Refactor direct url editable test

Author: sbidoul

src/pip/_internal/metadata/base.py

@@ -23,7 +23,6 @@
     DIRECT_URL_METADATA_NAME,
     DirectUrl,
     DirectUrlValidationError,
-    DirInfo,
 )
 from pip._internal.utils.compat import stdlib_pkgs  # TODO: Move definition here.
 from pip._internal.utils.egg_link import egg_link_path_from_sys_path
@@ -86,7 +85,7 @@ def editable_project_location(self) -> Optional[str]:
         # TODO: this property is relatively costly to compute, memoize it ?
         direct_url = self.direct_url
         if direct_url:
-            if isinstance(direct_url.info, DirInfo) and direct_url.info.editable:
+            if direct_url.is_local_editable():
                 return url_to_path(direct_url.url)
         else:
             # Search for an .egg-link file by walking sys.path, as it was

src/pip/_internal/models/direct_url.py

@@ -215,3 +215,6 @@ def from_json(cls, s: str) -> "DirectUrl":
 
     def to_json(self) -> str:
         return json.dumps(self.to_dict(), sort_keys=True)
+
+    def is_local_editable(self) -> bool:
+        return isinstance(self.info, DirInfo) and self.info.editable