avocado.core.loader: Fix subtests filter

We used to support subtests filter to load only some of the avocado
tests, but the functionality is broken. This patch brings this
functionality back. It uses "re.search" so people can use partial
matches. Additionally it includes selftests to prevent future breakages.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/loader.py

@@ -487,10 +487,11 @@ class FileLoader(TestLoader):
             _url, _subtests_filter = url.split(':', 1)
             if os.path.exists(_url):  # otherwise it's ':' in the file name
                 url = _url
-                subtests_filter = _subtests_filter
+                subtests_filter = re.compile(_subtests_filter)
 
         if not os.path.isdir(url):  # Single file
-            if not self._make_tests(url, DEFAULT, subtests_filter):
+            if (not self._make_tests(url, DEFAULT, subtests_filter) and
+                    not subtests_filter):
                 split_url = shlex.split(url)
                 if (os.access(split_url[0], os.X_OK) and
                         not os.path.isdir(split_url[0])):
@@ -620,6 +621,9 @@ class FileLoader(TestLoader):
                         for test_method in test_methods:
                             name = test_name + \
                                 ':%s.%s' % (test_class, test_method)
+                            if (subtests_filter and
+                                    not subtests_filter.search(name)):
+                                continue
                             tst = (test_class, {'name': name,
                                                 'modulePath': test_path,
                                                 'methodName': test_method})

selftests/unit/test_loader.py

@@ -221,6 +221,23 @@ class LoaderTest(unittest.TestCase):
         avocado_multiple_tests.save()
         suite = self.loader.discover(avocado_multiple_tests.path, True)
         self.assertEqual(len(suite), 2)
+        # Try to load only some of the tests
+        suite = self.loader.discover(avocado_multiple_tests.path +
+                                     ':MultipleMethods.testTwo', True)
+        self.assertEqual(len(suite), 1)
+        self.assertEqual(suite[0][1]["methodName"], 'testTwo')
+        # Load using regexp
+        suite = self.loader.discover(avocado_multiple_tests.path +
+                                     ':.*_one', True)
+        self.assertEqual(len(suite), 1)
+        self.assertEqual(suite[0][1]["methodName"], 'test_one')
+        # Load booth
+        suite = self.loader.discover(avocado_multiple_tests.path +
+                                     ':test.*', True)
+        self.assertEqual(len(suite), 2)
+        # Load none should return no tests
+        self.assertTrue(not self.loader.discover(avocado_multiple_tests.path +
+                                                 ":no_match", True))
         avocado_multiple_tests.remove()
 
     def test_load_foreign(self):