Fix start_sso / start_cas URLs failing to redirect to a authentication prompt (#11681)

* Show screen before login if using start_sso or start_cas

* Add tests

* Fix lint

* Fix lint

* Add one for CAS

* prettier

src/components/structures/MatrixChat.tsx

@@ -393,7 +393,8 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             return;
         }
 
-        if (firstScreen === "login" || firstScreen === "register" || firstScreen === "forgot_password") {
+        // If the first screen is an auth screen, we don't want to wait for login.
+        if (firstScreen !== null && AUTH_SCREENS.includes(firstScreen)) {
             this.showScreenAfterLogin();
         }
     }

test/components/structures/MatrixChat-test.tsx

@@ -41,6 +41,7 @@ import {
     MockClientWithEventEmitter,
     mockPlatformPeg,
     resetJsDomAfterEach,
+    unmockClientPeg,
 } from "../../test-utils";
 import * as leaveRoomUtils from "../../../src/utils/leave-behaviour";
 import * as voiceBroadcastUtils from "../../../src/voice-broadcast/utils/cleanUpBroadcasts";
@@ -51,6 +52,7 @@ import { PosthogAnalytics } from "../../../src/PosthogAnalytics";
 import PlatformPeg from "../../../src/PlatformPeg";
 import EventIndexPeg from "../../../src/indexing/EventIndexPeg";
 import * as Lifecycle from "../../../src/Lifecycle";
+import { SSO_HOMESERVER_URL_KEY, SSO_ID_SERVER_URL_KEY } from "../../../src/BasePlatform";
 
 jest.mock("matrix-js-sdk/src/oidc/authorize", () => ({
     completeAuthorizationCodeGrant: jest.fn(),
@@ -69,6 +71,7 @@ describe("<MatrixChat />", () => {
         setCanResetTimelineCallback: jest.fn(),
         isInitialSyncComplete: jest.fn(),
         getSyncState: jest.fn(),
+        getSsoLoginUrl: jest.fn(),
         getSyncStateData: jest.fn().mockReturnValue(null),
         getThirdpartyProtocols: jest.fn().mockResolvedValue({}),
         getClientWellKnown: jest.fn().mockReturnValue({}),
@@ -1107,6 +1110,64 @@ describe("<MatrixChat />", () => {
         });
     });
 
+    describe("automatic SSO selection", () => {
+        let ssoClient: ReturnType<typeof getMockClientWithEventEmitter>;
+        let hrefSetter: jest.Mock<void, [string]>;
+        beforeEach(() => {
+            ssoClient = getMockClientWithEventEmitter({
+                ...getMockClientMethods(),
+                getHomeserverUrl: jest.fn().mockReturnValue("matrix.example.com"),
+                getIdentityServerUrl: jest.fn().mockReturnValue("ident.example.com"),
+                getSsoLoginUrl: jest.fn().mockReturnValue("http://my-sso-url"),
+            });
+            // this is used to create a temporary client to cleanup after logout
+            jest.spyOn(MatrixJs, "createClient").mockClear().mockReturnValue(ssoClient);
+            mockPlatformPeg();
+            // Ensure we don't have a client peg as we aren't logged in.
+            unmockClientPeg();
+
+            hrefSetter = jest.fn();
+            const originalHref = window.location.href.toString();
+            Object.defineProperty(window, "location", {
+                value: {
+                    get href() {
+                        return originalHref;
+                    },
+                    set href(href) {
+                        hrefSetter(href);
+                    },
+                },
+                writable: true,
+            });
+        });
+
+        it("should automatically setup and redirect to SSO login", async () => {
+            getComponent({
+                initialScreenAfterLogin: {
+                    screen: "start_sso",
+                },
+            });
+            await flushPromises();
+            expect(ssoClient.getSsoLoginUrl).toHaveBeenCalledWith("http://localhost/", "sso", undefined, undefined);
+            expect(window.localStorage.getItem(SSO_HOMESERVER_URL_KEY)).toEqual("matrix.example.com");
+            expect(window.localStorage.getItem(SSO_ID_SERVER_URL_KEY)).toEqual("ident.example.com");
+            expect(hrefSetter).toHaveBeenCalledWith("http://my-sso-url");
+        });
+
+        it("should automatically setup and redirect to CAS login", async () => {
+            getComponent({
+                initialScreenAfterLogin: {
+                    screen: "start_cas",
+                },
+            });
+            await flushPromises();
+            expect(ssoClient.getSsoLoginUrl).toHaveBeenCalledWith("http://localhost/", "cas", undefined, undefined);
+            expect(window.localStorage.getItem(SSO_HOMESERVER_URL_KEY)).toEqual("matrix.example.com");
+            expect(window.localStorage.getItem(SSO_ID_SERVER_URL_KEY)).toEqual("ident.example.com");
+            expect(hrefSetter).toHaveBeenCalledWith("http://my-sso-url");
+        });
+    });
+
     describe("Multi-tab lockout", () => {
         afterEach(() => {
             Lifecycle.setSessionLockNotStolen();