create http utils to use for free port detection and web site pings (#31

)

src/utils/httpUtils.ts

@@ -0,0 +1,89 @@
+import * as http from 'http';
+import * as https from 'https';
+
+import { timeout } from './timer';
+
+/**
+ * Checks local server for a free port.
+ *
+ * @param port Port number to check.
+ *
+ * @returns True if port is free and false otherwise.
+ */
+function isPortFree(port: number) {
+  return new Promise((resolve) => {
+    const server = http.createServer()
+      .listen(port, () => {
+        server.close();
+        resolve(true);
+      })
+      .on('error', () => {
+        resolve(false);
+      });
+  });
+}
+
+
+/**
+ * Tries to find a free port recursively.
+ *
+ * @param port Starting port number
+ *
+ * @returns Available port number or the next port nubmer to try.
+ */
+export async function tryPort(port = 3000): Promise<number> {
+  if (await isPortFree(port)) {
+    return port;
+  }
+  return tryPort(port + 1);
+}
+
+/**
+ * Pings a url to check if it's up.
+ *
+ * @param url The url to ping.
+ * @returns Url ping result promise.
+ */
+export function ping(url: string) {
+  const promise = new Promise<boolean>((resolve) => {
+    const useHttps = url.indexOf('https') === 0;
+    const request = useHttps ? https.request : http.request;
+
+    const pingRequest = request(url, () => {
+      resolve(true);
+      pingRequest.destroy();
+    });
+
+    pingRequest.on('error', () => {
+      resolve(false);
+      pingRequest.destroy();
+    });
+
+    pingRequest.write('');
+    pingRequest.end();
+  });
+
+  return promise;
+}
+
+/**
+ * Waits for a url to be pingable.
+ *
+ * @param url The url to ping.
+ * @param interval The interval to wait between pings.
+ * @param max The maximum amount of time to wait.
+ *
+ * @returns Url ping result promise.
+ */
+export async function waitFor(url: string, interval = 200, max = 30_000) {
+  let time = Math.ceil(max / interval);
+  while (time > 0) {
+    time -= 1;
+    if (await ping(url)) {
+      return true;
+    }
+    await timeout(interval);
+  }
+
+  return false;
+}