Add test coverage (#23341)

test/unit-tests/favicon-test.ts

@@ -0,0 +1,61 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import "jest-canvas-mock";
+
+import Favicon from "../../src/favicon";
+
+jest.useFakeTimers();
+
+describe("Favicon", () => {
+    beforeEach(() => {
+        const head = document.createElement("head");
+        window.document.documentElement.prepend(head);
+    });
+
+    it("should create a link element if one doesn't yet exist", () => {
+        const favicon = new Favicon();
+        expect(favicon).toBeTruthy();
+        const link = window.document.querySelector("link");
+        expect(link.rel).toContain("icon");
+    });
+
+    it("should draw a badge if called with a non-zero value", () => {
+        const favicon = new Favicon();
+        favicon.badge(123);
+        jest.runAllTimers();
+        expect(favicon["context"].__getDrawCalls()).toMatchSnapshot();
+    });
+
+    it("should clear a badge if called with a zero value", () => {
+        const favicon = new Favicon();
+        favicon.badge(123);
+        jest.runAllTimers();
+        favicon.badge(0);
+        expect(favicon["context"].__getDrawCalls()).toMatchSnapshot();
+    });
+
+    it("should recreate link element for firefox and opera", () => {
+        window["InstallTrigger"] = {};
+        window["opera"] = {};
+        const favicon = new Favicon();
+        const originalLink = window.document.querySelector("link");
+        favicon.badge(123);
+        jest.runAllTimers();
+        const newLink = window.document.querySelector("link");
+        expect(originalLink).not.toStrictEqual(newLink);
+    });
+});