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metamask-extension/app/scripts/controllers/network/createJsonRpcClient.js
Zachary Belford cd2249f193
Add tests for custom JSON-RPC network client (#16337)
Previously we had written tests for `createInfuraClient`, which creates a middleware stack designed to connect to an Infura provider. These tests exercise various RPC methods that relate to the behavior that the middleware provides (mainly around caching). 

Now we need to write the same tests but for `createJsonRpcClient`, which creates a middleware stack designed to connect to a non-Infura RPC endpoint. To do this, we had to:

- Consolidate the tests for both types of RPC client into a single test file.
- Add conditions around tests or assertions in tests to account for differences in behavior between the two sets of middleware stacks.
- Relocate code in `createJsonRpcClient` which slows down `eth_estimateGas` calls just for tests so that this behavior can be disabled in the network client tests.

Eventually, as we unify the network controllers in this repo and in the core repo, we will move these tests into the core repo.

Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>
2023-01-06 10:10:17 -07:00

62 lines
1.8 KiB
JavaScript

import { createAsyncMiddleware, mergeMiddleware } from 'json-rpc-engine';
import {
createFetchMiddleware,
createBlockRefRewriteMiddleware,
createBlockCacheMiddleware,
createInflightCacheMiddleware,
createBlockTrackerInspectorMiddleware,
providerFromMiddleware,
} from 'eth-json-rpc-middleware';
import { PollingBlockTracker } from 'eth-block-tracker';
import { SECOND } from '../../../../shared/constants/time';
export default function createJsonRpcClient({ rpcUrl, chainId }) {
const blockTrackerOpts = process.env.IN_TEST
? { pollingInterval: SECOND }
: {};
const fetchMiddleware = createFetchMiddleware({ rpcUrl });
const blockProvider = providerFromMiddleware(fetchMiddleware);
const blockTracker = new PollingBlockTracker({
...blockTrackerOpts,
provider: blockProvider,
});
const testMiddlewares = process.env.IN_TEST
? [createEstimateGasDelayTestMiddleware()]
: [];
const networkMiddleware = mergeMiddleware([
...testMiddlewares,
createChainIdMiddleware(chainId),
createBlockRefRewriteMiddleware({ blockTracker }),
createBlockCacheMiddleware({ blockTracker }),
createInflightCacheMiddleware(),
createBlockTrackerInspectorMiddleware({ blockTracker }),
fetchMiddleware,
]);
return { networkMiddleware, blockTracker };
}
function createChainIdMiddleware(chainId) {
return (req, res, next, end) => {
if (req.method === 'eth_chainId') {
res.result = chainId;
return end();
}
return next();
};
}
/**
* For use in tests only.
* Adds a delay to `eth_estimateGas` calls.
*/
function createEstimateGasDelayTestMiddleware() {
return createAsyncMiddleware(async (req, _, next) => {
if (req.method === 'eth_estimateGas') {
await new Promise((resolve) => setTimeout(resolve, SECOND * 2));
}
return next();
});
}