add test for run_step_by_step

python/tests/test_run_metta.py

@@ -1,3 +1,4 @@
+import unittest
 from hyperon import MeTTa, Environment, E
 from test_common import HyperonTestCase
 
@@ -68,6 +69,22 @@ def test_comments(self):
         result = MeTTa(env_builder=Environment.test_env()).run(program)
         self.assertEqual('[[1]]', repr(result))
 
+    def test_run_step_by_step(self):
+        program = '''
+            (= (TupleCount $tuple) (if (== $tuple ()) 0 (+ 1 (TupleCount (cdr-atom $tuple)))))
+            (= tup (1 2))
+            (= tup (3 4 5))
+            !(match &self (= tup $t) (TupleCount $t))
+        '''
+        runner = MeTTa(env_builder=Environment.test_env())
+        i = 0
+        for _state, results in runner.run_step_by_step(program):
+            pass
+            i += 1
+        print('number of steps ' + str(i))
+        self.assertLess(i, 600)
+        self.assertEqual(len(results[0]), 2)
+
     def process_exceptions(self, results):
         for result in results:
             self.assertEqual(result, [E()])
@@ -95,3 +112,6 @@ def test_scripts(self):
         self.process_exceptions(MeTTa(env_builder=Environment.test_env()).import_file(f"{pwd}/scripts/e3_match_states.metta"))
         self.process_exceptions(MeTTa(env_builder=Environment.test_env()).import_file(f"{pwd}/scripts/f1_imports.metta"))
 
+
+if __name__ == '__main__':
+    unittest.main()