Converted tests to typescript. (#6181)

* Converted tests to typescript.

* Run all tests.

* Fixed tests.

* Removed cypress from every installation.

* Use cache for libreoffice.

* Fixed cypress install.

* Fixed cypress install.

src/tests/backend/specs/regression-db.ts

@@ -0,0 +1,30 @@
+'use strict';
+
+const AuthorManager = require('../../../node/db/AuthorManager');
+import {strict as assert} from "assert";
+const common = require('../common');
+const db = require('../../../node/db/DB');
+
+describe(__filename, function () {
+  let setBackup: Function;
+
+  before(async function () {
+    await common.init();
+    setBackup = db.set;
+
+    db.set = async (...args:any) => {
+      // delay db.set
+      await new Promise<void>((resolve) => { setTimeout(() => resolve(), 500); });
+      return await setBackup.call(db, ...args);
+    };
+  });
+
+  after(async function () {
+    db.set = setBackup;
+  });
+
+  it('regression test for missing await in createAuthor (#5000)', async function () {
+    const {authorID} = await AuthorManager.createAuthor(); // Should block until db.set() finishes.
+    assert(await AuthorManager.doesAuthorExist(authorID));
+  });
+});