When running in an environment that freezes string literals by default, `hybi.rb` raises exceptions as it modifies the `'C2'` string.
Adding the magic comment supports this use case without modifying behavior for anyone else. I added it to one spec too, so that running specs this way (`RUBYOPT="--enable=frozen-string-literal" rspec`) keeps them all passing.
We're seeing this occasionally in our error logs, where the `env`
passed into to the driver will return a frozen string when read.
The stack trace always includes ActionCable in to the mix, so
something like this:
"/app/vendor/bundle/ruby/2.6.0/gems/websocket-driver-0.7.0/lib/websocket/driver/draft76.rb" line 11 in force_encoding
"/app/vendor/bundle/ruby/2.6.0/gems/websocket-driver-0.7.0/lib/websocket/driver/draft76.rb" line 11 in initialize
"/app/vendor/bundle/ruby/2.6.0/gems/websocket-driver-0.7.0/lib/websocket/driver.rb" line 162 in new
"/app/vendor/bundle/ruby/2.6.0/gems/websocket-driver-0.7.0/lib/websocket/driver.rb" line 162 in rack
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/connection/client_socket.rb" line 47 in initialize
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/connection/web_socket.rb" line 10 in new
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/connection/web_socket.rb" line 10 in initialize
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/connection/base.rb" line 59 in new
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/connection/base.rb" line 59 in initialize
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/server/base.rb" line 30 in new
"/app/vendor/bundle/ruby/2.6.0/gems/actioncable-5.2.3/lib/action_cable/server/base.rb" line 30 in call
I still don't quite know why someone is sometimes returning a frozen
string (it could also have to with any of the current rack middleware
we're using), but I do know that we can handle it here.
So this adds a spec and some behavior to fix that.
James Coglan
Kuba Suder
Mark Young
Tiago
Daniel Morrison
timcraft
Matti Paksula
pjaspers