From dd36e5f3bc92fdf2700c6eef5fa29315bc32ea5c Mon Sep 17 00:00:00 2001
From: rhodrin <rhodri.nelson@gmail.com>
Date: Wed, 24 Mar 2021 21:58:50 +0000
Subject: [PATCH] tests: Add initial tests for custom coefficient overhaul.

---
 tests/test_custom_coefficients.py | 73 +++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 tests/test_custom_coefficients.py

diff --git a/tests/test_custom_coefficients.py b/tests/test_custom_coefficients.py
new file mode 100644
index 0000000000..ab6865283b
--- /dev/null
+++ b/tests/test_custom_coefficients.py
@@ -0,0 +1,73 @@
+import numpy as np
+import sympy as sp
+import pytest
+
+from devito import (Grid, Function, TimeFunction, Eq,
+                    Dimension, solve, Operator, NODE)
+from devito.finite_differences import Differentiable
+from devito.tools import as_tuple
+
+_PRECISION = 9
+
+
+class TestSC(object):
+    """
+    Class for testing custom coefficients functionality
+    """
+
+    @pytest.mark.parametrize('expr, sorder, dorder, dim, weights, expected', [
+        ('u.dx', 2, 1, 0, [-0.6, 0.1, 0.6],
+         '0.1*u(x, y) - 0.6*u(x - h_x, y) + 0.6*u(x + h_x, y)'),
+        ('u.dy2', 3, 2, 1, [0.121, -0.223, 1.648, -2.904],
+         '1.648*u(x, y) + 0.121*u(x, y - 2*h_y) - 0.223*u(x, y - h_y) \
+- 2.904*u(x, y + h_y)')])
+    def test_coefficients(self, expr, sorder, dorder, dim, weights, expected):
+        """Test that custom coefficients return the expected result"""
+        grid = Grid(shape=(10, 10))
+        u = Function(name='u', grid=grid, space_order=sorder)
+
+        eq = Eq(eval(expr)(coeffs=weights))
+        assert isinstance(eq.lhs, Differentiable)
+        assert expected == str(eq.evaluate.lhs)
+
+    #def test_function_coefficients(self):
+        #"""Test that custom function coefficients return the expected result"""
+        #so = 2
+        #grid = Grid(shape=(4, 4))
+        #f0 = TimeFunction(name='f0', grid=grid, space_order=so, coefficients='symbolic')
+        #f1 = TimeFunction(name='f1', grid=grid, space_order=so)
+        #x, y = grid.dimensions
+
+        #s = Dimension(name='s')
+        #ncoeffs = so+1
+
+        #wshape = list(grid.shape)
+        #wshape.append(ncoeffs)
+        #wshape = as_tuple(wshape)
+
+        #wdims = list(grid.dimensions)
+        #wdims.append(s)
+        #wdims = as_tuple(wdims)
+
+        #w = Function(name='w', dimensions=wdims, shape=wshape)
+        #w.data[:, :, 0] = 0.0
+        #w.data[:, :, 1] = -1.0/grid.spacing[0]
+        #w.data[:, :, 2] = 1.0/grid.spacing[0]
+
+        #f_x_coeffs = Coefficient(1, f0, x, w)
+
+        #subs = Substitutions(f_x_coeffs)
+
+        #eq0 = Eq(f0.dt + f0.dx, 1, coefficients=subs)
+        #eq1 = Eq(f1.dt + f1.dx, 1)
+
+        #stencil0 = solve(eq0.evaluate, f0.forward)
+        #stencil1 = solve(eq1.evaluate, f1.forward)
+
+        #op0 = Operator(Eq(f0.forward, stencil0))
+        #op1 = Operator(Eq(f1.forward, stencil1))
+
+        #op0(time_m=0, time_M=5, dt=1.0)
+        #op1(time_m=0, time_M=5, dt=1.0)
+
+        #assert np.all(np.isclose(f0.data[:] - f1.data[:], 0.0, atol=1e-5, rtol=0))