Port mpitest/test_global_rng from SLI to Python

testsuite/pytests/sli2py_mpi/mpi_test_wrapper.py

@@ -305,6 +305,35 @@ def assert_correct_results(self, tmpdirpath):
                 pd.testing.assert_frame_equal(res[0], r)
 
 
+class MPITestAssertAllRanksEqual(MPITestWrapper):
+    """
+    Assert that the results from all ranks are equal, independent of number of ranks.
+    """
+
+    def assert_correct_results(self, tmpdirpath):
+        self.collect_results(tmpdirpath)
+
+        all_res = []
+        if self._spike:
+            raise NotImplementedError("SPIKE data not supported by MPITestAssertAllRanksEqual")
+
+        if self._multi:
+            raise NotImplementedError("MULTI data not supported by MPITestAssertAllRanksEqual")
+
+        if self._other:
+            all_res = list(self._other.values())  # need to get away from dict_values to allow indexing below
+
+        assert len(all_res) == len(self._procs_lst), "Missing data for some process numbers"
+        assert len(all_res[0]) == self._procs_lst[0], "Data for first proc number does not match number of procs"
+
+        reference = all_res[0][0]
+        for res, num_ranks in zip(all_res, self._procs_lst):
+            assert len(res) == num_ranks, f"Got data for {len(res)} ranks, expected {num_ranks}."
+
+            for r in res:
+                pd.testing.assert_frame_equal(r, reference)
+
+
 class MPITestAssertCompletes(MPITestWrapper):
     """
     Test class that just confirms that the test code completes.

testsuite/pytests/sli2py_mpi/test_global_rng.py

@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+#
+# test_global_rng.py
+#
+# This file is part of NEST.
+#
+# Copyright (C) 2004 The NEST Initiative
+#
+# NEST is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# NEST is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with NEST.  If not, see <http://www.gnu.org/licenses/>.
+
+import pandas as pd
+import pytest
+from mpi_test_wrapper import MPITestAssertAllRanksEqual
+
+
+# Parametrization over the number of nodes here only to show hat it works
+@pytest.mark.skipif_incompatible_mpi
+@MPITestAssertAllRanksEqual([1, 2, 4], debug=False)
+def test_global_rng():
+    """
+    Confirm that NEST random parameter used from the Python level uses globally sync'ed RNG correctly.
+    All ranks must report identical random number sequences independent of the number of ranks.
+
+    The test compares connection data written to OTHER_LABEL.
+    """
+
+    import nest
+
+    nest.rng_seed = 12
+    p = nest.CreateParameter("uniform", {"min": 0, "max": 1})
+
+    # Uncomment one of the two for loops to provoke failure
+    # for _ in range(nest.num_processes):
+    #     p.GetValue()
+    # for _ in range(nest.Rank()):
+    #     p.GetValue()
+
+    vals = pd.DataFrame([p.GetValue() for _ in range(5)])
+    vals.to_csv(OTHER_LABEL.format(nest.num_processes, nest.Rank()), sep="\t")  # noqa: F821