Added a python unittest for step selection.

testing/adios2/bindings/python/CMakeLists.txt

@@ -15,6 +15,7 @@ endfunction()
 python_add_test(NAME Bindings.Python.HighLevelAPI.Serial SCRIPT TestHighLevelAPI.py)
 
 python_add_test(NAME Bindings.Python.BPWriteReadTypes.Serial SCRIPT TestBPWriteReadTypes_nompi.py)
+python_add_test(NAME Bindings.Python.BPSelectSteps.Serial SCRIPT TestBPSelectSteps_nompi.py)
 
 if(ADIOS2_HAVE_MPI)
   add_python_mpi_test(BPWriteReadTypes)

testing/adios2/bindings/python/TestBPSelectSteps_nompi.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+#
+# Distributed under the OSI-approved Apache License, Version 2.0.  See
+# accompanying file Copyright.txt for details.
+#
+# TestBPSelectSteps_nompi.py: test step selection by reading in Python
+# in ADIOS2 File Write
+#  Created on: Jan 29, 2021
+#      Author: Dmitry Ganyushin ganyushindi@ornl.gov
+import unittest
+import shutil
+import numpy as np
+import adios2
+
+TESTDATA_FILENAME = "steps_int32.bp"
+
+
+class TestAdiosSelectSteps(unittest.TestCase):
+
+    def setUp(self):
+        total_steps = 10
+        with adios2.open(TESTDATA_FILENAME, "w") as fh:
+            for i in range(total_steps):
+                fh.write("step", np.array([i], dtype=np.int32), [1], [0], [1])
+                fh.end_step()
+
+    def tearDown(self):
+        shutil.rmtree(TESTDATA_FILENAME)
+
+    def test_select_steps_reading_fullAPI(self):
+        selected_steps = [3, 5, 7]
+        param_string = ",".join([str(i) for i in selected_steps])
+        adios = adios2.ADIOS()
+        ioReadBP = adios.DeclareIO("hellopy")
+        ioReadBP.SetParameter(TESTDATA_FILENAME, param_string)
+        fh = ioReadBP.Open(TESTDATA_FILENAME, adios2.Mode.Read)
+        var = ioReadBP.InquireVariable("step")
+        var.SetStepSelection([0, len(selected_steps)])
+        data = np.zeros(len(selected_steps), dtype=np.int32)
+        fh.Get(var, data, adios2.Mode.Sync)
+        self.assertTrue(all([data[i] == selected_steps[i] for i in
+                             range(len(selected_steps))]))
+
+
+if __name__ == '__main__':
+    unittest.main()