ResourceCollection.make_path() incorrectly adds trailing slash to terminal endpoints

[ngjunsiang]

ResourceCollection.make_path(part) always adds a trailing slash, even for terminal endpoints that shouldn't have one. This causes 405 Method Not Allowed errors when the client makes requests to servers with strict_slashes=True.

Problem

In interface.py, the ResourceCollection.make_path() method:

def make_path(self, part: str | None = None) -> str:
    """Create a full path for a resource collection.

    Resource collection paths always end in a /.
    """
    if part:
        return (
            f"/{self.root.make_path(self.path).strip(SLASH)}"
            f"/{part.strip(SLASH)}/"
        )
    else:
        return f"/{self.root.make_path(self.path).strip(SLASH)}/"

This unconditionally adds a trailing slash when part is provided. However, this is incorrect for terminal endpoints (like /authorization_code) that are actions, not resource collections.

Impact

When CampusSessions.from_code() calls:

resp = self.client.post(
    self.make_path("authorization_code"),
    json={"code": code}
)

It generates /sessions/campus/authorization_code/ (with trailing slash), but the Flask route is defined as POST /sessions/<provider>/authorization_code (without trailing slash).

With strict_slashes=True on the server (which is needed to avoid 308 redirects that strip headers), this results in:

405 Method Not Allowed: The method is not allowed for the requested URL.

Suggested Fix

Add an end_slash parameter to ResourceCollection.make_path(), similar to Resource.make_path():

def make_path(self, part: str | None = None, end_slash: bool = True) -> str:
    """Create a full path for a resource collection.

    Args:
        part: Optional sub-resource or action path.
        end_slash: Whether to add a trailing slash (default: True for collections).

    Returns:
        Full path for the resource collection or sub-resource.
    """
    if part:
        base = f"/{self.root.make_path(self.path).strip(SLASH)}/{part.strip(SLASH)}"
        return f"{base}/" if end_slash else base
    else:
        return f"/{self.root.make_path(self.path).strip(SLASH)}/"

Then update from_code() to use end_slash=False:

def from_code(self, code: str) -> campus.model.AuthSession:
    """Get a session using authorization code."""
    resp = self.client.post(
        self.make_path("authorization_code", end_slash=False),
        json={"code": code}
    )
    # ...

Alternative

If changing the API is too disruptive, consider adding a separate method like make_action_path() for terminal endpoints that don't need trailing slashes.