feat(custom-widgets): Full Mantine v9 + SubFetch support for custom JSX (#6304)

e2e/shared/mock-api-container.ts

@@ -0,0 +1,27 @@
+import { GenericContainer, Wait } from "testcontainers";
+
+import type { StartedTestContainer } from "testcontainers";
+
+export interface MockApiContainer {
+  url: string;
+  stop: () => Promise<void>;
+}
+
+export async function startMockApiContainerAsync(responseBody: unknown): Promise<MockApiContainer> {
+  const body = JSON.stringify(responseBody);
+  const script = [
+    'const { createServer } = require("node:http");',
+    `const body = ${JSON.stringify(body)};`,
+    'createServer((_request, response) => { response.writeHead(200, { "content-type": "application/json" }); response.end(body); }).listen(8080, "0.0.0.0");',
+  ].join("\n");
+  const container: StartedTestContainer = await new GenericContainer("node:24-alpine")
+    .withCommand(["node", "-e", script])
+    .withExposedPorts(8080)
+    .withWaitStrategy(Wait.forHttp("/status", 8080))
+    .start();
+
+  return {
+    url: `http://${container.getIpAddress("bridge")}:8080`,
+    stop: async () => void (await container.stop()),
+  };
+}