Fix(material): Fixed thermal scattering law never being written to file.

Fix bug with how thermal scattering law data is not written to file: fixes: #395.

Author: MicahGale

montepy/data_inputs/material.py

@@ -116,6 +116,21 @@ def cells(self):
                 if cell.material == self:
                     yield cell
 
+    def format_for_mcnp_input(self, mcnp_version):
+        """
+        Creates a string representation of this MCNP_Object that can be
+        written to file.
+
+        :param mcnp_version: The tuple for the MCNP version that must be exported to.
+        :type mcnp_version: tuple
+        :return: a list of strings for the lines that this input will occupy.
+        :rtype: list
+        """
+        lines = super().format_for_mcnp_input(mcnp_version)
+        if self.thermal_scattering is not None:
+            lines += self.thermal_scattering.format_for_mcnp_input(mcnp_version)
+        return lines
+
     def add_thermal_scattering(self, law):
         """
         Adds thermal scattering law to the material

tests/test_integration.py

@@ -138,6 +138,10 @@ def test_write_to_file(self):
             for i, data in enumerate(self.simple_problem.data_inputs):
                 if isinstance(data, material.Material):
                     self.assertEqual(data.number, test_problem.data_inputs[i].number)
+                    if data.thermal_scattering is not None:
+                        assert (
+                            test_problem.data_inputs[i].thermal_scattering is not None
+                        )
                 elif isinstance(data, volume.Volume):
                     self.assertEqual(str(data), str(test_problem.data_inputs[i]))
                 else: