Implemented clear for material

montepy/data_inputs/material.py

@@ -69,7 +69,7 @@ def __setitem__(self, key, value):
         try:
             node = self._libraries[key]
         except KeyError:
-            node = self._generate_default_node(key)
+            node = self._generate_default_node(key, str(value))
             self._parent()._append_param_lib(node)
             self._libraries[key] = node
         node["data"].value = str(value)
@@ -98,13 +98,13 @@ def _validate_key(key):
         return key
 
     @staticmethod
-    def _generate_default_node(key: LibraryType):
+    def _generate_default_node(key: LibraryType, val: str):
         classifier = syntax_node.ClassifierNode()
         classifier.prefix = key.value
         ret = {
             "classifier": classifier,
             "seperator": syntax_node.PaddingNode(" = "),
-            "data": syntax_node.ValueNode("", str),
+            "data": syntax_node.ValueNode(val, str),
         }
         return syntax_node.SyntaxNode("mat library", ret)
 
@@ -641,6 +641,7 @@ def append(self, nuclide_frac_pair: tuple[Nuclide, float]):
         self._check_valid_comp(nuclide_frac_pair)
         self._elements.add(nuclide_frac_pair[0].element)
         self._nuclei.add(nuclide_frac_pair[0].nucleus)
+        # node for fraction
         node = self._generate_default_node(
             float, str(nuclide_frac_pair[1]), "\n" + " " * DEFAULT_INDENT
         )
@@ -806,6 +807,13 @@ def contains(
             )
         )
 
+    def clear(self):
+        """
+        Clears all nuclide components from this material.
+        """
+        for _ in range(len(self)):
+            del self[0]
+
     def normalize(self):
         """
         Normalizes the components fractions so that they sum to 1.0.

tests/inputs/pin_cell.imcnp

@@ -0,0 +1,34 @@
+Made up PWR pin Cell Problem
+c uranium rod 
+1    1  10.0   -1     101 -102 imp:n=1
+c gas gap
+2    0           1  -2 101 -102 imp:n=1
+c cladding
+3    10 5.0     2  -3 101 -102 imp:n=1
+c water cell
+5    2  1.0    2     101 -102
+                       103 -104
+                       105 -106 imp:n=1
+
+1 CZ 0.39
+2 CZ 0.40
+3 CZ 0.46
+101 PZ -0.63
+102 PZ  0.63
+103 PX -0.63
+104 PX  0.63
+105 PY -0.63
+106 PY  0.63
+
+M1    92235.80c 0.04 
+      92238.80c 0.96
+M2     1001.80c 0.66
+       8016.80c 0.33
+M10   40090.80c 0.515
+      40091.80c 0.112
+      40092.80c 0.171
+      40094.80c 0.174
+      40096.80c 0.028
+mode n
+nps 1e3 
+

tests/test_material.py

@@ -1,7 +1,7 @@
 # Copyright 2024, Battelle Energy Alliance, LLC All Rights Reserved.
-from hypothesis import given, strategies as st, settings, HealthCheck
+from hypothesis import assume, given, note, strategies as st, settings, HealthCheck
+import pathlib
 import pytest
-from hypothesis import assume, given, note, strategies as st
 
 import montepy
 
@@ -89,6 +89,19 @@ def test_mat_get_nuclide_library(
             assert iter_key == item_key
             assert big_mat_lib.default_libraries[iter_key] == item_val
 
+    def test_mat_clear(_, big_mat_lib):
+        old_mat = big_mat_lib.clone()
+        old_len = len(big_mat_lib)
+        assert old_len > 0
+        big_mat_lib.clear()
+        assert 0 == len(big_mat_lib)
+        for part in old_mat.default_libraries:
+            assert (
+                old_mat.default_libraries[part] == big_mat_lib.default_libraries[part]
+            )
+        big_mat_lib.add_nuclide("O-16.80c", 1.0)
+        _.verify_export(big_mat_lib)
+
     def test_mat_get_nuclide_library_bad(_, big_mat_lib):
         with pytest.raises(TypeError):
             big_mat_lib.get_nuclide_library(5, "nlib")
@@ -404,6 +417,21 @@ def test_mat_long_str(_, big_material):
         str(big_material)
         repr(big_material)
 
+    @pytest.mark.parametrize("file", ["test.imcnp", "pin_cell.imcnp"])
+    def test_read_add_write(_, file):
+        problem = montepy.read_input(pathlib.Path("tests") / "inputs" / file)
+        mat = problem.materials[2]
+        mat.add_nuclide("O-16.80c", 0.3)
+        try:
+            out_file = f"mat_read_write_21ij43werr{file}"
+            problem.write_problem(out_file)
+            with open(out_file, "r") as fh:
+                for line in fh:
+                    print(line.rstrip())
+            new_problem = montepy.read_input(out_file)
+        finally:
+            pathlib.Path(out_file).unlink(True)
+
     @pytest.mark.parametrize(
         "line, mat_number, is_atom, fractions",
         [