TypedPath.py (#24 closes #23)

Author: nedtwigg

python/selfie-lib/selfie_lib/TypedPath.py

@@ -0,0 +1,73 @@
+from functools import total_ordering
+
+
+@total_ordering
+class TypedPath:
+    def __init__(self, absolute_path: str):
+        self.absolute_path = absolute_path
+
+    @property
+    def name(self) -> str:
+        if self.absolute_path.endswith("/"):
+            path = self.absolute_path[:-1]
+        else:
+            path = self.absolute_path
+        last_slash = path.rfind("/")
+        return path[last_slash + 1 :]
+
+    @property
+    def is_folder(self) -> bool:
+        return self.absolute_path.endswith("/")
+
+    def assert_folder(self) -> None:
+        if not self.is_folder:
+            raise AssertionError(
+                f"Expected {self} to be a folder but it doesn't end with `/`"
+            )
+
+    def parent_folder(self) -> "TypedPath":
+        if self.absolute_path == "/":
+            raise ValueError("Path does not have a parent folder")
+        trimmed_path = self.absolute_path.rstrip("/")
+        last_idx = trimmed_path.rfind("/")
+        return TypedPath.of_folder(trimmed_path[: last_idx + 1])
+
+    def resolve_file(self, child: str) -> "TypedPath":
+        self.assert_folder()
+        if child.startswith("/") or child.endswith("/"):
+            raise ValueError("Child path is not valid for file resolution")
+        return self.of_file(f"{self.absolute_path}{child}")
+
+    def resolve_folder(self, child: str) -> "TypedPath":
+        self.assert_folder()
+        if child.startswith("/"):
+            raise ValueError("Child path starts with a slash")
+        return self.of_folder(f"{self.absolute_path}{child}/")
+
+    def relativize(self, child: "TypedPath") -> str:
+        self.assert_folder()
+        if not child.absolute_path.startswith(self.absolute_path):
+            raise ValueError(f"Expected {child} to start with {self.absolute_path}")
+        return child.absolute_path[len(self.absolute_path) :]
+
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, TypedPath):
+            return NotImplemented
+        return self.absolute_path == other.absolute_path
+
+    def __lt__(self, other: "TypedPath") -> bool:
+        return self.absolute_path < other.absolute_path
+
+    @classmethod
+    def of_folder(cls, path: str) -> "TypedPath":
+        unix_path = path.replace("\\", "/")
+        if not unix_path.endswith("/"):
+            unix_path += "/"
+        return cls(unix_path)
+
+    @classmethod
+    def of_file(cls, path: str) -> "TypedPath":
+        unix_path = path.replace("\\", "/")
+        if unix_path.endswith("/"):
+            raise ValueError("Expected path to not end with a slash for a file")
+        return cls(unix_path)

python/selfie-lib/tests/TypedPath_test.py

@@ -0,0 +1,89 @@
+import pytest
+from selfie_lib.TypedPath import TypedPath
+
+
+def test_initialization():
+    path = TypedPath("/home/user/")
+    assert path.absolute_path == "/home/user/"
+    assert path.is_folder
+    assert path.name == "user"
+
+
+def test_parent_folder():
+    path = TypedPath("/home/user/documents/")
+    parent = path.parent_folder()
+    assert isinstance(parent, TypedPath)
+    assert parent.absolute_path == "/home/user/"
+
+
+def test_resolve_file():
+    folder = TypedPath("/home/user/")
+    file = folder.resolve_file("document.txt")
+    assert file.absolute_path == "/home/user/document.txt"
+    assert not file.is_folder
+    assert file.name == "document.txt"
+
+
+def test_resolve_folder():
+    folder = TypedPath("/home/user/")
+    subfolder = folder.resolve_folder("documents")
+    assert subfolder.absolute_path == "/home/user/documents/"
+    assert subfolder.is_folder
+    assert subfolder.name == "documents"
+
+
+def test_relativize():
+    folder = TypedPath("/home/user/")
+    file = TypedPath("/home/user/document.txt")
+    relative_path = folder.relativize(file)
+    assert relative_path == "document.txt"
+
+
+def test_of_folder_class_method():
+    folder = TypedPath.of_folder("/home/user/documents")
+    assert folder.absolute_path == "/home/user/documents/"
+    assert folder.is_folder
+
+
+def test_of_file_class_method():
+    file = TypedPath.of_file("/home/user/document.txt")
+    assert file.absolute_path == "/home/user/document.txt"
+    assert not file.is_folder
+
+
+def test_assert_folder_failure():
+    with pytest.raises(AssertionError):
+        file = TypedPath("/home/user/document.txt")
+        file.assert_folder()
+
+
+def test_parent_folder_failure():
+    with pytest.raises(ValueError):
+        path = TypedPath("/")
+        path.parent_folder()
+
+
+def test_equality():
+    path1 = TypedPath("/home/user/")
+    path2 = TypedPath("/home/user/")
+    assert path1 == path2
+
+
+def test_inequality():
+    path1 = TypedPath("/home/user/")
+    path2 = TypedPath("/home/another_user/")
+    assert path1 != path2
+
+
+def test_ordering():
+    path1 = TypedPath("/home/a/")
+    path2 = TypedPath("/home/b/")
+    assert path1 < path2
+    assert path2 > path1
+
+
+def test_relativize_error():
+    parent = TypedPath("/home/user/")
+    child = TypedPath("/home/another_user/document.txt")
+    with pytest.raises(ValueError):
+        parent.relativize(child)