add tests, docstrings

src/rfbzero/crossover.py

@@ -10,7 +10,7 @@ class Crossover:
     Parameters
     ----------
     membrane_thickness : float
-        Membrane thickness, input units are (microns) but converted to cm
+        Membrane thickness (microns)
     permeability_ox : float
         Permeability of oxidized species through membrane (cm^2/s)
     permeability_red : float
@@ -27,7 +27,7 @@ class Crossover:
 
     def __init__(self, membrane_thickness: float, permeability_ox: float, permeability_red: float) -> None:
         """Initialize Crossover"""
-        self.membrane_thickness = membrane_thickness / 10000
+        self.membrane_thickness = membrane_thickness / 10000  # convert microns to cm
         self.permeability_ox = permeability_ox
         self.permeability_red = permeability_red
 

src/rfbzero/experiment.py

@@ -4,7 +4,7 @@
 
 from abc import ABC, abstractmethod
 from enum import Enum
-#from typing import Tuple
+# from typing import Tuple
 
 from scipy.optimize import fsolve
 

src/rfbzero/redox_flow_cell.py

@@ -17,7 +17,7 @@
 # Molar gas constant (J/K/mol)
 R = spc.R
 
-# make these parameters at some point?
+# TODO make temperature a variable
 TEMPERATURE = 298  # Kelvins, for S.T.P.
 NERNST_CONST = (R * TEMPERATURE) / F
 

tests/test_redox_flow_cell.py

@@ -44,6 +44,30 @@ def test_class_init(self, v_cls, v_ncls, ox_cls, red_cls, ox_ncls, red_ncls, ocv
                        n_ncls=n_n,
                        )
 
+    @pytest.mark.parametrize("v_cls,v_ncls,ox_cls,red_cls,ox_ncls,red_ncls,ocv,res,k_c,k_n,time_i",
+                             [(0.01, 0.05, 0.01, 0.01, 0.01, 0.01, 1, 1, 1e-3, 1e-3, 1.0),
+                              (0.01, 0.05, 0.01, 0.01, 0.01, 0.01, 1, 1, 1e-3, 1e-3, 5.0),
+                              (0.01, 0.05, 0.01, 0.01, 0.01, 0.01, 1, 1, 1e-3, 1e-3, 11.2),
+                              ])
+    def test_timestep_warning(self,v_cls,v_ncls,ox_cls,red_cls,ox_ncls,red_ncls,ocv,res,k_c,k_n,time_i,capsys):
+        ZeroDModel(cls_volume=v_cls,
+                   ncls_volume=v_ncls,
+                   cls_start_c_ox=ox_cls,
+                   cls_start_c_red=red_cls,
+                   ncls_start_c_ox=ox_ncls,
+                   ncls_start_c_red=red_ncls,
+                   init_ocv=ocv,
+                   resistance=res,
+                   k_0_cls=k_c,
+                   k_0_ncls=k_n,
+                   time_increment=time_i
+                   )
+
+        warn_out = "WARNING: 'time_increment' >= 1 second will result in very coarse data.\
+                  \nzero-D model approaches theory as timestep decreases."
+        captured = capsys.readouterr()
+        assert captured.out.strip() == warn_out
+
     def test_exchange_current(self):
         cell = ZeroDModel(cls_volume=0.005, ncls_volume=0.01, cls_start_c_ox=0.01, cls_start_c_red=0.01,
                           ncls_start_c_ox=0.01, ncls_start_c_red=0.01, init_ocv=1.0, resistance=1, k_0_cls=1e-3,