Fix sync init when thread unread notif is not supported (#2739)

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

spec/unit/feature.spec.ts

@@ -0,0 +1,62 @@
+/*
+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 { buildFeatureSupportMap, Feature, ServerSupport } from "../../src/feature";
+
+describe("Feature detection", () => {
+    it("checks the matrix version", async () => {
+        const support = await buildFeatureSupportMap({
+            versions: ["v1.3"],
+            unstable_features: {},
+        });
+
+        expect(support.get(Feature.Thread)).toBe(ServerSupport.Stable);
+        expect(support.get(Feature.ThreadUnreadNotifications)).toBe(ServerSupport.Unsupported);
+    });
+
+    it("checks the matrix msc number", async () => {
+        const support = await buildFeatureSupportMap({
+            versions: ["v1.2"],
+            unstable_features: {
+                "org.matrix.msc3771": true,
+                "org.matrix.msc3773": true,
+            },
+        });
+        expect(support.get(Feature.ThreadUnreadNotifications)).toBe(ServerSupport.Unstable);
+    });
+
+    it("requires two MSCs to pass", async () => {
+        const support = await buildFeatureSupportMap({
+            versions: ["v1.2"],
+            unstable_features: {
+                "org.matrix.msc3771": false,
+                "org.matrix.msc3773": true,
+            },
+        });
+        expect(support.get(Feature.ThreadUnreadNotifications)).toBe(ServerSupport.Unsupported);
+    });
+
+    it("requires two MSCs OR matrix versions to pass", async () => {
+        const support = await buildFeatureSupportMap({
+            versions: ["v1.4"],
+            unstable_features: {
+                "org.matrix.msc3771": false,
+                "org.matrix.msc3773": true,
+            },
+        });
+        expect(support.get(Feature.ThreadUnreadNotifications)).toBe(ServerSupport.Stable);
+    });
+});