Improve the experience of testing pull requests (#5942)

extra/kuma-pr/index.mjs

@@ -0,0 +1,26 @@
+#!/usr/bin/env node
+import { spawn } from "child_process";
+import { parsePrName } from "./pr-lib.mjs";
+
+const prName = process.argv[2];
+
+// Pre-check the prName here, so testers don't need to wait until the Docker image is pulled to see the error.
+try {
+    parsePrName(prName);
+} catch (error) {
+    console.error(error.message);
+    process.exit(1);
+}
+
+spawn("docker", [
+    "run",
+    "--rm",
+    "-it",
+    "-p", "3000:3000",
+    "-p", "3001:3001",
+    "--pull", "always",
+    "-e", `UPTIME_KUMA_GH_REPO=${prName}`,
+    "louislam/uptime-kuma:pr-test2"
+], {
+    stdio: "inherit",
+});