Add an entry point to discover and run helpers tests with teamcity-messages

Utilize it to run tests on TC instead of plain "-m unittest discover".

GitOrigin-RevId: e021c4f5dd01f5a5b9b0d989d6befd795e394499

python/helpers/tests/__main__.py

@@ -0,0 +1,23 @@
+import os
+import sys
+import unittest
+
+_tests_dir = os.path.dirname(os.path.abspath(__file__))
+_helpers_dir = os.path.dirname(_tests_dir)
+
+
+def discover_and_run_tests():
+    suite = unittest.TestLoader().discover(_tests_dir)
+    runner = unittest.TextTestRunner()
+    try:
+        import teamcity.unittestpy
+        if teamcity.is_running_under_teamcity():
+            runner = teamcity.unittestpy.TeamcityTestRunner()
+    except ImportError:
+        pass
+    runner.run(suite)
+
+
+if __name__ == '__main__':
+    sys.path.append(_helpers_dir)
+    discover_and_run_tests()

python/helpers/tests/build.gradle

@@ -23,7 +23,7 @@ envs {
       mustRunAfter 'build_envs'
 
       environment PYTHONPATH: ".:.."
-      commandLine new File(pythonDirectory, pythonName).absolutePath + '/bin/python', '-m', 'unittest'
+      commandLine new File(pythonDirectory, pythonName).absolutePath + '/bin/python', '__main__.py'
     }
   }