support ignore config in pyproject.toml (#937)

* support ignore config in pyproject.toml

* add doc in readme

* add tests

* changelog

4 files changed, 132 insertions, 13 deletions

diff --git a/CHANGELOG b/CHANGELOG
index afe8718..a35ce68 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,11 @@
 # All notable changes to this project will be documented in this file.
 # This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.32.0] UNRELEASED
+### Added
+- Look at the 'pyproject.toml' file to see if it contains ignore file information
+  for YAPF.
+
 ## [0.31.0] 2021-03-14
 ### Added
 - Renamed 'master' brannch to 'main'.
diff --git a/README.rst b/README.rst
index 1bc7b58..b381c4d 100644
--- a/README.rst
+++ b/README.rst
@@ -136,12 +136,12 @@ otherwise (including program error). You can use this in a CI workflow to test t
 has been YAPF-formatted.
 
 ---------------------------------------------
-Excluding files from formatting (.yapfignore)
+Excluding files from formatting (.yapfignore or pyproject.toml)
 ---------------------------------------------
 
 In addition to exclude patterns provided on commandline, YAPF looks for additional
-patterns specified in a file named ``.yapfignore`` located in the working directory from
-which YAPF is invoked.
+patterns specified in a file named ``.yapfignore`` or ``pyproject.toml`` located in the
+working directory from which YAPF is invoked.
 
 ``.yapfignore``'s syntax is similar to UNIX's filename pattern matching::
 
@@ -152,6 +152,15 @@ which YAPF is invoked.
 
 Note that no entry should begin with `./`.
 
+If you use ``pyproject.toml``, exclude patterns are specified by ``ignore_pattens`` key
+in ``[tool.yapfignore]`` section. For example:
+
+.. code-block:: ini
+   [tool.yapfignore]
+   ignore_patterns="""
+   temp/**/*.py
+   temp2/*.py
+   """
 
 Formatting style
 ================
diff --git a/yapf/yapflib/file_resources.py b/yapf/yapflib/file_resources.py
index 84a8a54..4c0fbf2 100644
--- a/yapf/yapflib/file_resources.py
+++ b/yapf/yapflib/file_resources.py
@@ -32,10 +32,9 @@ LF = '\n'
 CRLF = '\r\n'
 
 
-def _GetExcludePatternsFromFile(filename):
-  """Get a list of file patterns to ignore."""
+def _GetExcludePatternsFromYapfIgnore(filename):
+  """Get a list of file patterns to ignore from .yapfignore."""
   ignore_patterns = []
-  # See if we have a .yapfignore file.
   if os.path.isfile(filename) and os.access(filename, os.R_OK):
     with open(filename, 'r') as fd:
       for line in fd:
@@ -48,6 +47,33 @@ def _GetExcludePatternsFromFile(filename):
   return ignore_patterns
 
 
+def _GetExcludePatternsFromPyprojectToml(filename):
+  """Get a list of file patterns to ignore from pyproject.toml."""
+  ignore_patterns = []
+  try:
+    import toml
+  except ImportError:
+    raise errors.YapfError(
+        "toml package is needed for using pyproject.toml as a configuration file"
+    )
+
+  pyproject_toml = toml.load(filename)
+  if os.path.isfile(filename) and os.access(filename, os.R_OK):
+    excludes = pyproject_toml.get('tool',
+                                  {}).get('yapfignore',
+                                          {}).get('ignore_patterns', None)
+  if excludes is None:
+    return []
+
+  for line in excludes.split('\n'):
+    if line.strip() and not line.startswith('#'):
+      ignore_patterns.append(line.strip())
+  if any(e.startswith('./') for e in ignore_patterns):
+    raise errors.YapfError('path in pyproject.toml should not start with ./')
+
+  return ignore_patterns
+
+
 def GetExcludePatternsForDir(dirname):
   """Return patterns of files to exclude from ignorefile in a given directory.
 
@@ -60,8 +86,16 @@ def GetExcludePatternsForDir(dirname):
     A List of file patterns to exclude if ignore file is found, otherwise empty
     List.
   """
-  ignore_file = os.path.join(dirname, '.yapfignore')
-  return _GetExcludePatternsFromFile(ignore_file)
+  ignore_patterns = []
+
+  yapfignore_file = os.path.join(dirname, '.yapfignore')
+  if os.path.exists(yapfignore_file):
+    ignore_patterns += _GetExcludePatternsFromYapfIgnore(yapfignore_file)
+
+  pyproject_toml_file = os.path.join(dirname, 'pyproject.toml')
+  if os.path.exists(pyproject_toml_file):
+    ignore_patterns += _GetExcludePatternsFromPyprojectToml(pyproject_toml_file)
+  return ignore_patterns
 
 
 def GetDefaultStyleForDir(dirname, default_style=style.DEFAULT_STYLE):
diff --git a/yapftests/file_resources_test.py b/yapftests/file_resources_test.py
index a4b1230..6afd8a4 100644
--- a/yapftests/file_resources_test.py
+++ b/yapftests/file_resources_test.py
@@ -54,16 +54,87 @@ class GetExcludePatternsForDir(unittest.TestCase):
   def tearDown(self):  # pylint: disable=g-missing-super-call
     shutil.rmtree(self.test_tmpdir)
 
-  def _make_test_dir(self, name):
-    fullpath = os.path.normpath(os.path.join(self.test_tmpdir, name))
-    os.makedirs(fullpath)
-    return fullpath
+  def test_get_exclude_file_patterns_from_yapfignore(self):
+    local_ignore_file = os.path.join(self.test_tmpdir, '.yapfignore')
+    ignore_patterns = ['temp/**/*.py', 'temp2/*.py']
+    with open(local_ignore_file, 'w') as f:
+      f.writelines('\n'.join(ignore_patterns))
 
-  def test_get_exclude_file_patterns(self):
+    self.assertEqual(
+        sorted(file_resources.GetExcludePatternsForDir(self.test_tmpdir)),
+        sorted(ignore_patterns))
+
+  def test_get_exclude_file_patterns_from_yapfignore_with_wrong_syntax(self):
     local_ignore_file = os.path.join(self.test_tmpdir, '.yapfignore')
+    ignore_patterns = ['temp/**/*.py', './wrong/syntax/*.py']
+    with open(local_ignore_file, 'w') as f:
+      f.writelines('\n'.join(ignore_patterns))
+
+    with self.assertRaises(errors.YapfError):
+      file_resources.GetExcludePatternsForDir(self.test_tmpdir)
+
+  def test_get_exclude_file_patterns_from_pyproject(self):
+    try:
+      import toml
+    except ImportError:
+      return
+    local_ignore_file = os.path.join(self.test_tmpdir, 'pyproject.toml')
     ignore_patterns = ['temp/**/*.py', 'temp2/*.py']
     with open(local_ignore_file, 'w') as f:
+      f.write('[tool.yapfignore]\n')
+      f.write('ignore_patterns="""')
+      f.writelines('\n'.join(ignore_patterns))
+      f.write('"""')
+
+    self.assertEqual(
+        sorted(file_resources.GetExcludePatternsForDir(self.test_tmpdir)),
+        sorted(ignore_patterns))
+
+  def test_get_exclude_file_patterns_from_pyproject_with_wrong_syntax(self):
+    try:
+      import toml
+    except ImportError:
+      return
+    local_ignore_file = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    ignore_patterns = ['temp/**/*.py', './wrong/syntax/*.py']
+    with open(local_ignore_file, 'w') as f:
+      f.write('[tool.yapfignore]\n')
+      f.write('ignore_patterns="""')
       f.writelines('\n'.join(ignore_patterns))
+      f.write('"""')
+
+    with self.assertRaises(errors.YapfError):
+      file_resources.GetExcludePatternsForDir(self.test_tmpdir)
+
+  def test_get_exclude_file_patterns_from_pyproject_no_ignore_section(self):
+    try:
+      import toml
+    except ImportError:
+      return
+    local_ignore_file = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    ignore_patterns = []
+    open(local_ignore_file, 'w').close()
+
+    self.assertEqual(
+        sorted(file_resources.GetExcludePatternsForDir(self.test_tmpdir)),
+        sorted(ignore_patterns))
+
+  def test_get_exclude_file_patterns_from_pyproject_ignore_section_empty(self):
+    try:
+      import toml
+    except ImportError:
+      return
+    local_ignore_file = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    ignore_patterns = []
+    with open(local_ignore_file, 'w') as f:
+      f.write('[tool.yapfignore]\n')
+
+    self.assertEqual(
+        sorted(file_resources.GetExcludePatternsForDir(self.test_tmpdir)),
+        sorted(ignore_patterns))
+
+  def test_get_exclude_file_patterns_with_no_config_files(self):
+    ignore_patterns = []
 
     self.assertEqual(
         sorted(file_resources.GetExcludePatternsForDir(self.test_tmpdir)),