From 3351918394cad106ce6ca35fa3fc4b53a2389e87 Mon Sep 17 00:00:00 2001
From: Patrick Shriwise <pshriwise@gmail.com>
Date: Sat, 17 Sep 2022 11:32:24 -0500
Subject: [PATCH] Adding a histogram filter test. Testing conversion from
 Tabulated1D for many interpolation types

---
 .../filter_energyfun/inputs_true.dat           | 10 ++++++++++
 .../regression_tests/filter_energyfun/test.py  | 18 +++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/tests/regression_tests/filter_energyfun/inputs_true.dat b/tests/regression_tests/filter_energyfun/inputs_true.dat
index 133b3167f2..db7f91ed08 100644
--- a/tests/regression_tests/filter_energyfun/inputs_true.dat
+++ b/tests/regression_tests/filter_energyfun/inputs_true.dat
@@ -54,6 +54,11 @@
     <y>0.2 0.7 0.7 0.2</y>
     <interpolation>cubic</interpolation>
   </filter>
+  <filter id="9" type="energyfunction">
+    <energy>0.0 5000000.0 10000000.0 15000000.0</energy>
+    <y>0.2 0.7 0.7 0.2</y>
+    <interpolation>histogram</interpolation>
+  </filter>
   <tally id="1">
     <nuclides>Am241</nuclides>
     <scores>(n,gamma)</scores>
@@ -93,4 +98,9 @@
     <nuclides>Am241</nuclides>
     <scores>(n,gamma)</scores>
   </tally>
+  <tally id="9">
+    <filters>9</filters>
+    <nuclides>Am241</nuclides>
+    <scores>(n,gamma)</scores>
+  </tally>
 </tallies>
diff --git a/tests/regression_tests/filter_energyfun/test.py b/tests/regression_tests/filter_energyfun/test.py
index 4a42ce0cb4..489eec8c07 100644
--- a/tests/regression_tests/filter_energyfun/test.py
+++ b/tests/regression_tests/filter_energyfun/test.py
@@ -28,6 +28,7 @@ def model():
     # Make an EnergyFunctionFilter directly from the x and y lists.
     filt1 = openmc.EnergyFunctionFilter(x, y)
 
+    # check interpolatoin property setter
     assert filt1.interpolation == 'linear-linear'
 
     with pytest.raises(ValueError):
@@ -60,7 +61,10 @@ def model():
     filt8 = openmc.EnergyFunctionFilter(x, y)
     filt8.interpolation = 'cubic'
 
-    filters = [filt1, filt3, filt4, filt5, filt6, filt7, filt8]
+    filt9 = openmc.EnergyFunctionFilter(x, y)
+    filt9.interpolation = 'histogram'
+
+    filters = [filt1, filt3, filt4, filt5, filt6, filt7, filt8, filt9]
     # Make tallies
     tallies = [openmc.Tally() for _ in range(len(filters) + 1)]
     for t in tallies:
@@ -72,6 +76,14 @@ def model():
 
     model.tallies.extend(tallies)
 
+    interpolation_vals = \
+    list(openmc.EnergyFunctionFilter.INTERPOLATION_SCHEMES.keys())
+    for i_val in interpolation_vals:
+        # breakpoint here is fake and unused
+        t1d = openmc.data.Tabulated1D(x, y, breakpoints=[1], interpolation=[i_val])
+        f = openmc.EnergyFunctionFilter.from_tabulated1d(t1d)
+        assert f.interpolation == openmc.EnergyFunctionFilter.INTERPOLATION_SCHEMES[i_val]
+
     return model
 
 
@@ -143,6 +155,10 @@ class FilterEnergyFunHarness(PyAPITestHarness):
         assert all(contrived_lin_lin_tally.mean < contrived_quadratic_tally.mean)
         assert all(contrived_lin_lin_tally.mean < contrived_cubic_tally.mean)
 
+        # check that the histogram tally is less than the quadratic/cubic interpolations
+        histogram_tally = sp.get_tally(id=9)
+        assert all(histogram_tally.mean < contrived_quadratic_tally.mean)
+        assert all(histogram_tally.mean < contrived_cubic_tally.mean)
 
 def test_filter_energyfun(model):
     harness = FilterEnergyFunHarness('statepoint.5.h5', model)