cli: Cleanly skip broken symlinks that are ignored

Before this commit, yamllint would output "[Errno 2] No such file or
directory" when running on a directory which contained a broken symbolic
link, even if the file is set to be ignored in yamllint configuration.

This commit fixes that, and adds corresponding tests.

As a side effect this changes `yamllint.linter.run(stream, config)`, so
tools that would use this API need to filter ignored files beforehand.

Fixes #399

tests/common.py

@@ -14,8 +14,10 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import contextlib
+from io import StringIO
 import os
 import shutil
+import sys
 import tempfile
 import unittest
 
@@ -54,6 +56,33 @@ def check(self, source, conf, **kwargs):
         self.assertEqual(real_problems, expected_problems)
 
 
+class RunContext:
+    """Context manager for ``cli.run()`` to capture exit code and streams."""
+
+    def __init__(self, case):
+        self.stdout = self.stderr = None
+        self._raises_ctx = case.assertRaises(SystemExit)
+
+    def __enter__(self):
+        self._raises_ctx.__enter__()
+        self.old_sys_stdout = sys.stdout
+        self.old_sys_stderr = sys.stderr
+        sys.stdout = self.outstream = StringIO()
+        sys.stderr = self.errstream = StringIO()
+        return self
+
+    def __exit__(self, *exc_info):
+        self.stdout = self.outstream.getvalue()
+        self.stderr = self.errstream.getvalue()
+        sys.stdout = self.old_sys_stdout
+        sys.stderr = self.old_sys_stderr
+        return self._raises_ctx.__exit__(*exc_info)
+
+    @property
+    def returncode(self):
+        return self._raises_ctx.exception.code
+
+
 def build_temp_workspace(files):
     tempdir = tempfile.mkdtemp(prefix='yamllint-tests-')
 
@@ -64,6 +93,8 @@ def build_temp_workspace(files):
 
         if isinstance(content, list):
             os.mkdir(path)
+        elif isinstance(content, str) and content.startswith('symlink://'):
+            os.symlink(content[10:], path)
         else:
             mode = 'wb' if isinstance(content, bytes) else 'w'
             with open(path, mode) as f:

tests/test_cli.py

@@ -23,38 +23,11 @@
 import unittest
 from io import StringIO
 
-from tests.common import build_temp_workspace, temp_workspace
+from tests.common import build_temp_workspace, RunContext, temp_workspace
 
 from yamllint import cli, config
 
 
-class RunContext:
-    """Context manager for ``cli.run()`` to capture exit code and streams."""
-
-    def __init__(self, case):
-        self.stdout = self.stderr = None
-        self._raises_ctx = case.assertRaises(SystemExit)
-
-    def __enter__(self):
-        self._raises_ctx.__enter__()
-        self.old_sys_stdout = sys.stdout
-        self.old_sys_stderr = sys.stderr
-        sys.stdout = self.outstream = StringIO()
-        sys.stderr = self.errstream = StringIO()
-        return self
-
-    def __exit__(self, *exc_info):
-        self.stdout = self.outstream.getvalue()
-        self.stderr = self.errstream.getvalue()
-        sys.stdout = self.old_sys_stdout
-        sys.stderr = self.old_sys_stderr
-        return self._raises_ctx.__exit__(*exc_info)
-
-    @property
-    def returncode(self):
-        return self._raises_ctx.exception.code
-
-
 # Check system's UTF-8 availability
 def utf8_available():
     try:
@@ -112,6 +85,9 @@ def setUpClass(cls):
                                                        'key: other value\n',
             # empty dir
             'empty-dir': [],
+            # symbolic link
+            'symlinks/file-without-yaml-extension': '42\n',
+            'symlinks/link.yaml': 'symlink://file-without-yaml-extension',
             # non-YAML file
             'no-yaml.json': '---\n'
                             'key: value\n',
@@ -152,6 +128,7 @@ def test_find_files_recursively(self):
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/directory.yaml/empty.yml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')],
         )
 
@@ -189,6 +166,7 @@ def test_find_files_recursively(self):
              os.path.join(self.wd, 'en.yaml'),
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
         )
 
@@ -226,6 +204,8 @@ def test_find_files_recursively(self):
              os.path.join(self.wd, 'sub/directory.yaml/empty.yml'),
              os.path.join(self.wd, 'sub/directory.yaml/not-yaml.txt'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/file-without-yaml-extension'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
         )
 
@@ -247,6 +227,8 @@ def test_find_files_recursively(self):
              os.path.join(self.wd, 'sub/directory.yaml/empty.yml'),
              os.path.join(self.wd, 'sub/directory.yaml/not-yaml.txt'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/file-without-yaml-extension'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
         )
 
@@ -711,6 +693,7 @@ def test_run_list_files(self):
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/directory.yaml/empty.yml'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
         )
 
@@ -727,6 +710,7 @@ def test_run_list_files(self):
              os.path.join(self.wd, 's/s/s/s/s/s/s/s/s/s/s/s/s/s/s/file.yaml'),
              os.path.join(self.wd, 'sub/directory.yaml/not-yaml.txt'),
              os.path.join(self.wd, 'sub/ok.yaml'),
+             os.path.join(self.wd, 'symlinks/link.yaml'),
              os.path.join(self.wd, 'warn.yaml')]
         )
 

tests/test_config.py

@@ -20,7 +20,7 @@
 import unittest
 from io import StringIO
 
-from tests.common import build_temp_workspace
+from tests.common import build_temp_workspace, RunContext
 
 from yamllint import cli, config
 from yamllint.config import YamlLintConfigError
@@ -773,3 +773,33 @@ def test_run_with_ignored_from_file(self):
             './s/s/ign-trail/s/s/file2.lint-me-anyway.yaml:4:17: ' + trailing,
             './s/s/ign-trail/s/s/file2.lint-me-anyway.yaml:5:5: ' + hyphen,
         )))
+
+    def test_run_with_ignore_with_broken_symlink(self):
+        wd = build_temp_workspace({
+            'file-without-yaml-extension': '42\n',
+            'link.yaml': 'symlink://file-without-yaml-extension',
+            'link-404.yaml': 'symlink://file-that-does-not-exist',
+        })
+        backup_wd = os.getcwd()
+        os.chdir(wd)
+
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', '.'))
+        self.assertNotEqual(ctx.returncode, 0)
+
+        with open(os.path.join(wd, '.yamllint'), 'w') as f:
+            f.write('extends: default\n'
+                    'ignore: |\n'
+                    '  *404.yaml\n')
+        with RunContext(self) as ctx:
+            cli.run(('-f', 'parsable', '.'))
+        self.assertEqual(ctx.returncode, 0)
+        docstart = '[warning] missing document start "---" (document-start)'
+        out = '\n'.join(sorted(ctx.stdout.splitlines()))
+        self.assertEqual(out, '\n'.join((
+            './.yamllint:1:1: ' + docstart,
+            './link.yaml:1:1: ' + docstart,
+        )))
+
+        os.chdir(backup_wd)
+        shutil.rmtree(wd)

yamllint/cli.py

@@ -30,7 +30,8 @@ def find_files_recursively(items, conf):
             for root, _dirnames, filenames in os.walk(item):
                 for f in filenames:
                     filepath = os.path.join(root, f)
-                    if conf.is_yaml_file(filepath):
+                    if (conf.is_yaml_file(filepath) and
+                            not conf.is_file_ignored(filepath)):
                         yield filepath
         else:
             yield item
@@ -209,8 +210,7 @@ def run(argv=None):
 
     if args.list_files:
         for file in find_files_recursively(args.files, conf):
-            if not conf.is_file_ignored(file):
-                print(file)
+            print(file)
         sys.exit(0)
 
     max_level = 0

yamllint/linter.py

@@ -222,9 +222,6 @@ def run(input, conf, filepath=None):
     :param input: buffer, string or stream to read from
     :param conf: yamllint configuration object
     """
-    if filepath is not None and conf.is_file_ignored(filepath):
-        return ()
-
     if isinstance(input, (bytes, str)):
         return _run(input, conf, filepath)
     elif isinstance(input, io.IOBase):