Handle waiting list error. (#1165)

UnitTests/Sources/WaitlistScreenViewModelTests.swift

@@ -0,0 +1,40 @@
+//
+// Copyright 2022 New Vector Ltd
+//
+// 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 XCTest
+
+@testable import ElementX
+
+@MainActor
+class WaitlistScreenViewModelTests: XCTestCase {
+    var viewModel: WaitlistScreenViewModelProtocol!
+    var context: WaitlistScreenViewModelType.Context { viewModel.context }
+    
+    override func setUpWithError() throws {
+        viewModel = WaitlistScreenViewModel(homeserver: .mockMatrixDotOrg)
+    }
+
+    func testSuccess() async throws {
+        XCTAssertNil(context.viewState.userSession, "No user session should be set on a new view model.")
+        XCTAssertTrue(context.viewState.isWaiting, "The view should start off in the waiting state.")
+        
+        viewModel.update(userSession: MockUserSession(clientProxy: MockClientProxy(userID: "@alice:matrix.org"),
+                                                      mediaProvider: MockMediaProvider()))
+        
+        XCTAssertNotNil(context.viewState.userSession, "The user session should have been updated.")
+        XCTAssertFalse(context.viewState.isWaiting, "The view should not be in the waiting state after setting a user session.")
+    }
+}