clients/viem: use interval for routine fetching, unref intervalId

integrations/viem-v2/package.json

@@ -29,7 +29,7 @@
 		"lint": "biome check .",
 		"format": "biome format --write .",
 		"clean": "rm -rf dist",
-		"test": "vitest --run",
+		"test": "vitest --run && timeout -k 5s 2s pnpm ts-node ./scripts/test.js",
 		"build": "npm run build:cjs && npm run build:esm && npm run build:types",
 		"build:cjs": "tsc --project ./tsconfig.build.json --module commonjs --outDir ./dist/_cjs --removeComments --verbatimModuleSyntax false && printf '{\"type\":\"commonjs\"}' > ./dist/_cjs/package.json && node scripts/rename-cjs.js",
 		"build:esm": "tsc --project ./tsconfig.build.json --module es2015 --outDir ./dist/_esm && printf '{\"type\": \"module\",\"sideEffects\":false}' > ./dist/_esm/package.json",

integrations/viem-v2/scripts/test.js

@@ -0,0 +1,32 @@
+/*
+This script verifies that when Viem is used using Node via the CLI it won't
+prevent Node from exiting cleanly.
+
+See: https://github.com/oasisprotocol/sapphire-paratime/pull/383
+*/
+
+import {
+	createSapphireSerializer,
+	sapphireHttpTransport,
+	sapphireLocalnet,
+} from "@oasisprotocol/sapphire-viem-v2";
+import { createPublicClient, defineChain } from "viem";
+
+const transport = sapphireHttpTransport();
+const chain = sapphireLocalnet;
+const publicClient = createPublicClient({ chain, transport });
+defineChain({
+	id: 0x5afd,
+	name: "Oasis Sapphire Localnet",
+	network: "sapphire-localnet",
+	nativeCurrency: { name: "Sapphire Local Rose", symbol: "TEST", decimals: 18 },
+	rpcUrls: {
+		default: {
+			http: ["http://localhost:8545"],
+		},
+	},
+	serializers: {
+		transaction: await createSapphireSerializer(publicClient),
+	},
+	testnet: true,
+});

integrations/viem-v2/src/index.ts

@@ -119,13 +119,23 @@ export async function createSapphireSerializer<
 		return originalSerializer;
 	}
 
-	// As the serialized is synchronous, fetching keys while running
+	// As the serializer is synchronous, fetching keys while running
 	const fetcher = new KeyFetcher();
 	const provider = client as EthereumProvider;
 	await fetcher.fetch(provider);
-	setTimeout(async () => {
+
+	// The fetcher runs in the background, routinely fetching the keys
+	// This means when the serializer requests a calldata public key one will
+	// have been retrieved pre-emptively.
+	const intervalId: NodeJS.Timeout | number = setInterval(async () => {
 		await fetcher.fetch(provider);
 	}, fetcher.timeoutMilliseconds);
+	// The interval ID is unreferenced to prevent Node from hanging at exit
+	// See discussion on https://github.com/oasisprotocol/sapphire-paratime/pull/379
+	// This is only available in NodeJS, and not in browsers
+	if (typeof intervalId.unref === "function") {
+		intervalId.unref();
+	}
 
 	const wrappedSerializer = ((tx, sig?) => {
 		if (!sig) {