This update includes fixes for our `block-ref` and `retry-on-empty`
middleware.
The `block-ref` middleware resolves the block reference `latest` to a
specific block number, the latest one we are aware of. This is meant to
protect against situations where the network gives inconsistent answers
for what the latest block number is due to some nodes being out-of-sync
with each other (this was a frequent problem years ago with Infura).
It was broken in that the `latest` resolution was failing, and we were
submitting an additional redundant request to Infura for each request.
The `retry-on-empty` middleware is meant to retry certain methods
when they return an empty response. This was also meant to deal with
network synchronization issues that were more common years ago. This
middleware works by making a "child" request over and over until either
a retry limit is reached, or a non-empty response is received.
It was broken in that the final response recieved was thrown away, so
it's as though the middleware was not used. Except that it did result
in additional redundant network requests.
As a result of this update we should see that the extension is more
resilient to certain network synchronization issues. But this is
difficult to test, and these issues may not happen in production
anymore today.
We should see a reduction in requests to Infura as well. This should
be easier to test.
Add tests for the `block-tracker-inspector` middleware — which makes
sure that the block tracker never has a reference to the latest block
which is less than a block number that shows up in an RPC method's
response — and the Infura middleware — which takes care of sending the
request to Infura, and will retry the request up to 5 times if Infura
sends back a certain type of error.
Note that the `retry-on-empty` middleware is not tested because it
currently has a [bug][1] which is making it ineffective.
[1]: https://github.com/MetaMask/eth-json-rpc-middleware/issues/139
We are working on migrating the extension to a unified network
controller, but before we do so we want to extract some of the existing
pieces, specifically `createInfuraClient` and `createJsonRpcClient`,
which provide the majority of the behavior exhibited within the provider
API that the existing NetworkController exposes. This necessitates that
we understand and test that behavior as a whole.
With that in mind, this commit starts with the Infura-specific network
client and adds some initial functional tests for `createInfuraClient`,
specifically covering three pieces of middleware provided by
`eth-json-rpc-middleware`: `createNetworkAndChainIdMiddleware`,
`createBlockCacheMiddleware`, and `createBlockRefMiddleware`.
These tests exercise logic that originate from multiple different places
and combine in sometimes surprising ways, and as a result, understanding
the nature of the tests can be tricky. I've tried to explain the logic
(both of the implementation and the tests) via comments. Additionally,
debugging why a certain test is failing is not the most fun thing in the
world, so to aid with this, I've added some logging to the underlying
packages used when a request passes through the middleware stack.
Because some middleware change the request being made, or make new
requests altogether, this greatly helps to peel back the curtain, as
failures from Nock do not supply much meaningful information on their
own. This logging is disabled by default, but can be activated by
setting `DEBUG=metamask:*,eth-query DEBUG_COLORS=1` alongside the `jest`
command.
We use this logging by bumping `eth-block-tracker`, and
`eth-json-rpc-middleware`.
Mark Stacey
Elliot Winkler