[issue-47] drop element from resource tree

This commit adds a "drop_element" function to the Resource class. As the dataclass is frozen we need to return a new instance of Resource without the specified path. If the specified element has children or if it doesn't exist in the Resource a ValueError is thrown.

Signed-off-by: Meret Behrens <[email protected]>

src/opossum_lib/opossum_file.py

@@ -98,6 +98,25 @@ def element_exists_but_resource_type_differs(
             return self.children[element].type != resource_type
         return False
 
+    def drop_element(
+        self, path_to_element_to_drop: List[Tuple[str, ResourceType]]
+    ) -> Resource:
+        paths_in_resource = self.get_paths_with_resource_types()
+        if path_to_element_to_drop not in paths_in_resource:
+            raise ValueError(
+                f"Element {path_to_element_to_drop} doesn't exist in resource!"
+            )
+
+        else:
+            resource = Resource(ResourceType.TOP_LEVEL)
+            paths_in_resource.remove(path_to_element_to_drop)
+            paths_in_resource.append(path_to_element_to_drop[:-1])
+
+            for path_to_element_to_drop in paths_in_resource:
+                resource.add_path(path_to_element_to_drop)
+
+            return resource
+
     def to_dict(self) -> Union[int, Dict]:
         if not self.has_children():
             if self.type == ResourceType.FOLDER:

tests/test_opossum_file.py

@@ -125,3 +125,68 @@ def test_resource_add_path_throws_err_if_element_exists_with_different_type() ->
                 ("C", ResourceType.FILE),
             ]
         )
+
+
+def test_resource_drop_element_error() -> None:
+    resource = Resource(ResourceType.TOP_LEVEL)
+    resource.add_path(
+        [
+            ("A", ResourceType.FOLDER),
+            ("B", ResourceType.FILE),
+            ("E", ResourceType.FOLDER),
+            ("D", ResourceType.FILE),
+        ]
+    )
+
+    with pytest.raises(ValueError):
+        resource.drop_element(
+            [
+                ("A", ResourceType.FOLDER),
+                ("B", ResourceType.FILE),
+                ("C", ResourceType.FILE),
+            ]
+        )
+
+
+def test_resource_drop_element_error_not_leaf() -> None:
+    resource = Resource(ResourceType.TOP_LEVEL)
+    resource.add_path(
+        [
+            ("A", ResourceType.FOLDER),
+            ("B", ResourceType.FILE),
+            ("C", ResourceType.FOLDER),
+            ("D", ResourceType.FILE),
+        ]
+    )
+
+    with pytest.raises(ValueError):
+        resource.drop_element(
+            [
+                ("A", ResourceType.FOLDER),
+                ("B", ResourceType.FILE),
+                ("C", ResourceType.FILE),
+            ]
+        )
+
+
+def test_resource_drop_element() -> None:
+    resource = Resource(ResourceType.TOP_LEVEL)
+    resource.add_path(
+        [
+            ("A", ResourceType.FOLDER),
+            ("B", ResourceType.FILE),
+            ("C", ResourceType.FOLDER),
+        ]
+    )
+
+    resource_without_element = resource.drop_element(
+        [
+            ("A", ResourceType.FOLDER),
+            ("B", ResourceType.FILE),
+            ("C", ResourceType.FOLDER),
+        ]
+    )
+
+    assert resource_without_element.get_paths_with_resource_types() == [
+        [("A", ResourceType.FOLDER), ("B", ResourceType.FILE)]
+    ]