add alerts commponents

src/components/Alerts.js

@@ -0,0 +1,39 @@
+import React, { useEffect, useState, useRef } from 'react';
+import { query, collection, onSnapshot } from 'firebase/firestore';
+
+import './Alerts.css';
+import db from '../firebase';
+
+const Alerts = () => {
+    const [alerts, setAlerts] = useState([]);
+
+    useEffect(() => {
+        if (!allTests) {
+            const q = query(collection(db, "alerts"));
+
+            const unsub = onSnapshot(q, (querySnapshot) => {
+                const testDevices = new Set();
+                const hposTests = [];
+                querySnapshot.forEach((document) => {
+                    const hposTestData = document.data();
+                    hposTests.push(hposTestData);
+                    const { deviceSerialNumber } = hposTestData;
+                    testDevices.add(deviceSerialNumber);
+                });
+                const groups = [...testDevices];
+                // setDevices(groups);
+                setAlerts(hposTests);
+            });
+
+            return () => unsub;
+        }
+    }, []);
+
+    return (
+        <div>
+            {alerts.length}
+        </div>
+    )
+}
+
+export default Alerts;