fix: new random seed not random after trace rerun

Given a test run containing multiple model-based suites
and the previous suite used a specific seed to rerun a trace
when the following suite uses 'seed=new' (default)
then the newly generated seed would always be the same

Author: JFoederer

robotmbt/suiteprocessors.py

@@ -354,9 +354,11 @@ def _init_randomiser(seed: str | int | bytes | bytearray | None):
         if isinstance(seed, str):
             seed = seed.strip()
         if str(seed).lower() == 'none':
+            random.seed()
             logger.info(
                 "Using system's random seed for trace generation. This trace cannot be rerun. Use `seed=new` to generate a reusable seed.")
         elif str(seed).lower() == 'new':
+            random.seed()
             new_seed = SuiteProcessors._generate_seed()
             logger.info(f"seed={new_seed} (use seed to rerun this trace)")
             random.seed(new_seed)

utest/test_suiteprocessors.py

@@ -31,7 +31,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import unittest
-from unittest.mock import patch
+from unittest.mock import patch, call
 
 from robotmbt.suiteprocessors import SuiteProcessors
 
@@ -48,19 +48,19 @@ def test_provided_seed_is_stripped(self, mock):
 
     def test_seed_none_keeps_system_seed(self, mock):
         SuiteProcessors._init_randomiser(None)
-        mock.assert_not_called()
+        mock.assert_called_with()
 
     def test_seed_none_as_string(self, mock):
         SuiteProcessors._init_randomiser("None")
-        mock.assert_not_called()
+        mock.assert_called_with()
 
     def test_seed_none_as_string_is_stripped(self, mock):
         SuiteProcessors._init_randomiser(" None\t")
-        mock.assert_not_called()
+        mock.assert_called_with()
 
     def test_seed_none_as_string_is_case_insensitive(self, mock):
         SuiteProcessors._init_randomiser("nOnE")
-        mock.assert_not_called()
+        mock.assert_called_with()
 
     def test_seed_new_generates_reusable_seed(self, mock):
         SuiteProcessors._init_randomiser("new")
@@ -82,6 +82,16 @@ def test_generated_seeds_have_max_2_consecutive_vowels_or_consonants(self, mock)
             self.assertNotIn('***', new_seed.translate({ord(c): '*' for c in 'aeiouy'}))
             self.assertNotIn('***', new_seed.translate({ord(c): '*' for c in 'bcdfghjklmnpqrstvwxz'}))
 
+    def test_seed_is_reset_after_using_specific_seed(self, mock):
+        """
+        added to cover the issue where, after having rerun a specific trace, the next
+        generated seed was always the same.
+        """
+        SuiteProcessors._init_randomiser("specific seed")
+        SuiteProcessors._init_randomiser("new")
+        new_seed = mock.call_args.args[0]
+        mock.assert_has_calls([call("specific seed"), call(), call(new_seed)])
+
     def _is_generated_seed(self, arg):
         """
         Generated seeds are formatted as 5 dash-separated [-] words, where