tests: Clean up test case importing

Move this to a helper function and return a set of test names instead of
a list.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/run-tests.py

@@ -228,16 +228,15 @@ def get_test_description(t):
         desc += " [long]"
     return desc
 
-def main():
+def import_test_cases():
     tests = []
     test_modules = []
     names = set()
     files = os.listdir(scriptsdir)
-    for t in files:
-        m = re.match(r'(test_.*)\.py$', t)
-        if m:
-            logger.debug("Import test cases from " + t)
-            mod = __import__(m.group(1))
+    re_files = (re.match(r'(test_.*)\.py$', n) for n in files)
+    test_files = (m.group(1) for m in re_files if m)
+    for t in test_files:
+        mod = __import__(t)
         test_modules.append(mod.__name__.replace('test_', '', 1))
         for key, val in mod.__dict__.items():
             if key.startswith("test_"):
@@ -249,7 +248,10 @@ def main():
                 if name in names:
                     print(f"Test case {name} defined multiple times")
                 names.add(name)
-    test_names = list(names)
+    return tests, test_modules, names
+
+def main():
+    tests, test_modules, test_names = import_test_cases()
 
     run = None