Add more semantic tests and fix test runner

mjtest/test/tests.py

@@ -63,7 +63,7 @@ class TestSuite:
             m in TestMode.USE_TESTS_OF_OTHER[self.env.mode]:
             m = self.env.mode
         for file in sorted(os.listdir(dir)):
-            if not TestCase.has_valid_file_ending(m, file):
+            if not TestCase.has_valid_file_ending(self.env.mode, file):
                 _LOG.debug("Skip file " + file)
             elif self.env.only_incorrect_tests and file in correct_test_cases:
                 _LOG.info("Skip file {} as its test case was executed correctly the last run")
@@ -221,8 +221,8 @@ class TestCase:
 
     @classmethod
     def create_from_file(cls, env: Environment, mode: str, file: str) -> Optional['TestCase']:
-        if cls.has_valid_file_ending(mode, file):
-            return cls._test_case_class_for_file(mode, file)(env, mode, file)
+        if cls.has_valid_file_ending(env.mode, file):
+            return cls._test_case_class_for_file(env.mode, file)(env, mode, file)
         return None
 
     def name(self):