Add py.test wizardry for running a subset of file tests. Fixes #134.

3 files changed, 54 insertions, 8 deletions

diff --git a/conftest.py b/conftest.py
new file mode 100644
index 0000000..01b04d1
--- /dev/null
+++ b/conftest.py
@@ -0,0 +1,16 @@
+"""py.test plugin configuration."""
+
+def pytest_addoption(parser):
+    """Add an option for filtering the file tests run.
+
+    This has to be done in the project root; py.test doesn't (and can't)
+    recursively look for conftest.py files until after it's parsed the command
+    line.
+    """
+    parser.addoption('--test-file-filter',
+        help='comma-separated regexes to select test files',
+        action='store',
+        type='string',
+        dest='test_file_filter',
+        default=None,
+    )
diff --git a/scss/tests/conftest.py b/scss/tests/conftest.py
new file mode 100644
index 0000000..9a3b73b
--- /dev/null
+++ b/scss/tests/conftest.py
@@ -0,0 +1,36 @@
+"""py.test plugin configuration."""
+
+import glob
+import os.path
+import re
+
+FILES_DIR = os.path.join(os.path.dirname(__file__), 'files')
+
+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.
+    """
+
+    scss_files = glob.glob(os.path.join(FILES_DIR, '*/*.scss'))
+    test_file_filter = metafunc.config.getoption('test_file_filter')
+    if test_file_filter:
+        file_filters = [
+            re.compile(filt)
+            for filt in test_file_filter.split(',')
+        ]
+
+        filtered_scss_files = []
+        for fn in scss_files:
+            relfn = os.path.relpath(fn, FILES_DIR)
+            for rx in file_filters:
+                if rx.search(relfn):
+                    filtered_scss_files.append(fn)
+                    break
+
+        scss_files = filtered_scss_files
+
+    metafunc.parametrize(
+        'scss_file_pair',
+        [(fn, fn[:-5] + '.css') for fn in scss_files])
diff --git a/scss/tests/test_files.py b/scss/tests/test_files.py
index 882a027..04e15a3 100644
--- a/scss/tests/test_files.py
+++ b/scss/tests/test_files.py
@@ -22,16 +22,10 @@ logger = logging.getLogger('scss')
 logger.setLevel(logging.ERROR)
 logger.addHandler(console)
 
-HERE = os.path.join(os.path.split(__file__)[0], 'files')
 
+def test_pair_programmatic(scss_file_pair):
+    scss_fn, css_fn = scss_file_pair
 
-@pytest.mark.parametrize(
-    ('scss_fn', 'css_fn'), [
-        (scss_fn, os.path.splitext(scss_fn)[0] + '.css')
-        for scss_fn in glob.glob(os.path.join(HERE, '*/*.scss'))
-    ]
-)
-def test_pair(scss_fn, css_fn):
     with open(scss_fn) as fh:
         source = fh.read()
     with open(css_fn) as fh: