feat: instantiate with upgrader

[jacobheun]

As part of the migration to async await, and in order to add better flexibility to libp2p connection upgrades, Transports will now take, and be required to support using an Upgrader instance.

Upgraders have 2 methods: upgradeOutbound and upgradeInbound.

• upgradeOutbound must be called and returned by transport.dial.
• upgradeInbound must be called and the results must be passed to the createListener handlerFunction and the connection event handler, anytime a new connection is created.

const connection = await upgrader.upgradeOutbound({ source, sink, conn, remoteAddr })
const connection = await upgrader.upgradeInbound({ source, sink, conn, remoteAddr })

The Upgrader methods will return interface-connection instances, the new API for which is being solidified at libp2p/interface-connection#29.

[jacobheun]

@alanshaw if this looks good my thought for testing is to just add spies on the upgrader to verify the methods are called, and return a { sink, source } object as that's all that should be needed for testing. Transport tests shouldn't care about interface-connection, and returning the original { sink, source } should enable us to do stream verification.

cc: @vasco-santos

[alanshaw]

LGTM - just one suggestion

[alanshaw]

Do you think it's worth creating a definition of { source, sink, conn, remoteAddr } as MultiaddrConnection somewhere so we can refer to it better here?

[jacobheun]

Yes, I was thinking interface-connection initially, but I think it's better in the readme here since it's specific to transports.

[jacobheun]

@alanshaw @vasco-santos I have added tests to dial and listen. Test setup now takes options, and Transports will need to pass those to their constructors in test setup (the readme has been updated).

The tests now validate the respective spies are called, and that the connections returned from the transport (both dial and listen), are the same values returned by the upgrader spies.

I did some quick hacks locally on the existing libp2p-tcp async branch to ensure these tests are running properly.

[jacobheun]

This has been released as 0.6.0.