[bugfix] Remove the validation of the name of the test's base classes

reframe/frontend/loader.py

@@ -21,29 +21,17 @@ def __init__(self):
 
     @property
     def valid(self):
-        return self._has_import and self._has_regression_test
+        return self._has_import
 
     def visit_Import(self, node):
         for m in node.names:
             if m.name.startswith('reframe'):
                 self._has_import = True
 
     def visit_ImportFrom(self, node):
-        if node.module.startswith('reframe'):
+        if node.module is not None and node.module.startswith('reframe'):
             self._has_import = True
 
-    def visit_ClassDef(self, node):
-        for b in node.bases:
-            try:
-                # Unqualified name as in `class C(RegressionTest)`
-                cls_name = b.id
-            except AttributeError:
-                # Qualified name as in `class C(rfm.RegressionTest)`
-                cls_name = b.attr
-
-            if 'RegressionTest' in cls_name:
-                self._has_regression_test = True
-
 
 class RegressionCheckLoader:
     def __init__(self, load_path, prefix='',

unittests/resources/checks/bad/relative_imports.py

@@ -0,0 +1,7 @@
+#
+# module to test reframe's loader with relative imports
+#
+from . import invalid_iterable
+from .. import hellocheck 
+from .invalid_iterable import _get_checks
+from ..hellocheck import HelloTest