Fix with_suffix re-encoding entire name

CHANGES/1468.bugfix.rst

@@ -0,0 +1 @@
+Fix entire name being re-encoded when using `with_suffix` -- by :user:`NTFSvolume`.

tests/test_url.py

@@ -1514,6 +1514,30 @@ def test_with_suffix():
     assert url2.path == "/a/b.c"
 
 
+def test_with_suffix_encoded_suffix():
+    url = URL("http://example.com/a/b")
+    url2 = url.with_suffix(". c")
+    assert url2.raw_parts == ("/", "a", "b.%20c")
+    assert url2.parts == ("/", "a", "b. c")
+    assert url2.raw_path == "/a/b.%20c"
+    assert url2.path == "/a/b. c"
+
+
+def test_with_suffix_encoded_url():
+    url = URL("http://example.com/a/b c")
+    url2 = url.with_suffix(". d")
+    url3 = url.with_suffix(".e")
+    assert url2.raw_parts == ("/", "a", "b%20c.%20d")
+    assert url2.parts == ("/", "a", "b c. d")
+    assert url2.raw_path == "/a/b%20c.%20d"
+    assert url2.path == "/a/b c. d"
+
+    assert url3.raw_parts == ("/", "a", "b%20c.e")
+    assert url3.parts == ("/", "a", "b c.e")
+    assert url3.raw_path == "/a/b%20c.e"
+    assert url3.path == "/a/b c.e"
+
+
 @pytest.mark.parametrize(
     ("original_url", "keep_query", "keep_fragment", "expected_url"),
     [
@@ -1641,7 +1665,7 @@ def test_with_suffix_with_slash2():
     with pytest.raises(ValueError) as excinfo:
         URL("http://example.com/a").with_suffix(".b/.d")
     (msg,) = excinfo.value.args
-    assert msg == "Slash in name is not allowed"
+    assert msg == "Invalid suffix '.b/.d'"
 
 
 def test_with_suffix_replace():

yarl/_url.py

@@ -1355,15 +1355,31 @@ def with_suffix(
         """
         if not isinstance(suffix, str):
             raise TypeError("Invalid suffix type")
-        if suffix and not suffix[0] == "." or suffix == ".":
+        if suffix and not suffix[0] == "." or suffix == "." or "/" in suffix:
             raise ValueError(f"Invalid suffix {suffix!r}")
         name = self.raw_name
         if not name:
             raise ValueError(f"{self!r} has an empty name")
         old_suffix = self.raw_suffix
+        suffix = PATH_QUOTER(suffix)
         name = name + suffix if not old_suffix else name[: -len(old_suffix)] + suffix
+        if name in (".", ".."):
+            raise ValueError(". and .. values are forbidden")
+        parts = list(self.raw_parts)
+        if netloc := self._netloc:
+            if len(parts) == 1:
+                parts.append(name)
+            else:
+                parts[-1] = name
+            parts[0] = ""  # replace leading '/'
+        else:
+            parts[-1] = name
+            if parts[0] == "/":
+                parts[0] = ""  # replace leading '/'
 
-        return self.with_name(name, keep_query=keep_query, keep_fragment=keep_fragment)
+        query = self._query if keep_query else ""
+        fragment = self._fragment if keep_fragment else ""
+        return from_parts(self._scheme, netloc, "/".join(parts), query, fragment)
 
     def join(self, url: "URL") -> "URL":
         """Join URLs