Adding integration test for PostOpStressState feature

tests/test_PostOpStressState.py

@@ -0,0 +1,33 @@
+import pytest
+from SOSAT import StressState
+from SOSAT import PostOpStressState
+from SOSAT.constraints import FaultConstraint
+from scipy.stats import uniform
+
+def test_PostOpStressState():
+
+	# depth in meters
+	depth = 1228.3
+	# density in kg/m^3
+	avg_overburden_density = 2580.0
+	# pore pressure gradient in MPa/km
+	pore_pressure_grad = 9.955
+
+	pore_pressure = pore_pressure_grad * (1.0 / 1000) * depth
+
+	ss = StressState(depth=depth,
+	                avg_overburden_density=avg_overburden_density,
+	                pore_pressure=pore_pressure, 
+	                nbins = 50)
+
+	fc = FaultConstraint()
+	ss.add_constraint(fc)
+
+	gamma_dist = uniform(0.4,(0.6-0.4))
+	dP = 15.0 # MPa
+	postOp_ss = PostOpStressState(ss, gamma_dist, dP)
+
+	postOp_ss.evaluate_posterior()
+
+	sig = postOp_ss.posterior[20,20]
+	sig == pytest.approx(0.001829)