Adds isSyncing to provider (#62)

ethers/provider.nim

@@ -157,6 +157,9 @@ method subscribe*(provider: Provider,
 method unsubscribe*(subscription: Subscription) {.base, async.} =
   doAssert false, "not implemented"
 
+method isSyncing*(provider: Provider): Future[bool] {.base, async.} =
+  doAssert false, "not implemented"
+
 proc replay*(provider: Provider, tx: Transaction, blockNumber: UInt256) {.async.} =
   # Replay transaction at block. Useful for fetching revert reasons, which will
   # be present in the raised error message. The replayed block number should

ethers/providers/jsonrpc.nim

@@ -222,6 +222,10 @@ method unsubscribe(subscription: JsonRpcSubscription) {.async.} =
     let id = subscription.id
     await subscriptions.unsubscribe(id)
 
+method isSyncing*(provider: JsonRpcProvider): Future[bool] {.async.} =
+  let response = await provider.send("eth_syncing")
+  return response.getBool()
+
 method close*(provider: JsonRpcProvider) {.async.} =
   convertError:
     let client = await provider.client

testmodule/providers/jsonrpc/testJsonRpcProvider.nim

@@ -99,3 +99,8 @@ for url in ["ws://localhost:8545", "http://localhost:8545"]:
         discard await provider.subscribe(proc(_: Block) = discard)
       expect JsonRpcProviderError:
         discard await provider.getSigner().sendTransaction(Transaction.example)
+
+    test "syncing":
+      let isSyncing = await provider.isSyncing()
+      check not isSyncing
+