Lint session should check all changed files.

Author: Jerjou Cheng

nox.py

@@ -61,15 +61,15 @@ def list_files(folder, pattern):
                 yield os.path.join(root, filename)
 
 
-def collect_sample_dirs(start_dir, blacklist=set()):
+def collect_sample_dirs(start_dir, blacklist=set(), suffix='_test.py'):
     """Recursively collects a list of dirs that contain tests.
 
     This works by listing the contents of directories and finding
     directories that have `*_test.py` files.
     """
     # Collect all the directories that have tests in them.
     for parent, subdirs, files in os.walk(start_dir):
-        if any(f for f in files if f[-8:] == '_test.py'):
+        if any(f for f in files if f.endswith(suffix) and f not in blacklist):
             # Don't recurse further, since py.test will do that.
             del subdirs[:]
             # This dir has tests in it. yield it.
@@ -240,9 +240,14 @@ def session_lint(session):
     """Lints each sample."""
     sample_directories = session.posargs
     if not sample_directories:
-        sample_directories = collect_sample_dirs('.')
-
-    # On travis, on lint changed samples.
+        # The top-level dir isn't a sample dir - only its subdirs.
+        _, subdirs, _ = next(os.walk('.'))
+        sample_directories = (
+            sample_dir for subdir in subdirs if not subdir.startswith('.')
+            for sample_dir in collect_sample_dirs(
+                    subdir, suffix='.py', blacklist='conftest.py'))
+
+    # On travis, only lint changed samples.
     if ON_TRAVIS:
         changed_files = get_changed_files()
         sample_directories = filter_samples(