HOC push_section(python_section_name) does not work. (#1070)

* from neuron.expect_hocerr import expect_hocerr available for all tests.

share/lib/python/neuron/expect_hocerr.py

@@ -0,0 +1,40 @@
+import sys
+from io import StringIO
+from neuron import h
+pc = h.ParallelContext()
+nhost = pc.nhost()
+
+def expect_hocerr(callable, args, sec=None):
+  """
+  Execute callable(args) and assert that it generated an error.
+
+  If sec is not None, executes callable(args, sec=sec)
+  Skips if nhost > 1 as all hoc_execerror end in MPI_ABORT
+  Does not work well with nrniv launch since hoc_execerror messages do not
+  pass through sys.stderr.
+  """
+
+  if nhost > 1:
+    return
+
+  old_stderr = sys.stderr
+  sys.stderr = my_stderr = StringIO()
+  err = 0
+  try:
+    if sec:
+      callable(*args, sec=sec)
+    else:  
+      callable(*args)
+  except:
+    err=1
+  errmes =  my_stderr.getvalue()
+  sys.stderr = old_stderr
+  if errmes:
+    errmes = errmes.splitlines()[0]
+    errmes = errmes[(errmes.find(':')+2):]
+    print("expect_hocerr: %s" % errmes)
+  if err == 0:
+    print("expect_hocerr: no err for %s%s" % (str(callable), str(args)))
+  assert(err)
+
+

src/nrnoc/cabcode.c

@@ -2382,7 +2382,7 @@ void push_section(void) {
 		sec = (Section*)0;
 		s = gargstr(1);
 		ForAllSections(sec1) /* I can't imagine a more inefficient way */
-			if (strcmp(s, secname(sec1)) == 0) {
+			if (strcmp(s, nrn_sec2pysecname(sec1)) == 0) {
 				sec = sec1;
 				break;
 			}

test/pynrn/test_basic.py

@@ -1,4 +1,5 @@
 import sys
+from neuron.expect_hocerr import expect_hocerr
 
 import numpy as np
 
@@ -113,3 +114,27 @@ def test_newobject_err_recover():
   assert(err == 1)
   h.finitialize() # succeeds without seg fault
 
+def test_push_section():
+  h('''create hCable1, hCable2''')
+  h.push_section("hCable1")
+  assert(h.secname() == "hCable1")
+  h.pop_section()
+  h.push_section("hCable2")
+  assert(h.secname() == "hCable2")
+  h.pop_section()
+  h.delete_section(sec=h.hCable1)
+  h.delete_section(sec=h.hCable2)
+
+  sections = [h.Section(name="pCable%d"%i) for i in range(2)]
+  sections.append(h.Section()) # Anonymous in the past
+  for sec in sections:
+    name_in_hoc = h.secname(sec=sec)
+    h.push_section(name_in_hoc)
+    assert(h.secname() == name_in_hoc)
+    h.pop_section()
+  s = sections[-1]
+  h.delete_section(sec=s) # but not yet freed (though the name is now "")
+  # not [no longer] a section pointer
+  expect_hocerr(h.push_section, (int(s.hoc_internal_name().replace("__nrnsec_", ""), 0),))
+  # not a sectionname
+  expect_hocerr(h.push_section, ("not_a_sectionname",))