null: add a test for coord_similarity()

2 files changed, 26 insertions, 1 deletions

diff --git a/test/test_null.npz b/test/test_null.npz
index d970af4..645c102 100644
--- a/test/test_null.npz
+++ b/test/test_null.npz
diff --git a/test/test_null.py b/test/test_null.py
index 56c3031..c556c56 100644
--- a/test/test_null.py
+++ b/test/test_null.py
@@ -2,7 +2,9 @@ import os
 from unittest import TestCase
 
 import numpy as np
-from   numpy.testing import assert_allclose
+from   numpy.testing import assert_allclose, assert_equal
+
+from scipy.integrate import cumulative_trapezoid
 
 from math_utils.array_utils import array_reflect as ar
 from nr_analysis_axi import null, invars
@@ -24,3 +26,26 @@ class TestNull(TestCase):
         l = self.data['l']
 
         assert_allclose(g(l), self.data['g'], 1e-12)
+
+    def test_coord_similarity(self):
+        lapse_origin = np.sqrt(-self.data['gtt'][:, 0])
+        tau          = ar(cumulative_trapezoid(lapse_origin, self.data['t'], initial = 0.0), -1)
+        T_null       = -np.log(5.4 - tau)
+
+        g = null.null_geodesics(self.t, self.x, self.gxx, self.gtt)
+
+        lambda_max = 0.01
+        ret = null.coord_similarity(self.t, self.x, T_null, None, None, g = g,
+                                    lambda_max = lambda_max, lambda_points = 32)
+
+        # returned T_null should be the same as source in this case
+        assert_equal(ret[0], T_null)
+
+        # lambdas are from 0 - lambda_max
+        assert_allclose(ret[1][0],         0.0, 1e-12)
+        assert_allclose(ret[1][-1], lambda_max, 1e-12)
+        # lambdas are equidistant
+        assert_allclose(ret[1][1:] - ret[1][:-1], ret[1][1], 1e-12)
+
+        assert_allclose(ret[2][:-10], self.data['x_of_Tnull_lambda'], 1e-12)
+        assert_allclose(ret[3][:-10], self.data['t_of_Tnull_lambda'], 1e-12)