add Roe property check

comparison_fixtures.py

+import numpy as np
 from pytest import approx
 
 
@@ -8,3 +9,12 @@ def arrays(a, b):
 def roe_identity(states, R, Rinv):
     dState = states[:,1] - states[:,0]
     arrays(R@(Rinv@dState), dState)
+
+
+def roe_property(states, fluxes, R, Rinv, lam):
+    dState = states[:,1] - states[:,0]
+    dFlux = fluxes[:,1] - fluxes[:,0]
+
+    temp = Rinv@dState
+    temp = np.multiply(lam, temp)
+    arrays(R@temp, dFlux)

test.py

@@ -26,8 +26,8 @@ def test_roe(ctx_factory):
 
     compare.roe_identity(states, R, Rinv)
 
-    #fluxes = setup.array_from_string("4 11.2 8 8 46.4,1 2.6 1 1 7.1")
-    #compare.roe_property(states, fluxes, R, Rinv, lam)
+    fluxes = setup.array_from_string("4 1,11.2 2.6,8 1,8 1,46.4 7.1")
+    compare.roe_property(states, fluxes, R, Rinv, lam)
 
 
 def test_matvec(ctx_factory):