Make sure that blueprints with no slash is maintained when applied

sanic/blueprints.py

@@ -85,7 +85,11 @@ def __init__(
         self.routes: List[Route] = []
         self.statics: List[RouteHandler] = []
         self.strict_slashes = strict_slashes
-        self.url_prefix = url_prefix
+        self.url_prefix = (
+            url_prefix[:-1]
+            if url_prefix and url_prefix.endswith("/")
+            else url_prefix
+        )
         self.version = version
         self.websocket_routes: List[Route] = []
 

sanic/mixins/routes.py

@@ -71,7 +71,7 @@ def route(
 
         # Fix case where the user did not prefix the URL with a /
         # and will probably get confused as to why it's not working
-        if not uri.startswith("/"):
+        if not uri.startswith("/") and (uri or hasattr(self, "router")):
             uri = "/" + uri
 
         if strict_slashes is None:

tests/test_routes.py

@@ -1175,3 +1175,59 @@ async def handler(request):
 
     with pytest.raises(SanicException):
         app.router.finalize()
+
+
+def test_routes_with_and_without_slash_definitions(app):
+    bar = Blueprint("bar", url_prefix="bar")
+    baz = Blueprint("baz", url_prefix="/baz")
+    fizz = Blueprint("fizz", url_prefix="fizz/")
+    buzz = Blueprint("buzz", url_prefix="/buzz/")
+
+    instances = (
+        (app, "foo"),
+        (bar, "bar"),
+        (baz, "baz"),
+        (fizz, "fizz"),
+        (buzz, "buzz"),
+    )
+
+    for instance, term in instances:
+        route = f"/{term}" if isinstance(instance, Sanic) else ""
+
+        @instance.get(route, strict_slashes=True)
+        def get_without(request):
+            return text(f"{term}_without")
+
+        @instance.get(f"{route}/", strict_slashes=True)
+        def get_with(request):
+            return text(f"{term}_with")
+
+        @instance.post(route, strict_slashes=True)
+        def post_without(request):
+            return text(f"{term}_without")
+
+        @instance.post(f"{route}/", strict_slashes=True)
+        def post_with(request):
+            return text(f"{term}_with")
+
+    app.blueprint(bar)
+    app.blueprint(baz)
+    app.blueprint(fizz)
+    app.blueprint(buzz)
+
+    for _, term in instances:
+        _, response = app.test_client.get(f"/{term}")
+        assert response.status == 200
+        assert response.text == f"{term}_without"
+
+        _, response = app.test_client.get(f"/{term}/")
+        assert response.status == 200
+        assert response.text == f"{term}_with"
+
+        _, response = app.test_client.post(f"/{term}")
+        assert response.status == 200
+        assert response.text == f"{term}_without"
+
+        _, response = app.test_client.post(f"/{term}/")
+        assert response.status == 200
+        assert response.text == f"{term}_with"