Mock HTTP requests in unit tests

src/lib/api.test.ts

@@ -1,20 +1,27 @@
-import { Axios } from 'axios';
+import axios from 'axios';
 import MockAdapter from 'axios-mock-adapter';
 import { HeaptraderAPI } from './api';
 import { expect, jest, test } from '@jest/globals';
 
-let mock: MockAdapter;
-
 class HeaptraderAPITest extends HeaptraderAPI
 {
+    public _mock: MockAdapter;
+
     constructor()
     {
         super("");
-        mock = new MockAdapter(this._axios);
+        this._mock = new MockAdapter(axios);
+        this.setupMockResponses();
+    }
+
+    setupMockResponses(): void
+    {
+        this._mock.onGet("/up").reply(200, {});
     }
 }
 
 test('check uptime', async () => {
-    const api = new HeaptraderAPI();
-    await api.heartbeat();
+    const api = new HeaptraderAPITest();
+    const success = await api.heartbeat();
+    expect(success).toBe(true);
 });