)
-
-    shared_lib_suffix = '.dll' if IS_WINDOWS else '.so'
-    ext_bazel_bin_path = os.path.join(
-        self.build_temp, 'bazel-bin',
-        ext.relpath, ext.target_name + shared_lib_suffix)
-    ext_dest_path = self.get_ext_fullpath(ext.name)
-    ext_dest_dir = os.path.dirname(ext_dest_path)
-    if not os.path.exists(ext_dest_dir):
-      os.makedirs(ext_dest_dir)
-    shutil.copyfile(ext_bazel_bin_path, ext_dest_path)
+    """A command that runs Bazel to build a C/C++ extension."""
+
+    def run(self):
+        for ext in self.extensions:
+            self.bazel_build(ext)
+        build_ext.build_ext.run(self)
+
+    def bazel_build(self, ext):
+        """Runs the bazel build to create the package."""
+        with open('WORKSPACE', 'r') as workspace:
+            workspace_contents = workspace.read()
+
+        with open('WORKSPACE', 'w') as workspace:
+            workspace.write(re.sub(
+                r'(?<=path = ").*(?=",  # May be overwritten by setup\.py\.)',
+                sysconfig.get_python_inc().replace(os.path.sep, posixpath.sep),
+                workspace_contents))
+
+        if not os.path.exists(self.build_temp):
+            os.makedirs(self.build_temp)
+
+        bazel_argv = [
+            'bazel',
+            'build',
+            ext.bazel_target,
+            '--symlink_prefix=' + os.path.join(self.build_temp, 'bazel-'),
+            '--compilation_mode=' + ('dbg' if self.debug else 'opt'),
+        ]
+
+        if IS_WINDOWS:
+            # Link with python*.lib.
+            for library_dir in self.library_dirs:
+                bazel_argv.append('--linkopt=/LIBPATH:' + library_dir)
+
+            self.spawn(bazel_argv)
+
+            shared_lib_suffix = '.dll' if IS_WINDOWS else '.so'
+            ext_bazel_bin_path = os.path.join(
+                self.build_temp, 'bazel-bin',
+                ext.relpath, ext.target_name + shared_lib_suffix)
+            ext_dest_path = self.get_ext_fullpath(ext.name)
+            ext_dest_dir = os.path.dirname(ext_dest_path)
+            if not os.path.exists(ext_dest_dir):
+                os.makedirs(ext_dest_dir)
+            shutil.copyfile(ext_bazel_bin_path, ext_dest_path)
 
 
 setuptools.setup(
@@ -106,7 +108,8 @@ setuptools.setup(
     packages=setuptools.find_packages('bindings/python'),
     install_requires=_parse_requirements('bindings/python/requirements.txt'),
     cmdclass=dict(build_ext=BuildBazelExtension),
-    ext_modules=[BazelExtension('google_benchmark._benchmark', '//bindings/python/google_benchmark:_benchmark')],
+    ext_modules=[BazelExtension(
+        'google_benchmark._benchmark', '//bindings/python/google_benchmark:_benchmark')],
     zip_safe=False,
     # PyPI package information.
     classifiers=[
diff --git a/tools/gbench/util.py b/tools/gbench/util.py
index 1f8e8e2..661c4ba 100644
--- a/tools/gbench/util.py
+++ b/tools/gbench/util.py
@@ -158,7 +158,6 @@ def run_or_load_benchmark(filename, benchmark_flags):
     ftype = check_input_file(filename)
     if ftype == IT_JSON:
         return load_benchmark_results(filename)
-    elif ftype == IT_Executable:
+    if ftype == IT_Executable:
         return run_benchmark(filename, benchmark_flags)
-    else:
-        assert False  # This branch is unreachable
+    raise ValueError('Unknown file type %s' % ftype)