RouteExists thrown when registering a directory and a missing file to the same route.

[na-stewart]

Describe the bug
When registering a route to a file and a directory, if the file doesn't exist a sanic_routing.exceptions.RouteExists error is raised. This may be misleading and unintended.

Code snippet

example.html does not exist in this example. The directory ./resources/web does.

app.static('/', './resources/web')
app.static('/', './resources/web/example.html')

Expected behavior
Currently, if a non existent file is registered to a route, no error is thrown on startup and any attempt to retrieve registered resource raises a FileNotFoundError: [Errno 2] No such file or directory and a 404 Not Found error is displayed in the browser. Instead of this happening, as mentioned before a sanic_routing.exceptions.RouteExists is raised on startup which may be misleading and unintended.

Environment (please complete the following information):

• OS: Ubuntu 20.04.2 LTS

[ahopkins]

This is not really a bug, and is an intended outcome. Sanic is checking to see if a file like that exists. If not, it thinks you are trying to serve from a directory. Just by looking at the path, there is no way to determine if you intend to serve a file or a directory.

I think this is the correct behavior. If anything, perhaps what you really want is an explicit method to control this:

app.static('/', './resources/web', as="dir")
app.static('/', './resources/web/example.html', as="file")

With an explicit kwarg, we would not need to run path.isfile. This is not really new behavior. If Sanic 20.12 is not functioning this way, I think that is more a problem on the earlier version than with the current.

---

A bit of behind the scenes info...

Let's look at what these two are doing:

app.static("/", "./resources/web")
# Sanic checks this, sees that it is not a file and then converts to:
# "/<__file_uri__:path>"
# meaning that it will look for anything that matches using the `path` param type

app.static('/', './resources/web/example.html')
# If this is indeed a file, Sanic knows that you meant for an explicit path "/"
# There is no ambiguity, and the path does not need to be altered
# If the file does not exist, then like the first example, it tries to convert it to a `path` type
# But, since you already have a path expansion on that base path, there is now ambiguity
# and Sanic raises RouteExists

[stale]

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