stdlib `wsgiref` requires argument for `read()`
stdlib `wsgiref` requires argument for `read()`

PEP3333 says:

> A server should allow read() to be called without an argument, and
> return the remainder of the client's input stream.

However, Python standard library `wsgiref` does not allow calling `read`
without arguments. Falcon test client `falcon.testing.TestClient` uses
`wsgiref` - therefore content length should be passed an argument to
`read`.

sloria/webargs