handle empty sample

src/easyreflectometry/sample/collections/sample.py

@@ -124,18 +124,20 @@ def _enable_changes_to_outermost_layers(self):
         Superphase can change thickness and roughness.
         Subphase can change thickness.
         """
-        self.superphase.thickness.enabled = True
-        self.superphase.roughness.enabled = True
-        self.subphase.thickness.enabled = True
+        if len(self) != 0:
+            self.superphase.thickness.enabled = True
+            self.superphase.roughness.enabled = True
+            self.subphase.thickness.enabled = True
 
     def _disable_changes_to_outermost_layers(self):
         """No allowed to change the outermost layers of the sample.
         Superphase can change thickness and roughness.
         Subphase can change thickness.
         """
-        self.superphase.thickness.enabled = False
-        self.superphase.roughness.enabled = False
-        self.subphase.thickness.enabled = False
+        if len(self) != 0:
+            self.superphase.thickness.enabled = False
+            self.superphase.roughness.enabled = False
+            self.subphase.thickness.enabled = False
 
     # Representation
     def as_dict(self, skip: Optional[List[str]] = None) -> dict:

tests/model/test_model.py

@@ -337,6 +337,27 @@ def test_remove_assembly_with_interface_refl1d(self):
     #     assert_equal(len(mod.interface()._wrapper.storage['item']), 1)
     #     assert_equal(len(mod.interface()._wrapper.storage['layer']), 2)
 
+    def test_remove_all_assemblies(self):
+        # when
+        # m1 = Material(6.908, -0.278, 'Boron')
+        # m2 = Material(0.487, 0.000, 'Potassium')
+        # l1 = Layer(m1, 5.0, 2.0, 'thinBoron')
+        # l2 = Layer(m2, 50.0, 1.0, 'thickPotassium')
+        # ls1 = LayerCollection(l1, l2, name='twoLayer1')
+        # ls2 = LayerCollection(l2, l1, name='twoLayer2')
+        # o1 = RepeatingMultilayer(ls1, 2.0, 'twoLayerItem1')
+        # o2 = RepeatingMultilayer(ls2, 1.0, 'oneLayerItem2')
+        # d = Sample(o1, o2, name='myModel')
+        # resolution_function = PercentageFhwm(2.0)
+        mod = Model()
+
+        # Then
+        mod.remove_assembly(0)
+        mod.remove_assembly(0)
+
+        # Expect
+        assert_equal(len(mod.sample), 0)
+
     def test_resolution_function(self):
         mock_resolution_function = MagicMock()
         interface = CalculatorFactory()