Add test cases

Author: vigneswaran-chandrasekaran

brian2/groups/neurongroup.py

@@ -944,15 +944,19 @@ def resting_state(self, x0 = {}):
             Dictioary with pair of state variables and resting state values. Returned values 
             are represented in SI units.
         '''
+        # check whether the model is currently unsupported
+        if self.thresholder != {} or self.events != {}:
+            raise NotImplementedError('Event based and Neuron-specific models are currently not supported for resting state calculation')
 
         if(x0.keys() - self.equations.diff_eq_names):
-            raise KeyError("Unknown State Variable: {}".format(next(iter(x0.keys() - self.equations.diff_eq_names))))
+            raise KeyError("Unknown State Variable: {}".format(next(iter(x0.keys() - 
+            self.equations.diff_eq_names))))
 
         # Add 0 as the intial value for non-mentioned state variables in x0
         x0.update({name : 0 for name in self.equations.diff_eq_names - x0.keys()})
-        
-        return dict(zip(sorted(self.equations.diff_eq_names), root(_wrapper, list(dict(sorted(x0.items())).values()), 
-            args = (self.equations, get_local_namespace(1))).x))
+        sorted_variable_values = list(dict(sorted(x0.items())).values())
+        result = root(_wrapper, sorted_variable_values, args = (self.equations, get_local_namespace(1)))
+        return dict(zip(sorted(self.equations.diff_eq_names), result.x))
 
 def _evaluate_rhs(eqs, values, namespace=None):
         """

brian2/tests/test_neurongroup.py

@@ -1,7 +1,7 @@
 from __future__ import division
 from __future__ import absolute_import
 import uuid
-
+import sys
 import sympy
 import numpy as np
 from numpy.testing.utils import assert_raises, assert_equal
@@ -22,8 +22,8 @@
 from brian2.units.fundamentalunits import (DimensionMismatchError,
                                            have_same_dimensions)
 from brian2.units.unitsafefunctions import linspace
-from brian2.units.allunits import second, volt
-from brian2.units.stdunits import ms, mV, Hz
+from brian2.units.allunits import second, volt, umetre, siemens, ufarad
+from brian2.units.stdunits import ms, mV, Hz, cm
 from brian2.utils.logger import catch_logs
 
 from brian2.tests.utils import assert_allclose
@@ -1639,6 +1639,36 @@ def test_semantics_mod():
     assert_allclose(G.x[:], float_values % 3)
     assert_allclose(G.y[:], float_values % 3)
 
+def test_resting_value():
+    """
+    Test the resting state values of the system
+    """
+    # simple model with single dependent variable, here it is not necessary 
+    # to run the model as the resting value is certain
+    epsilon = sys.float_info.epsilon
+    El = - 100
+    tau = 1 * ms
+    eqs = ''' 
+    dv/dt = (El - v)/tau : 1
+    '''
+    grp = NeuronGroup(1, eqs, method = 'exact')
+    resting_state = grp.resting_state()
+    assert abs(resting_state['v'] - El) < epsilon * max(abs(resting_state['v']), abs(El))
+    
+    # one more example
+    area = 100 * umetre ** 2
+    g_L = 1e-2 * siemens * cm ** -2 * area
+    E_L = 1000
+    Cm = 1 * ufarad * cm ** -2 * area
+    grp = NeuronGroup(10, '''dv/dt = I_leak / Cm : volt
+                       I_leak = g_L*(E_L - v) : amp''')
+    resting_state = grp.resting_state({'v': float(10000)})
+    assert abs(resting_state['v'] - E_L) < epsilon * max(abs(resting_state['v']), abs(E_L))
+    
+    # check unsupported models are identified
+    tau = 10 * ms
+    grp = NeuronGroup(1, 'dv/dt = -v/tau : volt', threshold='v > -50*mV', reset='v = -70*mV')  
+    assert_raises(NotImplementedError, lambda: grp.resting_state())
 
 if __name__ == '__main__':
     test_set_states()
@@ -1714,3 +1744,4 @@ def test_semantics_mod():
     test_semantics_floor_division()
     test_semantics_floating_point_division()
     test_semantics_mod()
+    test_resting_value()