Bugfix/basepath (#1716)

Working towards #1709 

I think we're almost there, some tests I did are now working properly.

Would love to get some feedback/ideas on the implementation and the
tests :)

connexion/middleware/main.py

@@ -308,6 +308,9 @@ class ConnexionMiddleware:
                 app = middleware(app)  # type: ignore
             apps.append(app)
 
+        # We sort the APIs by base path so that the most specific APIs are registered first.
+        # This is due to the way Starlette matches routes.
+        self.apis = utils.sort_apis_by_basepath(self.apis)
         for app in apps:
             if isinstance(app, SpecMiddleware):
                 for api in self.apis:

connexion/utils.py

@@ -12,9 +12,13 @@ import sys
 import typing as t
 
 import yaml
+from starlette.routing import compile_path
 
 from connexion.exceptions import TypeValidationError
 
+if t.TYPE_CHECKING:
+    from connexion.middleware.main import API
+
 
 def boolean(s):
     """
@@ -423,3 +427,63 @@ def inspect_function_arguments(function: t.Callable) -> t.Tuple[t.List[str], boo
     ]
     has_kwargs = any(p.kind == p.VAR_KEYWORD for p in parameters.values())
     return list(bound_arguments), has_kwargs
+
+
+T = t.TypeVar("T")
+
+
+@t.overload
+def sort_routes(routes: t.List[str], *, key: None = None) -> t.List[str]:
+    ...
+
+
+@t.overload
+def sort_routes(routes: t.List[T], *, key: t.Callable[[T], str]) -> t.List[T]:
+    ...
+
+
+def sort_routes(routes, *, key=None):
+    """Sorts a list of routes from most specific to least specific.
+
+    See Starlette routing documentation and implementation as this function
+    is aimed to sort according to that logic.
+    - https://www.starlette.io/routing/#route-priority
+
+    The only difference is that a `path` component is appended to each route
+    such that `/` is less specific than `/basepath` while they are technically
+    not comparable.
+    This is because it is also done by the `Mount` class internally:
+    https://github.com/encode/starlette/blob/1c1043ca0ab7126419948b27f9d0a78270fd74e6/starlette/routing.py#L388
+
+    For example, from most to least specific:
+    - /users/me
+    - /users/{username}/projects/{project}
+    - /users/{username}
+
+    :param routes: List of routes to sort
+    :param key: Function to extract the path from a route if it is not a string
+
+    :return: List of routes sorted from most specific to least specific
+    """
+
+    class SortableRoute:
+        def __init__(self, path: str) -> None:
+            self.path = path.rstrip("/")
+            if not self.path.endswith("/{path:path}"):
+                self.path += "/{path:path}"
+            self.path_regex, _, _ = compile_path(self.path)
+
+        def __lt__(self, other: "SortableRoute") -> bool:
+            return bool(other.path_regex.match(self.path))
+
+    return sorted(routes, key=lambda r: SortableRoute(key(r) if key else r))
+
+
+def sort_apis_by_basepath(apis: t.List["API"]) -> t.List["API"]:
+    """Sorts a list of APIs by basepath.
+
+    :param apis: List of APIs to sort
+
+    :return: List of APIs sorted by basepath
+    """
+    return sort_routes(apis, key=lambda api: api.base_path or "/")

pyproject.toml

@@ -97,3 +97,10 @@ asyncio_mode = "auto"
 
 [tool.isort]
 profile = "black"
+
+[tool.coverage.report]
+exclude_lines = [
+    "pragma: no cover",
+    "if t.TYPE_CHECKING:",
+    "@t.overload",
+]

tests/test_utils.py

@@ -72,3 +72,74 @@ def test_is_json_mimetype():
         "application/vnd.com.myEntreprise.v6+json; charset=UTF-8"
     )
     assert not utils.is_json_mimetype("text/html")
+
+
+def test_sort_routes():
+    routes = ["/users/me", "/users/{username}"]
+    expected = ["/users/me", "/users/{username}"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = ["/{path:path}", "/basepath/{path:path}"]
+    expected = ["/basepath/{path:path}", "/{path:path}"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = ["/", "/basepath"]
+    expected = ["/basepath", "/"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = ["/basepath/{path:path}", "/basepath/v2/{path:path}"]
+    expected = ["/basepath/v2/{path:path}", "/basepath/{path:path}"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = ["/basepath", "/basepath/v2"]
+    expected = ["/basepath/v2", "/basepath"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = ["/users/{username}", "/users/me"]
+    expected = ["/users/me", "/users/{username}"]
+    assert utils.sort_routes(routes) == expected
+
+    routes = [
+        "/users/{username}",
+        "/users/me",
+        "/users/{username}/items",
+        "/users/{username}/items/{item}",
+    ]
+    expected = [
+        "/users/me",
+        "/users/{username}/items/{item}",
+        "/users/{username}/items",
+        "/users/{username}",
+    ]
+    assert utils.sort_routes(routes) == expected
+
+    routes = [
+        "/users/{username}",
+        "/users/me",
+        "/users/{username}/items/{item}",
+        "/users/{username}/items/special",
+    ]
+    expected = [
+        "/users/me",
+        "/users/{username}/items/special",
+        "/users/{username}/items/{item}",
+        "/users/{username}",
+    ]
+    assert utils.sort_routes(routes) == expected
+
+
+def test_sort_apis_by_basepath():
+    api1 = MagicMock(base_path="/")
+    api2 = MagicMock(base_path="/basepath")
+    assert utils.sort_apis_by_basepath([api1, api2]) == [api2, api1]
+
+    api3 = MagicMock(base_path="/basepath/v2")
+    assert utils.sort_apis_by_basepath([api1, api2, api3]) == [api3, api2, api1]
+
+    api4 = MagicMock(base_path="/healthz")
+    assert utils.sort_apis_by_basepath([api1, api2, api3, api4]) == [
+        api3,
+        api2,
+        api4,
+        api1,
+    ]