Add dialog to navigate long room topics (#8517)

test/components/views/elements/Linkify-test.tsx

@@ -0,0 +1,64 @@
+/*
+Copyright 2021 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 React, { useState } from "react";
+import { mount } from "enzyme";
+
+import { Linkify } from "../../../../src/components/views/elements/Linkify";
+
+describe("Linkify", () => {
+    it("linkifies the context", () => {
+        const wrapper = mount(<Linkify>
+            https://perdu.com
+        </Linkify>);
+        expect(wrapper.html()).toBe('<div><a href="https://perdu.com">https://perdu.com</a></div>');
+    });
+
+    it("changes the root tag name", () => {
+        const TAG_NAME = "p";
+
+        const wrapper = mount(<Linkify as={TAG_NAME}>
+            Hello world!
+        </Linkify>);
+
+        expect(wrapper.find("p")).toHaveLength(1);
+    });
+
+    it("relinkifies on update", () => {
+        function DummyTest() {
+            const [n, setN] = useState(0);
+            function onClick() {
+                setN(n + 1);
+            }
+
+            // upon clicking the element, change the content, and expect
+            // linkify to update
+            return <div onClick={onClick}>
+                <Linkify>
+                    { n % 2 === 0
+                        ? "https://perdu.com"
+                        : "https://matrix.org" }
+                </Linkify>
+            </div>;
+        }
+
+        const wrapper = mount(<DummyTest />);
+
+        expect(wrapper.html()).toBe('<div><div><a href="https://perdu.com">https://perdu.com</a></div></div>');
+
+        wrapper.find('div').at(0).simulate('click');
+
+        expect(wrapper.html()).toBe('<div><div><a href="https://matrix.org">https://matrix.org</a></div></div>');
+    });
+});