Revamp py.test's handling of test files.

Each .scss file is now its own test -- you can run them directly, with
`py.test scss/tests/files/foo/bar.scss`, or use wildcards, or specify a
partial directory, or whatever.

Accordingly, `test_files.py` is gone, as is the `--test-file-filter`
option that was so cumbersome I never actually used it.

Regressions:
- xfail is no longer supported.
- Ruby tests are now not collected at all, rather than marked as
  skipped.

3 files changed, 102 insertions, 139 deletions

diff --git a/conftest.py b/conftest.py
index 445657d..8019aa8 100644
--- a/conftest.py
+++ b/conftest.py
@@ -1,4 +1,27 @@
 """py.test plugin configuration."""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import logging
+
+import pytest
+
+import scss
+import scss.config
+
+try:
+    import fontforge
+except ImportError:
+    fontforge = None
+
+
+# Turn on pyscss's logging
+console = logging.StreamHandler()
+logger = logging.getLogger('scss')
+logger.setLevel(logging.ERROR)
+logger.addHandler(console)
+
 
 def pytest_addoption(parser):
     """Add options for filtering which file tests run.
@@ -7,16 +30,87 @@ def pytest_addoption(parser):
     recursively look for conftest.py files until after it's parsed the command
     line.
     """
-    parser.addoption('--include-ruby',
+    parser.addoption(
+        '--include-ruby',
         help='run tests imported from Ruby and sassc, most of which fail',
         action='store_true',
         dest='include_ruby',
     )
 
-    parser.addoption('--test-file-filter',
-        help='comma-separated regexes to select test files',
-        action='store',
-        type='string',
-        dest='test_file_filter',
-        default=None,
-    )
+
+def pytest_ignore_collect(path, config):
+    # Ruby/sassc tests don't even exist without this option
+    if path.basename in ('from_ruby', 'from-sassc'):
+        if not config.getoption('include_ruby'):
+            return True
+
+
+def pytest_collect_file(path, parent):
+    if path.ext == '.scss':
+        parts = str(path).split(path.sep)
+        # -4 tests / -3 files / -2 directory / -1 file.scss
+        if parts[-4:-2] == ['tests', 'files']:
+            return SassFile(path, parent)
+
+
+class SassFile(pytest.File):
+    def collect(self):
+        parent_name = self.fspath.dirpath().basename
+        if not fontforge and parent_name == 'fonts':
+            pytest.skip("font tests require fontforge")
+
+        yield SassItem(str(self.fspath), self)
+
+
+class SassItem(pytest.Item):
+    """A Sass test input file, collected as its own test item.
+
+    A file of the same name but with a .css extension is assumed to contain the
+    expected output.
+    """
+    _nodeid = None
+
+    @property
+    def nodeid(self):
+        # Rig the nodeid to be "directory::filename", so all the files in the
+        # same directory are treated as grouped together
+        if not self._nodeid:
+            self._nodeid = "{0}::{1}".format(
+                self.fspath.dirpath().relto(self.session.fspath),
+                self.fspath.basename,
+            )
+        return self._nodeid
+
+    def reportinfo(self):
+        return (
+            self.fspath.dirpath(),
+            None,
+            self.fspath.relto(self.session.fspath),
+        )
+
+    def runtest(self):
+        scss_file = self.fspath
+        css_file = scss_file.new(ext='css')
+
+        with scss_file.open('rb') as fh:
+            source = fh.read()
+        with css_file.open('rb') as fh:
+            # Output is Unicode, so decode this here
+            expected = fh.read().decode('utf8')
+
+        scss.config.STATIC_ROOT = str(scss_file.dirpath('static'))
+
+        compiler = scss.Scss(
+            scss_opts=dict(style='expanded'),
+            search_paths=[
+                str(scss_file.dirpath('include')),
+                str(scss_file.dirname),
+            ],
+        )
+        actual = compiler.compile(source)
+
+        # Normalize leading and trailing newlines
+        actual = actual.strip('\n')
+        expected = expected.strip('\n')
+
+        assert expected == actual
diff --git a/scss/tests/conftest.py b/scss/tests/conftest.py
deleted file mode 100644
index b2036ff..0000000
--- a/scss/tests/conftest.py
+++ /dev/null
@@ -1,81 +0,0 @@
-"""py.test plugin configuration."""
-
-import glob
-import os.path
-import re
-
-import pytest
-
-try:
-    import fontforge
-except ImportError:
-    fontforge = None
-
-FILES_DIR = os.path.relpath(os.path.join(os.path.dirname(__file__), 'files'))
-
-# Globals, yuck!  Populated below.
-test_file_tuples = None
-test_file_ids = None
-
-
-def pytest_configure(config):
-    """Scan for test files.  Done here because other hooks tend to run once
-    *per test*, and there's no reason to do this work more than once.
-    """
-    global test_file_tuples
-    global test_file_ids
-
-    include_ruby = config.getoption('include_ruby')
-    test_file_filter = config.getoption('test_file_filter')
-    if test_file_filter:
-        file_filters = [
-            re.compile(filt)
-            for filt in test_file_filter.split(',')
-        ]
-    else:
-        file_filters = []
-
-    # Tuples are 3-tuples of the form (scss filename, css filename, pytest
-    # marker).  That last one is used to carry xfail/skip, and is None for
-    # regular tests.
-    # "ids" are just names for the tests, in a parellel list.  We just use
-    # relative paths to the input file.
-    test_file_tuples = []
-    test_file_ids = []
-    for fn in glob.glob(os.path.join(FILES_DIR, '*%s*.scss' % os.sep)):
-        if os.path.basename(fn)[0] == '_':
-            continue
-
-        relfn = os.path.relpath(fn, FILES_DIR)
-        pytest_trigger = None
-
-        if relfn.startswith(('from-sassc' + os.sep, 'from-ruby' + os.sep)):
-            pytest_trigger = pytest.mark.skipif(
-                not include_ruby, reason="skipping ruby tests by default")
-        elif relfn.startswith('xfail' + os.sep):
-            pytest_trigger = pytest.mark.xfail
-        elif relfn.startswith('fonts' + os.sep):
-            pytest_trigger = pytest.mark.skipif(
-                not fontforge, reason="font tests require fontforge")
-
-        if file_filters and not any(rx.search(relfn) for rx in file_filters):
-            pytest_trigger = pytest.mark.skipif(
-                reason="skipping due to --test-file-filter")
-
-        pair = (fn, fn[:-5] + '.css')
-        if pytest_trigger:
-            pair = pytest_trigger(pair)
-
-        test_file_tuples.append(pair)
-        test_file_ids.append(fn)
-
-
-def pytest_generate_tests(metafunc):
-    """Inject the test files as parametrizations.
-
-    Relies on the command-line option `--test-file-filter`, set by the root
-    conftest.py.
-    """
-
-    if 'scss_file_pair' in metafunc.fixturenames:
-        metafunc.parametrize('scss_file_pair', test_file_tuples, ids=test_file_ids)
diff --git a/scss/tests/test_files.py b/scss/tests/test_files.py
deleted file mode 100644
index eaaba4c..0000000
--- a/scss/tests/test_files.py
+++ /dev/null
@@ -1,50 +0,0 @@
-"""Evaluates all the tests that live in `scss/tests/files`.
-
-A test is any file with a `.scss` extension.  It'll be compiled, and the output
-will be compared to the contents of a file named `foo.css`.
-
-Currently, test files must be nested exactly one directory below `files/`.
-This limitation is completely arbitrary. Files starting with '_' are skipped.
-
-"""
-
-from __future__ import absolute_import, unicode_literals
-
-import os.path
-import logging
-
-import six
-
-import scss
-
-
-if six.PY2:
-    from io import open
-
-
-console = logging.StreamHandler()
-logger = logging.getLogger('scss')
-logger.setLevel(logging.ERROR)
-logger.addHandler(console)
-
-
-def test_pair_programmatic(scss_file_pair):
-    scss_fn, css_fn = scss_file_pair
-
-    with open(scss_fn, 'rb') as fh:
-        source = fh.read()
-    with open(css_fn, 'r', encoding='utf8') as fh:
-        expected = fh.read()
-
-    directory, _ = os.path.split(scss_fn)
-    include_dir = os.path.join(directory, 'include')
-    scss.config.STATIC_ROOT = os.path.join(directory, 'static')
-
-    compiler = scss.Scss(scss_opts=dict(style='expanded'), search_paths=[include_dir, directory])
-    actual = compiler.compile(source)
-
-    # Normalize leading and trailing newlines
-    actual = actual.strip('\n')
-    expected = expected.strip('\n')
-
-    assert expected == actual