tests: Increase test coverage

- Add a `temp_workspace` context manager to simplify writing new tests.
- Add `# pragma: no cover` to unit test code paths used for skipping tests.
  These code paths are only covered when tests are skipped.
  That makes it impractical to reach full code coverage on the unit test code.
  Having full coverage of unit tests is helpful for identifying unused tests.
- Test the `octal-values` rule with a custom tag.
- Test the cli `-d` option with the `default` config.
- Test support for the `XDG_CONFIG_HOME` env var.
- Test warning message output.
- Test support for `.yamllint.yml` config files.
- Test support for `.yamllint.yaml` config files.
- Test error handling of a rule with a non-enable|disable|dict value.
- Test error handling of `ignore` with a non-pattern value.
- Test error handling of a rule `ignore` with a non-pattern value.
- Test error handling of `locale` with a non-string value.
- Test error handling of `yaml-files` with a non-list value.
- Test extending config containing `ignore`.
- Test `LintProblem.__repr__` without a rule.
- Test `LintProblem.__repr__` with a rule.

tests/test_cli.py

@@ -23,7 +23,7 @@ import sys
 import tempfile
 import unittest
 
-from tests.common import build_temp_workspace
+from tests.common import build_temp_workspace, temp_workspace
 
 from yamllint import cli
 from yamllint import config
@@ -58,7 +58,7 @@ def utf8_available():
         locale.setlocale(locale.LC_ALL, 'C.UTF-8')
         locale.setlocale(locale.LC_ALL, (None, None))
         return True
-    except locale.Error:
+    except locale.Error:  # pragma: no cover
         return False
 
 
@@ -281,6 +281,16 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(ctx.stdout, '')
         self.assertRegex(ctx.stderr, r'^invalid config: not a dict')
 
+    def test_run_with_implicit_extends_config(self):
+        path = os.path.join(self.wd, 'warn.yaml')
+
+        with RunContext(self) as ctx:
+            cli.run(('-d', 'default', '-f', 'parsable', path))
+        expected_out = ('%s:1:1: [warning] missing document start "---" '
+                        '(document-start)\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (0, expected_out, ''))
+
     def test_run_with_config_file(self):
         with open(os.path.join(self.wd, 'config'), 'w') as f:
             f.write('rules: {trailing-spaces: disable}')
@@ -320,6 +330,19 @@ class CommandLineTestCase(unittest.TestCase):
             cli.run((os.path.join(self.wd, 'a.yaml'), ))
         self.assertEqual(ctx.returncode, 1)
 
+    def test_run_with_user_xdg_config_home_in_env(self):
+        self.addCleanup(os.environ.__delitem__, 'XDG_CONFIG_HOME')
+
+        with tempfile.TemporaryDirectory('w') as d:
+            os.environ['XDG_CONFIG_HOME'] = d
+            os.makedirs(os.path.join(d, 'yamllint'))
+            with open(os.path.join(d, 'yamllint', 'config'), 'w') as f:
+                f.write('extends: relaxed')
+            with RunContext(self) as ctx:
+                cli.run(('-f', 'parsable', os.path.join(self.wd, 'warn.yaml')))
+
+        self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr), (0, '', ''))
+
     def test_run_with_user_yamllint_config_file_in_env(self):
         self.addCleanup(os.environ.__delitem__, 'YAMLLINT_CONFIG_FILE')
 
@@ -345,7 +368,7 @@ class CommandLineTestCase(unittest.TestCase):
         # as the first two runs don't use setlocale()
         try:
             locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
-        except locale.Error:
+        except locale.Error:  # pragma: no cover
             self.skipTest('locale en_US.UTF-8 not available')
         locale.setlocale(locale.LC_ALL, (None, None))
 
@@ -546,6 +569,19 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(
             (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
 
+    def test_run_format_colored_warning(self):
+        path = os.path.join(self.wd, 'warn.yaml')
+
+        with RunContext(self) as ctx:
+            cli.run((path, '--format', 'colored'))
+        expected_out = (
+            '\033[4m%s\033[0m\n'
+            '  \033[2m1:1\033[0m       \033[33mwarning\033[0m  '
+            'missing document start "---"  \033[2m(document-start)\033[0m\n'
+            '\n' % path)
+        self.assertEqual(
+            (ctx.returncode, ctx.stdout, ctx.stderr), (0, expected_out, ''))
+
     def test_run_format_github(self):
         path = os.path.join(self.wd, 'a.yaml')
 
@@ -641,3 +677,27 @@ class CommandLineTestCase(unittest.TestCase):
             '\n' % path)
         self.assertEqual(
             (ctx.returncode, ctx.stdout, ctx.stderr), (1, expected_out, ''))
+
+
+class CommandLineConfigTestCase(unittest.TestCase):
+    def test_config_file(self):
+        workspace = {'a.yml': 'hello: world\n'}
+        conf = ('---\n'
+                'extends: relaxed\n')
+
+        for conf_file in ('.yamllint', '.yamllint.yml', '.yamllint.yaml'):
+            with self.subTest(conf_file):
+                with temp_workspace(workspace):
+                    with RunContext(self) as ctx:
+                        cli.run(('-f', 'parsable', '.'))
+
+                self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                                 (0, './a.yml:1:1: [warning] missing document '
+                                     'start "---" (document-start)\n', ''))
+
+                with temp_workspace({**workspace, **{conf_file: conf}}):
+                    with RunContext(self) as ctx:
+                        cli.run(('-f', 'parsable', '.'))
+
+                self.assertEqual((ctx.returncode, ctx.stdout, ctx.stderr),
+                                 (0, '', ''))